Chondrules are a ubiquitous high-T component in primitive meteorites, and as such are key for reconstructing the evolution of dust in the accretion disk surrounding the young Sun. To better constrain the composition of the inner, non-carbonaceous (NC) disk reservoir, and ultimately the source material and growth history of the terrestrial planets, we present here a comprehensive petrographic, chemical, O, Ti, and Cr isotopic, and Al-Mg and Mn-Cr chronometric study of chondrules extracted from ordinary chondrites. We find that chondrules of different textures and chemical compositions (Mg# 67-99) exhibit a narrow range of O, Ti, and Cr isotopic variations. Only one chondrule exhibits ε⁵⁰Ti and ε⁵⁴Cr values that are outside the range of bulk NC materials, likely due to the presence of AOA-like material in its precursor assemblage. Internal Al-Mg isochrons yield an average age of ~1.8±0.6 (2sd) Myr after the start of the Solar System, in line with an age of ~2.2±0.8 Myr obtained from a Mn-Cr bulk chondrule isochron. Overall, the data suggest that the majority of the OC chondrules formed at around 2 Myr after the start of the Solar System in a well-mixed reservoir dominated by NC dust, with only little contribution of anomalous materials from the outer Solar System. This implies that the parent bodies of NC chondrites predominantly accreted dust from their local orbit, and that the barrier separating the inner and outer disk effectively blocked the passage of ~mm-sized dust.

The origin of water on terrestrial planets remains one of the unresolved questions in planetary science. Meteorites have been proposed as a potential source of water to terrestrial planets. Aubrites, one of the differentiated achondrites with their mineralogical similarity to enstatite chondrites, provide crucial constraints on the early stages of planetary accretion and differentiation, particularly concerning the evolution of water. In early 2024, asteroid 2024 BX₁ was recovered shortly after its fall near Ribbeck, Germany, and was subsequently classified as an aubrite based on initial mineralogical and isotopic analyses.

We conducted a detailed investigation of the Ribbeck aubrite through a comparative analysis with other aubrite, focusing on the distribution and characterization of water. We employed infrared spectroscopy to investigate the vibrational properties, bonding environments, and distribution heterogeneities of hydrogen in specimens, complemented by chemical analyses using electron probe microanalysis. The results will show that infrared imaging reveals a heterogeneous distribution of OH vibrations, and broad absorption feature between 3200 and 3800 cm^-1 indicates that water is not structurally incorporated into the primary silicate phases. Instead, hydrogen appears to be hosted predominantly within hydrous phases associated with melt inclusions.

Through this investigation, we deciphered the vibrational mechanisms and origins of hydrous phases in aubrites. Our findings will enhance the understanding of water evolution during the early accretion and differentiation processes of terrestrial planets and provide new insights into the origin of water on Earth.

Airbursts of extraterrestrial projectiles likely occurred frequently throughout the geological past but are rarely available in the geological record to study. Interestingly, natural glasses from Pica in northern Chile (Pica glass) possibly formed during a natural airburst event [1] and could be samples to study such an airburst. The origin of Pica glass, however, is controversial, with pyrometamorphic processes also proposed for their formation [2]. To shed light on the geological origin of Pica glass, we analysed its atomic structure and dynamics using Raman spectroscopy. Raman measurements were performed on thin sections of Pica glass samples, targeting both the glass matrix and crystalline inclusions. The Raman scattering collected from the matrix resembles that of an amorphous SiO₄ network containing significant amounts of broken Si-O-Si linkages, likely caused by alkali and/or alkali earth elements acting as network modifiers. Furthermore, distinct peak pairs at ~383/407 cm^-1 and ~385/406 cm^-1 were identified, corresponding to multilayer and bilayer molybdenum disulfide (MoS₂), respectively. These MoS₂ nanostructures are known from chemical vapour deposition experiments in which volatile MoO₃ reacts with S₂ gas [3]. The MoS₂ structures in Pica glasses are therefore interpreted to have formed by condensation of MoS₂ onto Pica glass melts – resembling deposition in a vapour plume. Preliminary EMP data show correlated, heterogeneous Mo and S concentrations in the glass matrix. Our results support the hypothesis that Pica glass formed by an atmospheric airburst event.

[1] Schultz et al. (2022) Geology, [2] Roperch et al. (2022) EPSL, [3] Pierucci et al. (2016) Sci.Rep.

High-temperature evaporation under high-vacuum conditions has been a critical factor in shaping planetary bodies during their early evolution, as well as in impact events and volcanic degassing on airless worlds such as Jupiter’s moon Io, Earth’s Moon, and Mercury. These processes have a major impact on the distribution and depletion of volatile and moderately volatile elements, yet the exact mechanisms and environmental parameters remain insufficiently understood. Observations from NASA’s MESSENGER mission to Mercury, for example, revealed surface features called hollows—irregularly shaped depressions up to 80 meters deep and several kilometers wide. The bright halos around these hollows and their morphology suggest an ongoing formation process driven by volatile loss. MESSENGER also identified bright regions (faculae) interpreted as pyroclastic deposits, analogous to dark mantle deposits on the Moon, indicating gas-driven volcanic eruptions whose volatile components remain largely unknown. Gaining a better understanding of the volatile species and mechanisms responsible for both hollow formation and explosive volcanism is crucial for constraining Mercury’s volatile history. To investigate these phenomena, we have developed a new laboratory facility designed for in-situ detection of volatiles under high-vacuum conditions at temperatures up to 2000 °C. In this contribution, we introduce the new experimental setup and share preliminary findings.

Planetary bodies exhibit distinct nucleosynthetic isotope signatures that provide insights into the origin of their building blocks [1]. The isotopic composition of Earth and Mars align with nucleosynthetic isotope anomaly trends defined by non-carbonaceous (NC) meteorites, indicating that the terrestrial planets primarily accreted from inner solar system material [2,3]. Furthermore, Earth’s isotopic composition consistently occupies an endmember position within the NC trends. For anomalies in s-process elements this endmember position is absolute, indicating that Earth incorporated a component not represented among known meteorites—an s-process-rich material likely formed in the innermost Solar System and now missing from the meteoritic record.

To investigate the nature of this component, we analyzed fine-grained, matrix-rich fractions from primitive NC chondrites that formed under varying redox conditions and at different heliocentric distances. Our data show that the Ti isotopic composition of these fine fractions deviate from the composition of their bulk host meteorites and are shifted toward—or even beyond—Earth’s isotopic composition. First Zr isotope data from one matrix-enriched fraction indicate that this material is s-process enriched, consistent with an origin in the inner Solar System. This component may represent a missing building block of Earth, heterogeneously distributed within the NC reservoir and selectively preserved in fine-grained material, even if diluted or absent in bulk chondrites.

[1] Dauphas (2017) Nature, 541, 521–524. [2] Burkhardt et al. (2021), Sci. Adv. 7, eabj7601. [3] Mezger et al. (2020), Space. Sci, Rev., 216 :27

The depletion of moderately volatile elements (MVEs) is a key characteristic of planetary materials, but the origins of these depletions are unclear. To investigate the relative importance of nebular vs. planetary volatile depletion processes, we studied the mass-dependent isotopic composition of the MVE Ge in chondrites and iron meteorites. Chondrites exhibit Ge isotope fractionations which correlate with matrix mass fraction and Ge depletion. This indicates mixing between volatile-rich, isotopically heavy matrix and a volatile-poor, isotopically light chondrule component. Despite much larger Ge depletions, iron meteorites exhibit a similar range of Ge isotope fractionations as chondrites. Specifically, the strongly depleted IVA/IVB irons have lighter Ge isotope compositions than CI chondrites, while there rarely are iron groups with heavier compositions. These observations indicate that the MVE depletions among irons cannot simply result from degassing of CI-like starting materials. Instead, these systematics likely reflect two stages of MVE depletion. The first stage took place in the solar nebula and, like for the chondrites, involved mixing of volatile-rich and volatile-poor precursor components. The second stage occurred on the iron parent bodies and likely involved degassing from molten iron cores, after collisional disruption of the parent bodies. While for most irons the Ge elemental depletion mostly occurred during this second stage, these losses do not appear to have induced large Ge isotope fractionations. As such, an iron parent bodies' Ge isotopic composition largely reflects that of its precursor material. Thus, both primordial nebular and secondary planetary volatile loss shaped the MVE budgets of differentiated planetesimals.

One of the goals of the Oman Drilling Project has been to advance our understanding of the processes that formed and modified the oceanic crust in the Wadi Tayin massif of the Oman ophiolite. In a reconnaissance study of samples from the CM-1A drill core we show that both the lower layered gabbros with dunite-troctolite and dunite-wehrlite layers and the 150 m thick dunite units of the crust-mantle transition zone (CMTZ) mostly display suprachondritic initial γOs up to +54 (γOs represents the deviation of ¹⁸⁷Os/¹⁸⁸Os from a mean chondritic value) at the time of their formation around 97-95 Ma. In contrast, underlying mantle harzburgites and dunites at the drill site display mantle-like γOs (95 Ma) of -8 to +2, implying that most magmas that crystallized the lower layered gabbros and the CMTZ dunites never equilibrated with the local mantle rocks underneath. Other data on gabbros further up in the lower crust of the Wadi Tayin massif also indicate positive γOs (95 Ma), however, because of the high Re/Os of some samples, it is difficult to calculate reliable initial γOs (95 Ma)-values (Peucker-Ehrenbrink et al. 2012, Geology 40, 199-202). Nevertheless, from the limited data it appears that most of the lower oceanic crust in the Wadi Tayin massif may have been affected by magma or fluid with suprachondritic γOs (95 Ma). We will discuss hypotheses concerning the origin of the radiogenic osmium in the lower crust and propose ways of testing these ideas.

During the Pleistocene epoch the Alpine scenery with its surroundings was repeatedly reshaped by glacial activity. Subglacial erosion led to basin-shaped structures, so-called ‘overdeepenings’ (OD), embedded in bedrock. Their sedimentary fillings are important archives for understanding glacial history and the glacial impact on environmental transformation. Some of these infills are composed of multiple cycles representing separate glaciations.

Numerous well investigated cores in the Northern Alpine Foreland led to the recognition of typical fining-upward OD-fill sequences – characterized by glaciolacustrine deposits overlying glacially originated diamicts at the basal unconformity. These fining-upward sequences typically start with glacitectonites that regularly transition into coarse-grained, sand-dominated, and finally fine-grained basin fills, and can occur as several unconformably stacked units.

In the ICDP-DOVE framework, two new cored profiles were recovered north of Lake Constance (drill sites Gaisbeuren and Lichtenegg). These consist of OD-fills that are not typical for the Alpine Foreland, because they are almost entirely composed of diamictic deposits. While these deposits show some variations in concentration and size of clasts, well sorted lacustrine sediments are missing. Potential reasons for the atypical character of these OD-fills are to be discussed.

The contact zones of two Miocene subvolcanic phonolite intrusions towards underlying sedimentary country rock within the Kaiserstuhl Volcanic Complex, SW Germany, are exposed in drill cores. The phonolites form fine- to medium grained and homogeneous intrusive bodies. The dominant primary minerals are foids, sanidine, aegirine-augite, wollastonite; common accessories are andradite, fluorapatite, titanite and götzenite. Postmagmatic alteration transformed all foids to zeolites (Spürgin et al. 2019). The country rock consists of finely laminated, dark claystones with variable carbonate content and intercalated, thin sulphate beds. It belongs to the Oligocene Wittelsheim Formation, which was deposited in shallow lakes during the subsidence of the Upper Rhine Graben. At the contact to phonolite, brittle and ductile deformation structures developed on the cm- to dm-scale during emplacement. Furthermore, centimeter-wide magmatic veins were injected close to the contact, and crosscutting veins containing zeolites, calcite and fluorite penetrate phonolite and claystone.

Phonolites become obviously porphyric close to the country rock. Several major and trace elements show depletion in proximity to the contact (e.g., Na₂O, Al₂O₃, SiO₂, Zr, Ba), whereas others are enriched compared to the general phonolite chemistry (e.g., CO₂, MgO, Sr). Transition zones extend several meters from the contact into the phonolites.

Wall rock interaction, manifested by mineralogy and texture, is capable to alter the chemical composition of phonolitic magmas. However, exchange processes during magma emplacement work only in a zone of a few meters, which is thin compared to the intrusion sizes of several hundred meters.

Spürgin, S., Weisenberger, T.B. & Marković, M., 2019, American Mineralogist 104, 659-670.

The Paraná-Etendeka large igneous province (PELIP) covers ca. 1.5 million km² in South America and Africa. Its voluminous continental basalt flows are related to the opening of the South Atlantic Ocean in the Early Cretaceous (~135-132 Ma). In South America, the geochemical and petrological evolution of the PELIP has been extensively studied in Brazil, where the largest exposures are found, while the Uruguayan portion remains less studied. We conducted a multidisciplinary study on the Uruguayan lavas, which host the world-class amethyst-agate deposits of Los Catalanes. Our study integrates field observations, petrography (including cathodoluminescence microscopy), whole-rock geochemistry, isotopic compositions, and mineral chemistry, to provide new insights into the magmatic evolution of the PELIP in Uruguay, and its role in conditioning the system for secondary silica mineralisation. Unaltered lava levels show loss on ignition (LOI) <2 wt.%, and support our petrogenetic interpretation. The lavas are low-Ti tholeiites and range in composition from basaltic andesite to andesite. They are enriched in incompatible elements relative to MORBs and present “arc-like” trace element patterns, such as Large-Ion Lithophile Elements enrichment relative to High-Field Strength Elements, and negative Nb anomalies. The trace element patterns and Sr, Nd, and Pb isotope signatures suggest an enriched mantle source subsequently modified by magma-crust interaction. On the other hand, amethyst-hosting levels within individual flows show higher LOI (up to 9 wt.%) and lower Ca, Mg and Al concentrations, suggesting low-temperature hydrothermal alteration and/or weathering. The association between mineralised geodes and altered lavas demonstrates that the silica mineralisation was controlled by pervasive fluid infiltration.

The Indus Suture Zone (ISZ) in north western Himalayas is major tectonic suture dividing the Indian plate from Kohistan Island Arc (KIA) and Eurasian plates. It coincides with the subduction zone where the Tethys oceanic lithosphere subducted beneath KIA and Eurasia causing the obduction of several bodies of Tethyan upper mantle along ISZ, two prominent among them are Jijal Complex and Sapat Complex. Mantle peridotites of these complexes individually lie at a distance of ~ 80 Km and consist of harzburgites, pyroxenites, dunites and serpentinites.

In order to understand the effects of subduction and fluid rock interaction we measured the boron isotopic signatures of Jijal and Sapat mantle rocks through LA-ICPMS at FIERCE. Whole rock δ¹¹B was analyzed on nano-powder pressed pellets and mineral δ¹¹B of olivine and pyroxene were obtained in-situ on polished thin sections. The whole rock δ¹¹B of Jijal ultramafics ranges from -4.32 to 6.43 ‰ with average δ¹¹B of 0.36 ‰. On the contrary, the Sapat ultramafics show higher average δ¹¹B of 2.80 ‰ and range of -0.13 ‰ to 7.66 ‰. The results from both mantle sections are significantly higher than the depleted mantle δ¹¹B value of -7.1 ‰. The difference between boron isotopic signature of Jijal and Sapat complex suggests forearc position of the later and potentially different magma compositions. The overall higher values of both mantle bodies indicate towards a more enriched mantle component or the influence of slab derived fluids from subducted serpentinites.

Over the past 32 million years, slab rollback and trench retreat in the Aegean region have led to back-arc extension and southward migration of the subduction zone. Consequently, several age-progressive plutonic centres with associated volcanism formed over a ~300 km distance. This study compiles new and existing geochemical data from igneous rocks of the four oldest magmatic centres in northern Greece: Leptokaria/Kassiteres (~32 Ma), Maronia (~29 Ma), Samothraki (~23–16 Ma), and Limnos (~22–19 Ma).

Major and trace element data reveal significant compositional diversity among the magmatic units. Maronia, Samothraki, and Limnos exhibit shoshonitic compositions characterized by strong enrichment in incompatible elements, whereas Leptokaria/Kassiteres is dominated by a high-K calc-alkaline series with more moderate incompatible element enrichment.

Isotopic data indicate that the two oldest centres, Leptokaria/Kassiteres and Maronia, have less radiogenic Sr and more radiogenic Nd signatures than the younger shoshonites from Samothraki and Limnos. In addition, the shoshonitic rocks display higher La/Yb ratios than the calc-alkaline samples, with the highest values observed in the Limnos and Samothraki samples.

High P/Nd and Ba/La ratios in the shoshonites are consistent with a lower degree of partial melting, however, suggest an additional influence from a mantle source enriched by subducted P- and Ba-rich sediments. Nd/Sr and Hf/Nd ratios, together with isotopic signatures, indicate that sediment–mantle mixing played a major role before partial melting. The observed geochemical and isotopic diversity along the arc is likely the result of mixing of variable sediment with the mantle, possibly in the form of a heterogeneous peridotite–sediment mélange.

The 55 km-thick Kohistan-Ladakh Arc (Northern Pakistan) was an intra-oceanic arc for 120 Ma prior to becoming an Andean-type continental arc from 50 to 40 Ma. We present new geochemical data from the Kohistan-Ladakh Arc and use existing geochemical and geochronological literature data from this arc to constrain the growth and chemical evolution of the arc crust. The ultramafic to mafic lower crust of the Kohistan-Ladakh Arc is older than their intermediate to felsic middle to upper crust. Olivine, clinopyroxene, anorthite and amphibole fractionated from basaltic magmas to form the intermediate to felsic plutons of the Kohistan Batholith. The middle to upper crust of the Kohistan-Ladakh Arc has higher Th/La and lower ¹⁴³Nd/¹⁴⁴Nd ratios than the older lower crust. The later intermediate to felsic plutons of this arc formed by fractional crystallisation of basaltic magmas and were more influenced by slab sediment melts than crustal contamination. The 150 Ma Matum Das Pluton and Hunza Formation were cogenetic. The 67-65 Ma plutonic rocks of the eastern Kohistan Batholith are genetically related to the 65-60 Ma Teru Formation and Dir Group. The high (Dy/Yb)_N ratios of some of the mafic plutonic rocks imply deeper melting of the Kohistan-Ladakh sub-arc mantle once the arc had attained a thickness of >42 km Late Cretaceous. The older volcanic and plutonic rocks in the Kohistan-Ladakh Arc resemble those of the active Izu-Bonin-Mariana and Tonga intra-oceanic arcs, whereas the younger igneous rocks are more similar to those in the active Cascade continental arc.

Diamonds crystallize from fluids or melts circulating in the Earth's mantle. Direct analysis of these fluids is possible when they remain entrapped during diamond growth, a rare feature in gem-quality stones. We present a three-step approach to analyse thin silicic fluid films (≤5 μm; cf. Nimis et al., 2016) surrounding mineral inclusions in gem-quality diamonds using slow LA-ICPMS depth profiling.

1. Non-destructive characterization: FTIR and Raman spectroscopy are used to classify diamonds and identify mineral and fluid inclusions. Confocal micro-Raman mapping reveals a heterogeneous 3D distribution of fluid films containing Si₂O(OH)₆ and Si(OH)₄ around mineral inclusions.
2. Laser ablation time estimation: LA drilling experiments on a diamond fragment helped to determine the ablation rate. Combined with the inclusion depth, this allows estimation of the time needed to reach a mineral inclusion at a constant LA repetition rate.
3. Targeted LA-ICPMS depth profiling: A photo of the marked diamond, showing both the diamond surface and the inclusion in focus, is overlaid on the live image, enabling accurate targeting of the mineral inclusion during LA-ICPMS analysis. Slow ablation (~2 Hz) resolves distinct chemical signals. Fluid-mobile (e.g., Ba, Sr) and mineral-specific elements (e.g., Mg, Fe for olivine) are used to differentiate between fluid, host diamond, and mineral inclusion in a single depth profile.

Despite limitations from pit tailing, graphitization, depth-dependent ablation rates, and biased inclusion depth estimates (diamond’s high refractive index), we successfully analysed two samples. These results allow comparison of entrapped fluids with previously studied High-Density-Fluids (HDFs) from fibrous diamonds using trace element ratios.

Mafic rocks are dominant rocks in Shakha Rash Mountain, Shakha Rash occurs in the middle of Bulfat complex, which represents a part of in Zagros suture zone (ZSZ), northeastern Iraq. Gabbro, olivine gabbro, pyroxene hornblende gabbro and alkali gabbro are the main rock types of mafic rocks cropping out in the area. These rocks even its different variety rock types, its showing different granularity from fine to coarse texture. These mafic rocks are calc-alkaline affinity high aluminum basalt. Compared with the primordial mantle, they are enriched in Large Ion Lithophile Elements (LILE) and Light Rare Earth Elements (LREE) over High Field Strength Elements (HFSE) and Heavy Rare Earth Elements (HREE) close to oceanic arc basalt (OAB). Their enrichment in the LREE relative to HREE is relatively low fractionation (La_N/Yb_N) (1.64-3.31, ave. ~2.39) chondrite), with Eu anomalies changed from weakness negative to positive. This feature together with relative depletion of Nb, Pr, Nd, Zr, Hf and Ti but Cs, Ba, K, U and LREE enrichment. From trace element indicate that these rocks associated with volcanic arc basalt (VAB), this volcanic arc formed as a result of enclosed of Neo-Tethys. Trace and rare earth elements show that these rocks crystallized from magma melted from spinel lherzolite, by patch partial melting.

The Dinarides fold-and-thrust belt formed during the Cenozoic collision between the Adriatic microplate and Eurasia. In the External Dinarides, thick carbonate platform deposits dominate, and structures generally strike NW–SE with SW-directed thrust vergence due to Eo-Oligocene shortening. In the Gorski Kotar region (NW Croatia), structures shift to a N–S trend with localized east-directed thrusting. Field data and geological profiles suggest that before Cenozoic contraction, the area experienced E–W-directed extension during the Lower Jurassic, leading to a ~2.7 km thick syn-rift sequence, about ten times thicker than coeval strata in adjacent regions.

To investigate thickness variations and structural architecture, we developed three geological cross-sections based on field measurements and geological maps. These were used in 2D kinematic forward models to simulate deformation over time. Raman Spectroscopy of Carbonaceous Material (RSCM) was applied to the highest structural unit to assess thermal maturity.

RSCM results show that Permian strata overlying Jurassic and Triassic units were heated to 227 ± 15 °C, implying ~7 km exhumation, assuming a geothermal gradient of 30 °C/km. The cross-sections reveal a NE- to E-directed passive roof thrust developed above a complex triangular structure. This present-day architecture is largely inherited from Lower Jurassic extension, accommodated by WSW-dipping normal faults. Lower Jurassic extension across the Adriatic shelf contributed to basin development in the Eastern Alps, Southern Alps, Apennines, and Dinarides, representing an early phase of intracontinental rifting prior to the opening of the Piemont-Liguria Ocean. These results emphasize the long-lasting influence of inherited structures on Cenozoic deformation.

The Motagua Fault in Guatemala is the southern one of two sinistral strike-slip faults that make up the North American-Caribbean plate boundary system. Both faults are known to produce large earthquakes, the most recent one being a magnitude 7.5 on the Motagua Fault that caused severe damages to the infrastructure of the country and about 23,000 deaths. Together both faults accommodate ca. 20 mm of slip per year. At present, the Motagua Fault is more active than the Polochic Fault to the north, taking up most of the slip, while in the past the contrary was the case. However individual slip rate estimates thus far are very vague and mainly based on GPS measurements. At the Río El Tambor site southwest of Cabañas, multiple river terraces are laterally offset by the Motagua Fault. We used optically stimulated luminescence and radiocarbon dating on these terraces to provide the first field-based estimate for the slip rate of the Motagua Fault. Additionally, we used satellite imagery, drone lidar surveys, and historical data to map and systematically evaluate offsets on geomorphic markers. These indicate that the total offset on the Motagua Fault is at maximum ca. 20 km and thus, the switch of the high slip rate from the Polochic to the Motagua Fault probably did not happen earlier than in the Pleistocene.

Kinematic analysis of small-scale shear faults is ubiquitously applied to infer principal strain directions in brittlely deformed terrains. Often, the directions vary greatly with position. In such cases, non-uniform principal strain directions are frequently interpreted as evidence for successive deformation phases. In the Cape Archangelos area, the pervasive coverage of multi-scale brittle faults lends itself to testing the validity of this practice. Here, kilometer-scale oblique normal faults form first-order faults regarding higher-order, meter- to decameter-scale shear faults. All faults affect Plio-Pleistocene marine strata and thus adhere to neo-tectonic deformation. This allows us to test to what extent principal strain axis orientations, inferred from the inversion of 365 higher-order shear faults, are influenced by their proximity to some 80 first-order normal faults at 14 stations. First-order normal faults form two sets, one striking NNE, the other NNW. As it is unlikely that the overall deformation regime changed during Plio-Pleistocene to Recent times, both sets formed under the same deformation regime. Based on the inversion of higher-order shear faults, principal strain axes indicate either overall N-S or E-W horizontal extension. Fault populations at each station are kinematically homogeneous. This is consistent with faulting during a single deformation regime. Moreover, half of the stations indicating approximately E-W extension are located on or close to first-order normal faults, whereas the other stations showing chiefly N-S extension are located up to hundreds of meters away from these faults. We conclude that the presence of first-order structural discontinuities can significantly influence principal strain axis directions.

Mid-Ocean Ridges (MORs) and transform faults are a significant feature of the Earth’s surface that develop due to accretion of new material in an extensional regime. On a much smaller scale, stylolites are a dissolution feature in rocks that develop during compression and form distinct teeth structures. We present a comparison between the two features and argue that transform faults in MOR are similar to the sides of stylolite teeth with both features representing kinematic faults (KFs). First, we present a numerical model of stylolite and MOR growth and show that in both cases KFs nucleate and grow spontaneously. Secondly, we use Family-Vicsek scaling technique of describing fractal self-affine interfaces, which have been used for stylolites, to characterize the pattern of MOR systems. Our results show that both systems have self-affine scaling characteristics with similar scaling regimes. Both show a larger roughness exponent at small scales, a smaller exponent at the intermediate scale followed by a flattening of the system at the largest scale. For stylolites the physical forces behind the scaling are the surface energy (small scale), the elastic energy (intermediate scale) followed by the system reaching the correlation length where growth stops. For MORs the physical forces behind the scaling are not yet clear. However, the self-affine scaling shows that transform faults at MORs do have a fractal spacing, rather than a preferred spacing. Our study offers a new perspective on natural roughening phenomena on various scales and a new view on the development of MORs.

The Upper Rhine Graben (URG) represents a tectonically-complex section of the European Cenozoic rift system that crosses the European continent from N to S. However, the basin history remains unclear due to the heterogeneous development of subsidence rates together with phases of uplift and intricate changes of the local stress field.

This study represents an approach to unravel the basin evolution by retro-deforming a 3D geological dataset derived from interpretation of a 3-D seismic survey. The model covers an approximately 10 km x 30 km wide area between Darmstadt and Worms, in the northern part of the URG. The data were acquired for hydrocarbon exploration purposes and comprise 12 faults (mostly striking N-S and dipping with 55°E) and 9 seismic horizons, the latter range from the Base Iffezheim Formation (5 Ma) down to the Top of the crystalline basement. By backstripping and decompacting each horizon along complex fault patterns, we

1. Examine the effect of retro-deformation on fault plane geometry based on Allan maps,
2. Quantify subsidence rates across the study area derived from thickness changes
3. Understand the tectonic history and fault activity through analysis of the 3D retro-deformation.

Additionally, we attempt to estimate the potential reactivation of major faults using slip- and dilation tendency analysis. The results give first insights to the basin development of the northern Upper Rhine Graben, on which future studies can be built.

The Serbo-Macedonian Massif consists of high-grade orthogneisses with lenses of amphibolites, eclogites, and paragneisses derived from Gondwana-affiliated protoliths. In the Ograzhden Unit, amphibolite-facies paragneisses represent a diverging sedimentary succession based on their detrital ages (Peytcheva et al., 2015, Geol. Balcanica 44, 51-84). Near the village of Lebnitsa, a metasediment succession occurs that is different from these paragneisses in composition and local preservation of cross-bedding. The metasediment comprises quartzite and mica-Al₂SiO₅-garnet-rich layers. These observations suggest a mature fluvial sediment protolith.

We analysed zircons to characterize the detrital age component and origin of the Lebnitsa metasediment. The zircon population indicates various age clusters, with major peaks at 530 Ma and 450 Ma. The Struma Diorite and Frolosh Formations could have been the source for the former peak (516-579 Ma, Zagorchev et al., 2011, Bulg. Geol. Soc. “Geosciences 2011”), whereas the 450 Ma cluster is representative of the post-Cadomian orthometamorphic basement (440-480 Ma) of the Ograzhden Unit (Peytcheva et al., 2015, Geol. Balcanica 44, 51-84). Unlike most of the Ograzhden paragneisses, no peaks younger than 425 Ma are present. The metamorphic assemblage and Quartz-in-Garnet Raman elastic barometry of the Lebnitsa metasediment suggest amphibolite-facies metamorphism. The tectonic foliation and lineation correspond to the ones observed in the surrounding basement, suggesting common tectonic history.

Based on the newly obtained data, we propose that the Lebnitsa metasediment represents a monocyclic cover deposited on the Ograzhden basement in post-Cadomian times and metamorphosed at the amphibolite facies conditions during the Alpine orogeny together with the surrounding basement.

The subduction of aseismic oceanic ridges at convergent plate margins causes a reduction in submarine margin relief, which alters the balance of topographic and tectonic stresses. The stress changes increase the compression of the upper plate and may hence be relevant for understanding surface uplift and mountain building in response to ridge subduction. However, the detailed effects of relief changes and other parameters affecting the upper-plate force balance at subduction zones remain to be explored. Here we use analytical and two-dimensional finite-element models to investigate the effects of relief changes and additional parameters that may change during ridge subduction, including the initial trench depth, the slab dip angle, the slab curvature, and the submarine surface slope angle.

Our modeling results show that the compression caused by a decrease in submarine margin relief depends not only on the total relief change but also on the initial trench depth before ridge subduction and the geometry of the subducting slab. In addition, changes in the submarine surface slope angle during ridge subduction alter the compression of the upper-plate and may affect the total amount of surface uplift. Additional finite-element models with a setup of adjusted to the subduction of the Cocos Ridge (Central America) indicate that surface uplift in response to a reduction in submarine margin relief explains up to 50 % of the high topography in Costa Rica.

Understanding the coupled multi-scale geodynamic processes related to the subduction of the oceanic Nazca Plate beneath the South American Plate is one pre-requisite to better assess seismic hazards in the region. It is essential to identify all relevant forces within the system, such as negative buoyancy of the subducting slab or mechanical coupling between the Andean domain and the Pampean foreland, to analyze tectonic processes like subduction or strain transfer and localization. We approach this by initially investigating the present-day physical state of the subsurface, including first-order variations in pressure caused by mean lithostatic stress, temperature, and rock composition as constrained by multi-disciplinary observations.

For this we build data-based 3D lithospheric models to characterize the system’s response to these forces, with particular attention to the rheological behavior dictated by rock composition, temperature, and pressure. By employing an integrated methodology combining seismic velocity conversions with gravity modelling (IGMAS+), we create refined 3D models of the crust and lithosphere that capture structural, thermal, and rheological properties of the subsurface, as these exert significant control on spatial variations in lithospheric strength and deformation behavior.

Datasets such as surface heat flow, earthquake catalogues, as well as geodetic observations can then be used to validate the models and shed light onto the underlying geophysical processes active in the region.

The south flank of Kilauea volcano (Hawaii, USA) is actively moving seaward at rates of up to ~10 cm/year along a basal décollement. This movement is accompanied by earthquakes and landslides. The Hilina Slump is located on top of the mobile flank and has not yet failed catastrophically as seen elsewhere on the Hawaiian Islands. It is thought that stacked thrust sheets at the toe of the submarine flank act as a buttress, helping to stabilize the active slump. The mechanical properties of the slump and thrust sheets are poorly understood but may significantly influence their deformation behavior and the overall stability of Kilauea’s flank. To better understand these systems, we conducted direct shear experiments on samples collected from submarine exposures of both the thrust sheets and the Hilina Slump. Our results reveal both velocity-weakening and velocity-strengthening frictional behavior, depending on sliding velocity. Velocity-strengthening occurs predominantly at low velocities. Intact samples are stronger and tend to exhibit more velocity-strengthening behavior, whereas powdered samples, representative of pre-existing fault zones, are weaker and show more velocity-weakening behavior. This suggests that fault zones could experience unstable sliding. Additionally, altered surface sediments from the Hilina Slump show stick-slip behavior. Overall, the variable material behavior across the submarine flank may explain the range of deformation structures and slip styles observed at Kilauea.

Crust underlying the Island of Rhodes is part of the forearc of the eastern Hellenic subduction zone. Deformation of the forearc rocks appears to be influenced by oblique plate convergence, subduction roll-back and horizontal-axis rotation, the relative importance of these processes is not well known. The southeast coast of Rhodes hosts Pliocene to Pleistocene marine strata, attributed to fault-controlled basin formation. However, it is poorly understood how faulting is intertwined with deposition of marine strata and how basin formation relates to the first-order tectonic processes. To examine these relationships in detail, the Lardos area was selected, due to its excellent exposure of marine sedimentary strata and fault scarps. Neotectonic deformation on multiple scales was assessed employing satellite- and drone-based imagery, differential GPS as well as lithological and structural mapping. Collectively, these observations point to the following sequence of tectono-sedimentary stages of basin formation: Normal faulting initiated the Pre-Pleistocene graben formation. Based on the occurrence of the sedimentary breccia along the fault scarps and displaced Pleistocene marine terraces, graben-bounding normal faults continued to be active during and after the Pleistocene. Faulting affected Pre-Pleistocene carbonate rocks and the unconformably overlying Pleistocene marine sedimentary strata. During uplift of the southeast coast of Rhodes, marine terraces formed and reshaped the paleo relief. Graben formation can be attributed to overall ENE-WSW, i.e., plate boundary-parallel, extension of the forearc rocks. This extension direction can be explained by increasing crustal stretching along the forearc as a consequence of progressive tightening of the curved Hellenic subduction zone.

The semichatovae Transgression marks an episode of major eustatic sea level rise in the Upper Devonian. It is commonly described by the wide spread of the index conodont Palmatolepis semichatovae and has been proposed to define the boundary between the middle and upper Frasnian substages within Frasnian conodont zone 11. The index species is known from the Moroccan Meseta (Mrirt region) but so far absent from the cratonic northern Gondwana shelf (Anti-Atlas). There, the eustatic event has been roughly recognized based on lithological and geochemical changes, which indicate a drastic turnover of low-oxygen water masses. We attempt to provide conclusive evidence for the event and associated environmental changes in a transect from the Meseta to the eastern Anti-Atlas by applying multiple methods, such as geochemical proxies for detrital input and hypoxia, stable carbon isotopes, microfacies developments, and changes of conodont assemblages. Outcrops were chosen to represent different facies types, from pelagic carbonate platform to more argillaceous intrashelf basins. The goal is to provide additional information on both the timing and duration of the event, as well as the environmental impact it had on the Gondwana margin. New detailed bio- and chemostratigraphic data shall assist the ongoing search for formal substage definition and stratotype selection.

Ediacaran glacial deposits have been described in recent years from several peri-Gondwana units, including the Weesenstein Group of the Elbtalschiefergebirge (Elbe Zone, Saxo-Thuringia) (e.g. Linnemann et al. 2018, Int. J. Earth Sci., 107, 885-911). These sedimentary rocks with only low-grade metamorphic overprint have been considered the oldest rocks of the region. The Weesenstein Group comprises two formations, following Linnemann et al. (2018): the older (but see below) Seidewitz Formation overlain with gradual transition by the Müglitz Formation. The former comprises quartzite and quartz schist horizons and a thick quartzite unit, named the Purpurberg Quartzite, interpreted to be a glacio-eustatic controlled low-stand deposit. The Müglitz Formation comprises mainly greywacke, partly pebble bearing, of the Weesenstein diamictite; the latter has been interpreted to belong to the Ediacaran glaciomarine diamictites of Cadomia. The stratigraphic concept, however, has recently been put into question based on the findings of a low-diversity trace fossil assemblage in the Purpurberg Quartzite, indicating a Palaeozoic, most likely Early Ordovician age, and evidence for an inverted stratigraphic order of the two formations (Meinhold et al., 2025, Geol. Mag., 162, e10). Palaeoenvironmental models of glacio-eustatic controlled deposition of the Purpurberg Quartzite of the Seidewitz Formation due to sea-level fall during an Ediacaran glaciation need to be abandoned. Both the age (Ediacaran or Palaeozoic?) of the Müglitz Formation and the nature of its contact with the Seidewitz Formation, are in need of further study. The term Weesenstein Group requires a revision, adjusting for the new stratigraphic concept of the area.

As part of the Geothermal Master Plan of North Rhine-Westphalia, the Geological Survey of NRW carried out a nearly 1000 Meters deep drilling in the city centre of Krefeld. Since detailed geological data of the deeper subsurface was sparse in the area, cores were recovered for the entire Palaeozoic interval of the drilling. The primary objective was to fully penetrate the Mississippian (Carboniferous) sedimentary succession of the Kohlenkalk Group and to characterize the geothermal potential of this reservoir.

The borehole intersected a complex sedimentary succession. Particular focus is placed on the lithological and facies variability of the carbonate platform facies of the Kohlenkalk Group, which comprises alternating layers of mostly limestone and dolomite. We present first results based on core descriptions, geophysical well logging, and biostratigraphic analyses which allow a refined stratigraphic subdivision of the sedimentary succession. In addition, the overlying Tertiary and Quaternary deposits provide important insights into the more recent geological development of the Lower Rhine Embayment.

The data obtained from the well contribute essential geoscientific information for the better understanding of the geological setting, for the advancement of regional 3D geological models and for assessing the geothermal potential of deeper subsurface formations. The borehole thus represents a key stratigraphic reference point for future geological modelling, resource assessment, and site planning in support of the energy transition in North Rhine-Westphalia.

Optical petrography and X-ray Diffraction (XRD) are essential techniques for analysing the mineralogical and textural characteristics of heavy minerals in sedimentary formations. This study applies optical petrography and XRD to the Tamale and Oti Groups within the Voltaian Supergroup of Ghana to enhance understanding of their provenance, diagenetic history, and economic potential. Optical petrography enables detailed characterization of mineral grains, identifying key features such as zoning, inclusions, and alteration patterns under transmitted light. XRD complements this by determining crystalline phases and quantifying mineral compositions, especially in fine-grained sediments where traditional microscopic methods face limitations.

Preliminary results indicate a diverse heavy mineral assemblage, including zircon, tourmaline, rutile, garnet, phosphates, glauconite, micas, apatite, spinel and monazite, suggesting contributions from both igneous and metamorphic source terrains. Petrographic analysis reveals minimal grain morphological variations for stable minerals like zircons and post-depositional modifications, including dissolution features. XRD further confirms the presence of stable heavy minerals, reinforcing their potential as provenance indicators. These findings contribute to broader sedimentary petrology and geochemical studies, offering insights into the depositional environment and tectonic evolution of the Voltaian Basin.

By integrating optical petrography and XRD, this study advances interdisciplinary approaches in geoscience, supporting sustainable resource exploration and development in Ghana. The results have implications for mineral exploration, environmental assessments, and basin evolution models, reinforcing the significance of advanced analytical techniques in sedimentary research.

The COSC-2 drilling project recovered ~2276 m of continuous core through the thin-skinned thrust system of the Caledonian Orogen in Sweden. We present a detrital zircon geochronological study of its Palaeozoic sedimentary section, which comprises a continuous Lower Cambrian(?) through Lower Ordovician(?) autochtonous to parautochtonous succession, marked by variable detritus sources along the profile.

The >350 m-thick Lower Cambrian portion was initially sourced locally from the Transcandinavian Igneous Belt, with a gradual shift toward a Sveconorwegian provenance. The upper part of the autochthonous sequence, just below the Alum Shale Formation, is marked by a flux of late Neoproterozoic-Cambrian grains. The maximum depositional age of the uppermost Lower Cambrian strata is estimated at 530.5 ± 4 million years. Despite tectonic overprint in its shaly middle part, the Alum Shale Formation remains continuous, encompassing a complete Middle Cambrian to Lower Ordovician sequence. Above, in the parautochthonous succession, detritus again reflects Sveconorwegian sources, resembling the provenance of Ordovician greywackes in the Lower Allochthon.

Comparison of detrital zircon spectra from the Lower to Middle Cambrian strata across Baltica shows a consistent influx of late Neoproterozoic-Cambrian detritus. Statistical analyses indicate that in Central Scandinavia, the likely source of this zircon population is the southern Santacrucian Arc. This flux reflects arc magmatism tied to subduction of the Mirovoi Ocean beneath Baltica.

Acknowledgements: We thank the COSC scientific drilling teams led by Henning Lorenz. The National Science Centre, Poland funded this research (projects 2018/29/B/ST10/02315 and 2019/33/B/ST10/01728) and the Deutsche Forschungsgemeinschaft supported the COSC-2 studies by OL (Le 867/13-2).

The Bellingshausen Sea sector is largely covered by the West Antarctic Ice Sheet, which impedes direct geological investigations. The rift-related structures of the West Antarctic Rift System presumably control the course of ice streams. In turn, the glacially eroded troughs provide pathways for warm oceanic deep water, which causes basal melting of the overlying ice.

During Polarstern cruise PS134 we collected rock samples from onshore nunataks and clastic sediments from glacial outlets. We apply petrographic analyses and radiometric dating on apatite and zircon to characterize the source area hidden beneath the ice and to investigate the thermotectonic evolution of the Bellingshausen sector.

Our data will provide insights into the geological units present under the ice as well as information on the timing of activity, mode, and kinematic relationships of the rift branches of the West Antarctic Rift System in the Bellingshausen Sea sector. These new data allow to refine palaeotopographic models of West Antarctica, which will provide boundary conditions for understanding and modelling the onset of the glaciation of West Antarctica. Combined with offshore seismic and sedimentological information, the new data will also allow to visualize onshore and offshore denudation and burial over time, which will contribute to understanding source-sink relationships, drainage patterns and the regional long-term landscape evolution.

Rutile provides a wealth of petrochronological information in metamorphic geology and due to its high stability during processes of the sedimentary cycle, rutile takes a special position in sedimentary provenance analysis. Besides being one of the classical minerals datable using the U−Pb system, rutile incorporates a broad range of trace elements, many of those being incompatible in most of the common metamorphic minerals. Although a large number of multivariate statistical tools including machine-learning approaches is available, current rutile discrimination schemes suffer from focusing on uni- and bivariate approaches, leading to large compositional overlaps. Here we compiled a dataset of 2,335 rutile trace-element analyses (1,605 new analyses and 730 from Lueder et al. (2024))) from 110 metamorphic rock samples of 48 localities covering a wide range of pressure−temperature conditions. After showing that the subsampling and testing strategy of the classical random forest algorithm (Breiman, 2001) is inappropriate for such hierarchical data structures, we introduce a modified version (hierarchical random forest) which provides realistic and generalized error estimates, improving hyperparameter tuning and performance. By applying this concept, we present a novel and multivariate rutile discrimination scheme, using the concentrations of 16 elements. The model correctly predicts the source rock composition (felsic versus mafic) in ~89 % of the cases and the metamorphic gradient (≤350 °C/GPa versus >350 °C/GPa) in ~84 %. Combined with U−Pb dating, this enables to gain time-resolved insights into the geodynamic evolution of the hinterland, taking rutile provenance analysis to the next level.

The Isua supracrustal belt (ISB) represents a key example of Archean crustal development and is renowned for containing some of Earth's oldest supracrustal rock sequences. However, the precise conditions and timing of its metamorphic history remain subjects of ongoing debate. Crucially, this understanding forms the foundation for competing hypotheses regarding Eoarchean vs. Neoarchean tectono-metamorphic evolution.

This study investigates felsic (Qz + Pl) veins associated with Grt-Bt-Pl-Qz schists located near a large tonalite-trondhjemite-granodiorite (TTG) body with an intrusion age estimated at 3.7 Ga. These felsic veins may represent either in-situ melts of the host rock or TTG-derived melts and subsequent interaction with surrounding rock.

Special focus is placed on observed mineral textures within the host rock, the felsic veins, and their interfaces. Garnet porphyroblasts in the host rock exhibit rounded grains and complex zoning pattern, particularly in grossular and spessartine components, along with various mineral inclusions. In contrast, garnet grains in the veins are larger, irregular and more homogeneous in composition and host polyphase melt inclusions, suggesting distinct growth mechanisms between the host rock and the veins.

Zircon and monazite grains in felsic veins, garnet porphyroblasts and in the host rock will be dated and rare earth element (REE) patterns will be analyzed to distinguish detrital and crystallization ages to constrain the timing and nature of melting and/or melt-rock interaction events and to compare these data with the known history of the ISB. This integrated approach will clarify the formation of felsic veins and contribute to models of Archean crustal evolution.

The Isua supracrustal belt (ISB) is one of the earth’s oldest preserved rock sequences and provides crucial insights into early Archean evolution. Polyphase metamorphism and variable degree of metasomatism have significantly obscured primary signatures requiring an understanding of metasomatic processes to reconstruct the evolution of the ISB.

A local metasomatic reaction zone in the western 3.8 Ga felsic-metavolcanic zone has been sampled, covering a traverse with decreasing alteration from the centre to the rim to identify the protolith, quantify element fluxes and reconstruct metamorphic conditions. Progression of the metasomatic front is characterised by four mineral assemblages: (1) talc-chlorite, (2) talc-chlorite-quartz, (3) chlorite-cordierite-biotite-quartz±kyanite, (4) cordierite-biotite-quartz±kyanite. While high Mg#: > 90 in ferromagnesian minerals appear to be constant across the outcrop, a systematic decrease in whole rock magnesium and nickel accompanied by an increase in silica, potassium, sodium, calcium and phosphorus can be observed. We interpret the element fluxes to be the consequence of infiltration by a fluid previously equilibrated with ultramafic rocks. Thermodynamic calculations indicate P-T conditions of 600-650°C and 0.5-0.7 GPa. The protolith has been constrained as dacitic to rhyolitic. In addition, the comparison of the least altered sample with a calculated average composition of the 3.8 felsic-metavolcanic rocks lead to the conclusion that they originate from the same protolith and had the same whole-rock chemistry before metasomatism. Further research is needed to constrain the origin of the fluid and the temporal relationship between metasomatism and metamorphism.

Eleven new U-Pb LA-ICP-MS zircon ages of the Moodies Group of the Barberton Greenstone Belt from tuffs, felsic lava flows, and aquatically reworked tuffaceous siltstones confirm that this up to 3.7 km thick siliciclastic unit in dominantly coastal-plain and tidal facies was deposited within only a few million years while being deformed into tight, steeply plunging folds. LA-ICP-MS dating of the Moodies Group gradually reaches its limits because (1) analytical uncertainty approaches the time scale of the research questions, and (2) xenocrystic and reworked zircons in the tuffs are commonly hydrothermally altered and subjected to multiple metamorphic events, resulting in complex populations. A diachronous onset of Moodies deposition is not discernible. The onset (ca. 3224±3 Ma) is statistically indistinguishable from the end (ca. 3217±8 Ma) of Moodies deposition. Deformation began at ca. 3221±3 Ma and had ended prior to ca. 3210±10 Ma. The large granodioritic Lomati River Intrusive laccolith is likely of Moodies ages (ca. 3220±8 Ma) and was folded while still viscoplastic. Its syndepositional character at only ca. 1 km depth below the surface is consistent with a dike stockwork, extensive hydrothermal alteration, and the eruption of the basaltic Moodies Lava. Hydrothermal silicification of Moodies sandstones in its halo preserved a large microbial lagerstätte. Moodies stratigraphy thus appears to be dominated by rapid subsidence, balanced by high depositional rates and accompanied by significant mafic to felsic magmatism. Sediment in the central BGB was mainly sourced from the erosion of intermediate to felsic volcanics in the rising Onverwacht Anticline.

Banded Iron Formations (BIFs) are Precambrian marine chemical sediments that can be used as prime geochemical archives to reconstruct Earth's early ocean chemistry. The ~3.4-billion-year-old BIF in the Daitari Greenstone Belt, India, is one of the oldest so far known BIF that has only experienced greenschist-facies metamorphism [1] and provides a great opportunity to reconstruct Paleoarchean marine environments.

This study presents new major and trace element data, along with Nd and Hf isotopic compositions from BIF of individual Fe- and Si-rich layers. Exceptionally low concentrations of immobile elements indicate that the BIF are remarkably pure chemical precipitates without significant detrital contamination. Most samples exhibit shale-normalized rare earth element and yttrium (REY_SN) patterns characteristic of Archean seawater, including positive La_SN, Eu_SN, and Gd_SN anomalies, super-chondritic Y/Ho ratios, an absence of negative Ce_SN anomalies, and enrichment of heavy REY_SN over light REY_SN. These features point to an anoxic, open-ocean depositional setting influenced by high-temperature submarine hydrothermal activity. Most BIF samples plot on ¹⁷⁶Lu–¹⁷⁶Hf and ¹⁴⁷Sm–¹⁴³Nd reference lines between 3.3 and 3.5 Ga, consistent with geological evidence [1]. Initial εNd values range from +1.7 at 3.5 Ga to +3.0 at 3.3 Ga and suggest that mantle-derived sources influenced ancient Daitari seawater. Extremely radiogenic εHf values (from +33.9 to +11.4) reflect either isotopic disturbance or incongruent weathering of emerged continental crust similar to what is observed from the Neoarchean onwards [2].

[1] Hofmann et al., 2022, Earth Sci. Rev. 228.

[2] Viehmann et al., 2014, Geology 42.

The evolution of hyper-arid surface environments on Earth and Mars is strongly linked to the occurrence of three calcium sulfates minerals: gypsum (CaSO₄∙2H₂O), bassanite (CaSO₄∙0.5H₂O), and anhydrite (CaSO₄) [1,2]. While the formation mechanism of the first, gypsum, is well understood, though do the crystallisation pathway and the required (paleo-)environmental conditions for the formation of the water-free sulfate, anhydrite, still depict a conundrum.

To date, there exists no model that can reliably predict how anhydrite forms at earth’s surface conditions. While thermodynamics favour its occurrence, it is hardly achieved on laboratory time scales at conditions fitting either the Atacama Desert on Earth or the surface of Mars.

Considering recent transmission electron microscopy findings [3] advocating for a complex, non-classical nucleation mechanism for all calcium sulfates, we present analyses of natural samples from different facies of the Atacama Desert, i.e. aeolian deposits, (sub-)surface nodules and selenites, to identify key features that promote the nucleation and growth of anhydrite under planetary surface conditions.

Additionally, alternative pathways for anhydrite nucleation facilitated by metabolic products of biological organisms (e.g. fungi, lichen, cyanobacteria) found in soils of the Atacama [4] will be discussed.

References:

[1] Voigt et al. (2020) Glob Planet Change 148:103077

[2] Vaniman et al. (2018) Am Min 103(7):1011–1020

[3] Stawski et al. (2016) J Phys Chem C 124(15):8411-8422

[4] Knief et al. (2020) Glob Planet Change 148:103077

The sedimentary rocks of the lower Pretoria Group record the first appearance of oxygen in Earth’s atmosphere and surface environments during the ca. 2.32 Ga Great Oxidation Event (GOE). While the change of ocean water redox-conditions during the GOE has been extensively investigated, the link between fluctuations in continental weathering patterns and their impact on the marine realm during this critical time interval in Earth’s history is less known. The black shales of the 2.32–2.25 Ga Timeball Hill Formation (TBH), deposited directly after the onset of atmospheric oxidation during the GOE, denoted by the disappearance of mass-independent fractionation of S-isotopes in the underlying Rooihoogte Formation, bear the potential to provide a better understanding of these processes.

Here, we report newly obtained major and trace element data of the EBA-1 drill core, covering the Rooihoogte, the Timeball Hill (including the Rietfonteindam Diamictite) and the Boshoek formations, at very high-spatial resolution, providing detailed insights into the continental weathering conditions and associated changes in the marine environment. While the Rooihoogte and lower TBH formations display intense weathering on the continents under warm climates, the weathering intensity massively decreased through the upper TBH, suggesting strong atmospheric cooling, terminating in the deposition of the Rietfonteindam Diamictite, which corresponds to a major glaciation. The overlying Boshoek Formation records a renewed increase in weathering intensity due to climatic warming. These fluctuations in weathering conditions were accompanied by changes in nutrient fluxes, which in turn influenced the oceanic redox conditions on a basin-wide if not global scale.

Extremophiles thrive in hostile environments on Earth, such as hydrothermal vents on the ocean floor. These organisms developed a number of adaptations that allow them to survive in conditions of extreme temperature, up to 122 °C, and pressure, up to 125 MPa. A critical factor in their survival is the stability of adenosine triphosphate (ATP), an essential energy carrier whose hydrolysis could limit metabolic processes under extreme conditions. This remarkable adaptability of extremophiles has led to a growing interest in studying them, particularly with regard to exploring the potential for extraterrestrial life in our solar system.

In situ Raman spectroscopy, combined with a hydrothermal diamond anvil cell (HDAC) and a gas-pressurized autoclave, was used to study the hydrolysis of ATP in aqueous solutions at temperatures of 80 °C, 100 °C, and 120 °C and pressures up to 1670 MPa. The results indicated that ATP undergoes rapid hydrolysis at elevated temperatures, with rate constants of 4.34 × 10^-3 s^-1 at pH 3 and 2.91 × 10^-3 s^-1 at pH 7 at 120 °C, corresponding to half-lives of only a few minutes. An effect of pressure on ATP hydrolysis was observed, with hydrolysis rates increasing almost tenfold as pressure increased from 365 MPa to 1670 MPa at 100 °C. The influence of Na⁺, Ca²⁺ and Mg²⁺ was investigated. It was found that while Na⁺ and Ca²⁺ have a negligible effect, Mg²⁺ significantly reduces the hydrolysis rate up to 30% at 80 °C and 50% at 120 °C, thereby kinetically stabilizing ATP under extreme conditions.

The Eoarchean Isua supracrustal belt (ISB) in southern West Greenland contains one of Earth's oldest rock records. Its tectono-metamorphic evolution remains debated, particularly regarding timing and peak conditions in mafic to ultramafic lithologies. Phase equilibria modelling suggested homogeneous peak metamorphic conditions (550-600 °C; 0.8-1.0 GPa), though recent studies of a dunite lens suggested ultra-high pressure (UHP) to prograde low-pressure deserpentinization.

This study examines metamorphism in ultramafic rocks from lens B in the northwestern ISB, analyzing four samples from rim to center using EPMA, SEM, EBSD, ICP-MS and thermodynamic modelling.

The lens rim shows strong foliation with antigorite (X_Mg=0.91) + magnesite + magnetite ± ilmenite. The center shows decreased deformation with antigorite (X_Mg=0.98) + fosterite (X_Mg=0.97) + magnesite + magnetite ± Ti-chondrodite/Ti-clinohumite.

We found Ti-clinohumite being replaced by Ti-chondrodite, indicating cooling at lower pressures. The presence of carbonate without brucite or talc emphasizes CO₂'s role in phase relations. Thermodynamic modelling shows antigorite stability is CO₂-dependent, limiting antigorite + magnesite stability to pressures < 1 GPa at XCO₂ > 0.005. EBSD analysis shows olivine deformation preceded antigorite growth, supported by magnetite, magnesite and Ti-humite phases associated with olivine breakdown.

This study suggests the lens exhibits a fluid-mediated reaction front achievable at homogeneous amphibolite-facies conditions, rather than requiring UHP conditions or deserpentinization.

We are exploring the origin of some of Earth’s oldest monazites discovered in the Isua supracrustal belt (ISB). Monazite, crucial for light rare earth elements Th and U, is widespread in low Ca granites and metapelites. Its formation depends on the Al/Ca ratio of the host rock and ceases below a critical threshold and is potentially preceded by allanite at lower metamorphic grades.

Modern geological settings often feature rocks with high Al/Ca ratios suitable for monazite formation. In contrast, Archean rocks, typically basaltic to ultramafic, generally have low Al/Ca ratios, prohibiting monazite growth. However, during crustal differentiation, some rocks exceeded this threshold, enabling initial monazite formation, though specifics remain uncertain. Our study presents evidence of early monazite formation in the ISB.

Focusing on a "metapelitic" rock with garnet porphyroblasts, hosting two generations of monazite, we find older monazites in garnet cores dating to ~3.6 Ga, placing them among the oldest monazites known to date, while younger ones in garnet rims and matrix date to ~2.7 Ga.

The absence of other monazite occurrences in Isua and the in situ formation of both generations suggest a metamorphic origin rather than detrital. These rocks, with a pelitic bulk composition, represent some of the oldest preserved clastic sedimentary rocks, sourced from ultramafic, mafic, and felsic igneous rocks or reflecting metasomatic alterations of basaltic rocks.

The presence of ~3.6 Ga monazite establishes a minimum age for the high Al/Ca composition essential for monazite growth in Isua's Archean crust, supporting interpretations of late Eoarchean metamorphism.

Banded iron formations (BIFs) are authigenic marine sedimentary rocks that may record the chemical composition of ancient seawater and are widely used as geochemical archives to reconstruct Precambrian marine environments. In this regard, the approximately 3.25 Ga old BIFs of the Fig Tree Group, Barberton Greenstone Belt, have been shown to be prime recorders for Palaeoarchaean marine environmental conditions and seawater chemistry during the early stage of Kaapvaal Craton formation [1, 2].

To further evaluate the suitability of this BIF and its individual mineral phases as geochemical archives, we present trace and major element concentrations of 13 layers dominated by magnetite, chert, and siderite from the BARB 4 drill core. Immobile element (Zr, Th) concentrations vary over four orders of magnitude between the samples. In combination with non-seawater-like shale-normalised (subscript SN) rare earth element and yttrium (REY) patterns, this indicates variable degrees of detrital contamination. However, cherts and two of the magnetite samples show typical Archaean seawater-like signatures with positive La_SN Gd_SN, and Y_SN anomalies as well as a depletion of light REY relative to heavy REY_SN, indicating a seawater-derived origin. The lack of a negative Ce_SN anomaly and positive Eu_SN anomalies indicate anoxic environmental conditions and contributions of high-temperature hydrothermal fluids, respectively.

Our results show that chert in BIF is the most reliable mineral phase for obtaining information to reconstruct BIF depositional environments through deep time.

[1] Hofmann, 2005, Precambrian Res. 143, 23-49.

[2] Satkoski et al., 2015, EPSL 430, 43-53

Integrating geomorphology, sedimentology, sedimentary petrology, and provenance analysis has significantly advanced our understanding of sedimentary processes. Depositional dynamics—particularly sediment partitioning, landscape evolution, and signal propagation—are now closely linked to tectonic and climatic forcing within the Sediment Routing System (SRS) framework. Quantitative provenance analysis (QPA) contributes a compositional dimension that enhances sediment budget estimates and enables the quantification of anthropogenic impacts. Nevertheless, a fully integrated, multidisciplinary approach remains underdeveloped.

This study addresses these gaps through three objectives: refining Sediment Generation Models (SGM) by coupling lithology, relief, and climate; developing a streamlined QPA–SRS workflow for sand and silt apportionment; and assessing the resolution of sedimentary signal reconstruction at historic (10² yr), intermediate (10²–10⁶ yr), and deep-time (≥10⁷ yr) scales.

At historic timescales, compositional and morphotectonic analyses capture the impact of human activity on sediment generation, while QPA integrated with OSL and sedimentological data successfully traces drainage responses to Holocene climatic variability. In deep-time systems, the combination of high-resolution provenance techniques and detailed sedimentology underscores a key limitation: the need for precise, coeval dating of climatic, tectonic, and depositional events.

While identifying natural controls in modern settings is relatively straightforward, transient landscapes often obscure the geological record. Focusing on sfirst-cycle SRS, this study develops an integrated framework with SGM providing essential baseline data. Systematic application of these models across diverse lithological, tectonic, and climatic settings will promote greater unification of sedimentary geology sub-disciplines, offering more accurate reconstructions of ancient systems and refined predictions of future landscape and climate evolution.

High-altitude lakes are sensitive archives of environmental change, yet remain understudied with respect to sediment deposition dynamics. In particular, the tropical Andes of Ecuador are globally-relevant biodiversity hotspots and carbon sinks, which are highly threatened by climate change and human impacts. To learn from the past, we study the depositional history of Lake Caricocha, a high-elevation caldera lake (> 3,700 m asl) located in the Mojanda Lake region, north of Quito, Ecuador. A 72 cm-long sediment core was recovered and analyzed using a multi-proxy approach, including visual core description of the lake sediment facies, X-ray fluorescence core scanning, magnetic susceptibility, C/N and grain-size analysis. Radiocarbon dating was combined with tephra analyses to provide viable sediment accumulation rates over the last three millennia. Granulometric and geochemical data were evaluated using multivariate statistical techniques, including cluster analysis, principal component analysis, and end-member modelling analysis, to infer sediment provenance and deposition dynamics within the lake-catchment system.

The record reveals three major stratigraphic units intercalated with at least eight tephra layers and a high-energy event layer. Our analysis separates detrital sediment input from sediment input by volcanic eruptions, post-eruption reworking or catchment erosion during extreme events that activate the few existing inflows. We discuss grain-size and geochemical data as key to understand and unmix the lake-internal deposition from terrestrial erosion dynamics. This study contributes to a growing understanding of sediment dynamics in tropical high-altitude lakes, and their potential implications for local water resource management.

High-mountain regions are highly sensitive to climate change, but there is limited understanding on how landscapes will respond to climate and land-use change, e.g., land abandonment due to rural-urban migration. In our study, we explore the potential of using lake sediments of Lago della Maddalena to serve as a high-resolution archive of Late Holocene paleoenvironmental changes. The study site is located at ~1974 m a.s.l. in the northern Maritime Alps (Italy), a climatically sensitive transition zone between Mediterranean and continental influences. The lake provides a valuable sedimentary record for identifying naturally and anthropogenically induced environmental dynamics in grazing-induced treeline settings. We aim to identify distinct sedimentary environments, material sources, and underlying patterns.

A multi-proxy approach was applied to two short sediment cores using visual lithofacies descriptions, C/N, macrocharcoal analysis, and micro-XRF core scanning. Principal component and cluster analyses of centered log-ratio transformed XRF data revealed four distinct geochemical units, indicating shifts in sediment provenance and depositional processes. The sediment composition suggests alternating phases of increased clastic input and carbonate-rich conditions. C/N ratio points to a predominance of terrestrial organic matter. Low charcoal content suggests that fire plays a minor role in the catchment area.

We discuss challenges of disentangling proxy data from broader paleoenvironmental signals, especially in contexts where climate, land-use, and geological processes interact. This work provides a methodological basis for future studies seeking to better resolve the timing and drivers of ongoing environmental change in the southwestern Alps.

Abu Galum Reserve is located in the northeastern part of South Sinai near the Gulf of Aqaba. It has a total area of about 500 km2 and is made up of granite mountains that end abruptly on a narrow coastal plain. The area also includes canyons, flood fans, coastal lagoons, and marshes. The study area suffers from the dangers and problems caused by torrential rains, which affect human activities, as the study area is characterized by drought and lack of water, but the sudden and heavy rainfall causes torrential torrents that leave sabotage and destruction. This paper aims to assess the risk of flash floods by using the engineering hydrological model (HEC-HMS), to calculate the torrent hydrograph curve and estimate the amount of torrential flow and its flow rates, thus calculating the depth of rain for different return periods up to 100 years.

Keywords: Abu Galum, engineering hydrological modeling, HEC-HMS.

The late basanitic pyroclasts of the 1951 eruption at Fogo Island (Cape Verdes) contain ultramafic cumulate xenoliths and euhedral kaersutite megacrysts up to 12 cm in size. The megacrysts are characterized by abundant cavities that locally contain vesicular basaltic glass with small clinopyroxene phenocrysts. Some of these cavities are crystallographically oriented and remind of hopper textures. Micro-CT analyses reveal that the cavities are only in part interconnected and locally form funnel-like openings to the crystal surface. The kaersutite megacrysts also contain numerous pyrrhotite rods aligned perpendicular to the crystal surface, some pyrrhotite blebs, and locally stellate spinel aggregates. We interpret these structures to reflect rapid growth of the megacrysts in a volatile-rich silicate melt under the presence of a CO₂-H₂O-dominated fluid phase and abundant droplets of exsolved sulfide melt. Glass compositions within the cavities suggest that this melt was slightly more primitive than the erupted host melt. Barometric data based on clinopyroxene-melt equilibria within cavity glass, as well as kaersutite composition, indicate that megacrysts grew at pressures of 630–700 MPa, overlapping with a range of 620–640 MPa obtained for coevally erupted cumulate xenoliths, which is within the uppermost mantle. Possible cause for the rapid growth at such depths could be sudden liquidus increase due to H₂O loss of the host melt, following magma mixing or CO₂ flushing. We suggest that this occurred within a crystal mush where mobility of coexisting fluid and sulfide phase was limited.

The in-situ analysis of stable isotope ratios, e.g. ⁷Li/⁶Li, ⁵⁶Fe/⁵⁴Fe, in natural and experimental samples has become an indispensable tool for investigating inter-mineral, intra-mineral, and mineral–melt isotope fractionation processes, such as diffusion, equilibrium isotope exchange, or crystal growth / dissolution. A pre-requisite for reliable high-precision measurements of those isotope ratios, however, is the availability of suitable solid reference materials that serve as bracketing standards during the in-situ analyses. Here, we have investigated a series of mm-sized natural amphibole and biotite crystals using both, solution-based MC-ICP-MS and fs-LA-MC-ICP-MS, in order to assess their suitability to serve as reference materials for in-situ δ⁵⁶Fe measurements. These crystals have previously been employed to establish Fe²⁺/ΣFe analyses by electron microprobe using the flank method [1]. The amphibole candidates are classified as hastingsite (Amp-11), pargasite (Amp-12, Amp-40), or tremolite (Amp-15), showing FeO_T contents between 4.2 and 12.7 wt%. The four biotite candidates (Bt-18, Bt-25, Bt-26, Bt-41) display FeO_T concentrations between 8.2 and 28.6 wt% [1]. The results of our in-situ δ⁵⁶Fe analyses by fs-LA-MC-ICP-MS indicate that the investigated biotite crystals are sufficiently homogeneous, and the in-situ data are in good agreement with the Fe isotopic compositions obtained by solution-based MC-ICP-MS within analytical uncertainty. Regarding the amphibole crystals, the in-situ and solution-based Fe isotope measurements reveal that only Amp-11 and Amp-40 represent promising candidates for serving as reference materials. In contrast to this, Amp-15 shows significant internal inhomogeneity and Amp-12 displays large crystal-to-crystal variations in δ⁵⁶Fe.

References:

[1] Li et al. (2019): Chem. Geol., 509, 152-162.

The application of phase-field modeling to geological systems enables a quantitative investigation of how various boundary conditions influence texture evolution. This may be used to reconstruct the timescales of non-equilibrium solidification in magmatic rocks (e.g. through the use of crystal size distributions, CSD, and diffusion chronometry). In this study, we developed a multi-component solidification model tailored for magmatic systems accommodating an unlimited number of crystals with varying orientations and anisotropies. Thermodynamic data from the MELTS database in combination with a surface anisotropy model (using surface energies from the literature) were used to model the growth of multi-faceted crystals.. Experiments as well as numerical models to study the coarsening of olivine crystals in a melt were carried out at a high constant undercooling (ΔT = 250 K at 1247 °C for annealing times of 1h, 4 h,18 h, and 72 h). Average growth rates and interface mobility in the experiments and models were consistent with each other for a coarsening behavior governed by equations of diffusion-controlled growth: d ≈ Mt^1/3, where d is an average diameter of crystals and M is a kinetic coefficient. From the kinetic coefficient an average diffusion coefficient of components can be evaluated as D ≈ 2 x 10^-10 m²/s. This value is similar to diffusivities expected for divalent cations in many basaltic melts, and somewhat faster than the diffusion rates expected for network formers such as Si.

Amphibole represents an important rock forming mineral commonly occurring in calc-alkaline and alkaline igneous rock and its complex crystal structure allows the incorporation of a wide variety of major and trace elements. However, despite the crucial role of amphibole in magmatic systems, the effects of various parameters on amphibole crystallisation systematics are still poorly constrained. In particular, data on the influence of halogens on amphibole stability and composition are scarce although the replacement of (OH) by halogens (e.g. Cl and F) on the W site is commonly observed in natural amphiboles. Thus, in this study, we investigate the systematic influence of halogens on amphibole stability under magmatic conditions.

For this purpose, we ran high-pressure and high-temperature phase equilibria experiments in internal heated pressure vessels (IHPV). As starting material, we used a synthetic powder mixture, based on a natural basalt from the Adamello Batholith in Northern Italy, systematically spiked with Cl and F contents ranging from 0.5 to 1.5 wt.%. The experiments were performed under H₂O-rich fluid-present conditions at 200 MPa with temperatures ranging from 1000 to 950 °C and fO₂ buffered at NNO+2.3.

Our data reveal that halogens affect the crystallisation systematic of amphibole, where the presence of Cl and F show distinctively different effects on phase equilibria (i.e. stabilisation of amphibole by F and destabilisation in the case of Cl). Consequently, currently existing tools to predict the stability and crystallisation conditions of amphibole in magmatic systems (e.g. geothermobarometers) need to be used cautiously when dealing with halogen-bearing magmas.

To date, reconstructing temperature and pressure conditions in magmatic systems remains challenging. Commonly used tools, such as thermobarometers, often suffer from imprecise underlying calibration datasets and erroneous application to natural samples resulting in significant uncertainties on obtained results. This study uses phase equilibria experiments on a primitive arc tholeiitic basalt from the Mutnovsky volcano in Kamchatka to evaluate the performance of different clinopyroxene-based thermobarometers in calc-alkaline and tholeiitic arc systems. Common application errors were evaluated using an improved analytical protocol for EPMA measurements (e.g. improving statistical errors by accounting for the number of individual measurement points which are averaged for P-T calculations, selecting matrix-matching calibration and reference standards, and investigating the occurrence of beam damage). Errors introduced during data processing were accounted for via clinopyroxene component calculations and measurements of H₂O contents of coexisting silicate glasses. Our results demonstrate that the performance of commonly-used clinopyroxene-based thermobarometers can substantially be improved by thoroughly addressing analytical and application-related uncertainties.

Subsequently, we applied our refined analytical approach to natural samples from Mutnovsky volcano. Calculated temperatures of clinopyroxene crystallization during pre-eruptive magma storage range from 1310 °C to 1440 °C and pressures from 0 to 500 MPa. Pressure estimates are in alignment with previous studies postulating a shallow magma chamber at ~1.5-3 km depth (≈ 40-80 MPa), although showing a distinctively higher variability. In contrast, temperatures are overestimated by the clinopyroxene-based thermobarometers as previous studies report onset of clinopyroxene crystallization around 1000 °C indicating a potential systematical error of the applied thermobarometers.

Investigations of core material from a borehole that was drilled in the Elbe Zone south of Dresden suggest the existence of a unique volcanic structure. It is situated in a complex geological area with units of different ages, e.g. Neoproterozoic greywackes of the Weesenstein Group, metamorphosed Palaeozoic sediments and igneous rocks of the Elbtalschiefergebirge and sediments of the North Bohemian Cretaceous Basin.

The borehole gives insight into a 50 m thick succession of a volcanic breccia underneath a few metres of Quaternary fluvial gravel. The colour varies between greenish-grey at the uppermost part to greenish-black down to the final depth of 55.3 m. Clast analyses allow to classify the rock as bomb-bearing lapillistone. Besides pyroclasts of different modal composition and texture, xenoliths occur representing ultramafic mantle xenoliths and diverse crustal fragments. Notable are amphibole megacrysts up to 10 cm in size.

Among the juvenile components, it can be distinguished between dominating scoria lapilli and subordinate crystallized melt fragments, which contain olivine, clinopyroxene, sometimes plagioclase in a glassy, partly altered groundmass (mesostasis). The mafic clasts are accompanied by xenoliths of greywacke, gneiss, granite and claystone with foraminifera of supposed Upper Cretaceous age. Such mixture suggests a Strombolian eruption of an alkaline basalt magma, accompanied by phreatomagmatic pulses. The mineralogical variation of the juvenile components hints to different magma batches in a complex feeding systems for this monogenetic volcano. A Tertiary age can be assumed which is common for the Lusatian Volcanic Field further east.

The eruptive products of the Pulvermaar in the West Eifel volcanic field contain nodules, which are rounded pieces of plutonic rocks coated by lava rims. The plutonic parts may represent disrupted fragments of a magma mush zone, and thus provide insights into magma mush processes at depth. Their bulk compositions are similar to those of the magmatic coating, indicating that the plutonic parts may have been formed by the slow cooling of previous magma pulses at depth. The plutonic parts are composed of coarse grained olivine, clinopyroxene, biotite and amphibole, which crystallised in this relative order. The modal abundance of minerals varies widely, ranging from pyroxenites containing only clinopyroxene and olivine to hornblendites composed mainly of amphibole and biotite. The lava coating cross-cuts all mineral phases and records the final stage of magma emplacement prior to eruption. The chilled magma consists of glass, bubbles and phenocrysts of olivine and clinoproxene, showing some overlap with the olivine and clinoproxene compositions in the plutonic part. Growth zoning, recording different stages of evolution, is present in olivine, clinopyroxene and amphibole. The compositions of the zones in olivine (Fo_core = 0.88, X_Ca = 0.004 and Fo_rim = 0.84, X_Ca = 0.02) and clinopyroxene (Wo_49-52En_32-43Fs_16-08 in different zones) represent growth in different magmatic environments. Preliminary modelling using MELTS is able to reproduce the observed crystallization sequence, but the pressure-temperature conditions of crystallization remain poorly constrained and require detailed experimental and thermobarometric studies, which are currently underway.

Understanding when and how magmatic systems evolve toward eruption is key to forecasting and hazard mitigation. This study applies diffusion chronometry to two basaltic rift eruptions - the 2021 Fagradalsfjall eruption in SW Iceland [1] and the 1950 Mauna Loa SWRZ eruption in Hawai‘i [2] - to constrain the timing of magma mobilization, mush disaggregation, and eruption run-up.

At Fagradalsfjall - the first deep-sourced eruption on a mid-ocean ridge segment monitored with modern instrumentation - diffusion chronometry in olivine and plagioclase identifies three pre-eruptive phases: (1) a priming phase with long diffusion timescales indicating deep magmatic upheaval years before eruption, largely undetected geophysically; (2) a transition phase beginning ~1 year prior, coinciding with regional seismic and geodetic unrest; and (3) a run-up phase marked by steep gradients in both diffusion ages and seismicity, reflecting rapid magma ascent.

At Mauna Loa, diffusion chronometry of six olivine types reveals a shorter, yet similarly structured timeline: (1) a ~1.5-year priming phase, recorded by high-Fo olivine, intensifying in the final 8 months and preceding detectable seismicity by ~2 months; (2) a transition phase 6–4 months prior, marked by increased magma flux, mush disruption and seismic onset; and (3) a run-up phase starting ~2.5 months prior, involving more evolved olivines and culminating in a magnitude 6.4 earthquake days before eruption.
These case studies underscore the diagnostic value of diffusion chronometry in tracking the onset, escalation, and pace of pre-eruptive processes in basaltic systems.

[1] Kahl et al. (2023a) Geology 51, 184-188.

[2] Kahl et al. (2023b) Bulletin of Volcanology 85:75.

The density of metamorphic reactions occurring in subduction zones, due to intense fluid-melt activity, is very high. One of the minerals resulting from all these reactions, both in the downgoing slab and in the serpentinized mantle wedge, is magnetite. Its study is crucial to understanding geodynamic processes, as it gives information about oxidized fluids, temperature, trace elements mobility, etc... It encompasses not only metamorphic petrology but also tectonic processes of accretion, exhumation/obduction, as well as ore geology, as it is a ubiquitous mineral in numerous ore deposit types. Being able to date magnetite, providing a temporal framework to all these reactions, is to put in one more piece of this big puzzle.

Advances in the LA-ICPMS have made that currently, the U-Pb dating reaches far beyond the traditionally dated minerals (zircon, monazite, rutile, etc.). In this context, at the FIERCE laboratory of the Goethe University-Frankfurt, we have investigated the possibility of dating magnetite. Magnetite from several localities has been studied, resulting in a variety of U and Pb contents (up to a few µg/g for U) as well as a significant spread on the U/Pb ratios. This has allowed us to date the studied samples, with internal precisions as good as 1.5% in the best of the studied cases.

Recognising the possibility of dating such a mineral is only the first step in the implementation of the technique. Currently, we are comparing the ages obtained by different methods and different minerals, to search for a magnetite reference material.

Kaolinite is a finely divided phyllosilicate which is widespread at the Earths’ surface. It is formed by intense weathering of aluminous silicates such as feldspars or micas and is extremely stable at Earth’s surface temperature conditions. Electron paramagnetic resonance (EPR) spectroscopy dating of kaolinite is a promising geochronological method for this clay mineral which cannot be dated by conventional radiometric [1]. Combined to (U-Th)/He dating of iron oxides and oxyhydroxides, it thereby enables deep insights into past and current surface processes and paleoclimatic evolution.
In this contribution we give an overview on the EPR method and its challenges and we present kaolinite EPR data from 28 samples deriving from two deep lateritic profiles developed throughout the Cenozoic on top of Paleoproterozoic schists of the Guiana shield. Comparison with geochronological constraints from (U-Th)/He dating on iron oxides and oxyhydroxides [2] of the same profiles allows a contextualization and a discussion of the ages, which enables a deeper insight into the evolution of the lateritic profiles.

[1] Allard, Thierry, et al.(2025) "EPR dating of clay minerals formation through geological times: benchmarking from the Quaternary to the Neoproterozoic era." American Journal of Science (325), 6

[2] Heller, Beatrix M., et al.(2022) "Reading the climate signals hidden in bauxite." Geochimica et Cosmochimica Acta (323), 40-73.

The Münchberg Massif consists of four metamorphic nappes, which show different metamorphic grades in inverse order. The lowermost nappe, the Prasinit-Phyllite-Serie, is of lowest metamorphic grade (greenschist facies) containing mainly phyllites and greenschists with intercalated serpentinite bodies. Serpentinization, a water-rock reaction, can generate molecular hydrogen (H₂), a potential energy carrier. These serpentinites, however, have received limited attention.

Hydrogen is a molecule with very low diameter, which might escape after serpentinization. Understanding the timing and conditions of serpentinization is thus essential for evaluating the preservation and potential of natural hydrogen accumulations. As part of the Prasinit-Phyllite-Serie, serpentinization could have happened at different stages: in the mantle during subduction, during obduction, or during the different stages of the uplift of the Franconian Line. To relate the serpentinization to any of these stages, the age of the newly formed minerals, such as serpentinite or magnetite, is of importance. Therefore, magnetite and some serpentine were analysed by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) for their U, Th and Pb isotopic composition to constrain the timing of serpentinization.

Although the content of U, Th and Pb was low, the results of these measurements show a defined age range, which lies in the range of the ages of the Prasinit-Phyllite-Series and the Randamphibolite, which are supposed to be part of the Rheic Ocean (Koglin et al. 2018). Such ages older than the main stage of the Variscan Orogeny also indicate a serpentinization and hydrogen formation in the mantle beneath the Rheic Ocean.

The Adula nappe, Lepontine Alps, Switzerland and Italy, was shaped in a south-dipping subduction zone during the Alpine orogenic cycle. It comprises crustal gneisses, metasediments, and mica schists, as well as eclogites, amphibolites and peridotites. Rocks from the Adula nappe record a gradual increase in pressure and temperature from north to south with high-pressure (HP) metamorphism followed by low-pressure (LP)/high‒temperature (HT) conditions. HP metamorphism and the subsequent LP-HT overprint are considered to reflect a single P‒T evolution. However, geochronological data from the Adula nappe indicate Variscan and Alpine metamorphism. The P‒T conditions recorded by the Adula nappe are thus attributed to Variscan-Alpine polymetamorphism and a polyphase Alpine deformation history, which obscured the mineral equilibria developed during each high-grade event.

In this contribution, we investigate the U-Pb systematics of polymetamorphic garnet from the Adula Nappe by LA-ICPMS. We furthermore explore the U-Pb dates of U-rich inclusions in garnet to constrain their entrapment and formation history and thereby complementing the age information obtained from garnet. The location of the laser spots analyses is guided by BSE imaging, which resolves different garnet growth zones.

Our preliminary results indicate a plethora of internal garnet textures, that document the fragmentation of Variscan garnet and subsequent Alpine overgrowth, amongst others. Moreover, U-Pb dating of the accessory phases in garnet reveals that Variscan garnet also contains Alpine-aged inclusions.

The Fiskenæsset Complex of Greenland with an inferred metamorphic age of 2.7–2.5 Ga hosts one of the oldest ruby deposits in the world, named Bjørnesund. Although it was discovered at the end of 1970s, the exact time of formation and genesis of this deposit are still poorly known.

Ruby mineralization occurs in mica shists hosted by anorthosites of the Fiskenæsset Complex. In situ SIMS U-Pb dating of rare rutile inclusions within ruby crystals yielded concordant ages averaging 2482 ± 37 Ma (95% confidence; n = 4; mean square of weighted deviates = 0.45), which to the best of our knowledge is the first U-Pb age for rocks from this area. Applied geothermobarometric methods indicated that the formation of ruby-bearing rocks occurred at temperatures of ~710–730°C based on Zr-in-rutile thermometry and at maximum pressure of 400 MPa. Trace element ratios within ruby such as Ga/Mg, Cr/Ga, Fe/Ti, and FeO-Cr2O3-MgO-V2O3 (wt.%) vs. FeO + TiO2 + Ga2O3(wt.%) commonly used as proxies to identify corundum origins correspond to a metamorphic signature. It implies that formation of this ruby deposit may be linked to regional metamorphism during the Neoarchean which overprinted the Fiskenæsset anorthosite complex.

Opal (SiO₂ • nH₂O) is one of the few non-crystalline minerals. Due to its amorphous nature, high porosity, arrangement in spheres of silica nanograins, and elevated H₂O content, it poses significant challenges for radiometric dating. Consequently, opal has rarely been used as material for dating purposes, although it occurs relative widespread in both sedimentary and hydrothermal environments. Here we present results of U-Pb dating of black opal (pigmented by organic matter), which occurs in miarolitic pockets of pegmatitic rocks within the Precambrian Korosten Pluton (Western Ukraine). The opal formation age is of particular interest, as these pockets also host the Volyn biota (Franz et al. 2023, doi.org/10.5194/bg-20-1901-2023, see talk in session 01.10).

U-Pb dating was carried out by LA-ICP-SF-MS at KIT (Karlsruhe) on three different samples, using an ELEMENT XR (Thermo-Scientific) coupled to a 193 nm Excimer laser. Opal from a Li-mica-rich domain, with very low common Pb content, yielded a Triassic age of 201+8/−14 Ma, reflecting the minimum time of opal formation. In contrast, opal from alkali-feldspar-rich domains, which is always enriched in common Pb, yield Jurassic lower intercept ages of 168±6 Ma and 156±5 Ma, perhaps dating fluid infiltration. An altered opal crust gave a (sub)recent age, suggesting Pb-loss during a very recent hydrothermal overprint. The results show that LA-ICP-MS techniques provide a potential tool to place new constraints on the timing opal formation, fluid infiltration and alteration, and to gain new information about the late-stage hydrothermal evolution of the Eastern European platform.

This study examines the regional structure of the Zagros fold-thrust belt in Kurdistan, northern Iraq, utilizing field studies, remote sensing-GIS analyses, and cross-section restorations. The study area lies in the frontal zone of the north-western part of the Zagros fold and thrust belt in Kurdistan, near the north-eastern margin of the Arabian Plate. It is characterized by WNW-ESE striking, doubly-plunging, upright symmetric to asymmetric detachment folds that encompass 8.2–10.9 km of Paleozoic to Quaternary layers. Several regional structural sections were created, with a deep basal detachment identified at the base of the Paleozoic sequences. The area has experienced thin-skinned detachment folding along with thick-skinned thrusting from the Mid Miocene to the present. Detachment folding caused a maximum NNE-SSW-directed shortening of about 18.62 km (19.71%) over a section length of 94.45 km, while thrust faults resulted in a maximum shortening of around 1.98 km (1.95%) over a section length of 101.55 km.

The Makran Accretionary Wedge (MAW) in Pakistan and Iran, situated at the India-Arabia-Eurasia triple junction, provides a unique environment to investigate the mud-intrusive and mud-extrusive system (MIES) within an ultra-slow subduction zone. The MAW formed by northward subduction of the Arabian Plate beneath the Eurasian Plate, with convergence started during the Late-Cretaceous with a renewed phase since Middle-Miocene. This compressional regime has caused intense tectonic imbrication, deformation of pre-existing strata and formation of piggyback basins that preserved detailed records of tectono-sedimentary interactions. We utilized two-dimensional seismic reflection profiles, satellite imagery, and bathymetric data to map and characterize the geometry, spatial distribution, and connectivity of surface and subsurface mud-structures within the MAW. The MIES in this region form a complex plumbing system comprising mud-volcanoes (MVs), mud-diapirs (MDs), feeder-pipes, gas-chimneys, and mud-chambers etc., primarily sourced from the overpressured Makran Turbidite Deposits. These hemipelagic mud-rich deposits undergo compaction and tectonic loading, driving vertical and lateral fluid migration along structural conduits. Our study classifies the mud-structures into four types: (i) deep-sourced MVs, (ii) shallow-sourced MVs, (iii) multisource MVs, and (iv) multisource MDs. These structures typically exhibit conical, bifurcating, and Christmas-tree-like geometries with 75°–105° inclinations, commonly aligned with thrust-related anticlines, reflecting strong structural control. Active mud/fluid migration triggers coastal slope instability and normal faulting. Bottom-simulating reflectors further indicate ongoing fluid migrations and thermogenic gas generation within the MAW. The MAW, shaped by compressional tectonics and distinct sedimentary architecture, offers a valuable model for understanding mud-structures and tectonic processes in convergent margins worldwide.

The India-Asia collision, which started about 50 Ma ago, resulted not only in mountain building in the Himalayas. Recently about 50% of the total India-Asia convergence is accommodated in the Tian Shan orogenic system, far “behind” the collision zone. The start of uplift of the Tian Shan ranges is strongly debated. Most estimations, based on thermochronology, range from Oligocene to Late Miocene. The intermontane Ili Basin in southeastern Kazakhstan accommodates continuously clastic continental sediments since the Paleogene, recording the uplift history of the Tian Shan mountains. The basin is subdivided by young basement uplifts, providing good outcrops of the basin fill. The study of numerous sections revealed growth strata and progressive unconformities in different stratigraphic levels, specific for particular basement anticlines. First indications of deformation were observed already in late Eocene units. Uplift of basement anticlines and activity of thrust faults was interrupted by periods of tectonic quiescence and continuous deposition. Alluvial fan progradation documents uplift in the hinterland. Large alluvial fans were active during different periods, some disappeared and became reactivated. The basin fill documents asynchrony of growth strata, unconformities and alluvial fan progradation, proving spatially and temporally differentiated tectonic uplift throughout the Ili Basin. We explain the varying activity of structures by strain partitioning at major strike-slip faults or temporary locking of thrusts by the load of the hanging wall, possibly caused by low erosion rates during arid climate.

A safety case is a formal compilation of evidence, analyses and arguments that quantify and substantiate a claim that a repository will be safe. The description of the future evolution of a final repository system is a fundamental requirement for assessing its long-term safety and therewith part of the safety case. The deviation of future evolutions includes the analysis of relevant influencing factors and the uncertainties regarding the actual evolution of the final repository system.

The systematic determination of evolutions for a potential disposal site bases on a climatic and geological long-term forecast and a FEP catalogue (features, events and processes) for the respective site. For this purpose, the FEPs have to be classified according to their probability, their significance regarding their impact on safety functions, and based on regulatory requirements (FEP screening).

The objective of this project is the development of a comparable workflow for all host rocks and a rationale as to where this workflow must branch into different paths for various host rocks and emplacement concepts. Therefore, the project will focus on specific characteristics in the scenario development regarding the different host rocks and emplacement concepts. Subsequently, we plan to compile options for host rock specific standardizations for the methodology and to compare existing national and international workflows for the derivation of evolutions. The project therefore serves to harmonize scenario development in the course of the site selection process in Germany, pursuant to the Repository Site Selection Act (StandAG).

Deep geological repositories for radioactive waste necessitate safety evaluations, which encompass assessing the possible leakage of radionuclides from the waste containers into groundwater. In this context, the retention of radionuclides through water–mineral interactions is considered. Calcite is of significant importance in this regard, as it (re)crystallizes under relevant physico-chemical conditions in groundwater and can incorporate significant amounts of radioactive elements, such as trivalent actinides (Am, Cm). In contrast to laboratory experiments, which are conducted over short time periods and under controlled conditions, this study investigates radionuclide uptake during solid solution formation in natural systems. This approach offers the opportunity to evaluate the stability of solid solution phases over geological timescales.

To investigate the incorporation of trivalent actinides into calcite, as well as their analog element La, natural calcite samples were obtained from the Wenzel mine in the Black Forest, SW Germany. High-resolution LA-ICP-MS analyses reveal that the enrichment of La in specific sectors of the crystal can exceed that of other sectors by more than a factor of over 200. A mass balance of monovalent and trivalent ions within the different crystal sectors shows that the incorporation of La is not compensated by monovalent ion substitution. Our results suggest that trivalent ions are more likely compensated by vacancies on divalent ion sites on specific crystal faces. The study shows that calcite plays a significant role as a sink for trivalent actinides, but this role is highly specific and depends on the characteristics of the respective crystal surfaces.

The Opalinuston Formation (OPA) is designated as host rock for the disposal of high-level radioactive waste in Switzerland. In southern Germany, it remains one of several potential candidates under investigation. For the present study, samples from the Mont Terri rock laboratory (Switzerland) and from the BGR project “Sequence Stratigraphy of the Aalenian in southern Germany” (SEPIA) were investigated using a facies-based approach including mineralogical and geochemical analyses. Particular emphasis was placed on the degree of ordering of the illite-smectite interstratified clay minerals (I-S), which are responsible for sorption of radionuclides and swelling properties.

The results support the classification of the OPA into several (sub-)facies types. The clay fraction present in the samples varies according to these facies types, consistent with variations in cation exchange capacity. For southern Germany, crystal structure-based Rietveld refinement indicates a proportion of illitic layers in the I-S averaging between 77% and 83% across all refinements and ordering types. No significant differences in the illite:smectite ratio of the I-S was observed between the two sites studied. However, a notable difference in the degree of ordering was identified. This variation can be attributed to differences in the burial history of the OPA at the two localities.

A preliminary comparison with results from the OPA in Switzerland reveals that the average proportion of illite layers in the I-S (approximately 77% for Mont Terri) closely aligns with the results observed in southern Germany. Our ongoing effort is to compare these results with crystal-structure based Rietveld measurements from other claystone formations.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany,” BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas (in claystone, rock salt, and crystalline rock).

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with a focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

Part II of this contribution describes the integration of different data for a geological interpretation of individual criteria in the preliminary safety assessments using the Zechstein rocks salts of the Thuringian Basin as an example. The assessment of the spatial geometry (thickness of the main geological barrier and minimum depth) as well as the internal configuration of the rock salt are important features that were combined in the categorizations for the Thuringian Basin, which were published as a preliminary working status in 2024.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany,” BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas (in claystone, rock salt, and crystalline rock).

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

The claystone succession of the “Upper Cretaceous” in eastern Germany has been designated as claystone sub-area. Based on borehole data and a published petrographical study, the sequence was characterized lithologically in order to define a succession with a barrier function within the stratigraphic sequence. The thickness of the actual barrier was important for the categorization of the sub-area. This poster explains the results that were already published as a preliminary working status in 2024.

Understanding the temperature field is essential for conducting safety analyses during site selection for a repository of heat-generating radioactive waste in Germany. The initial temperature distribution in the respective host rock determines the repository design. This information is also important for analysing possible future developments of repository systems regarding the safe confinement of radioactive nuclides. In the BGE-funded project ThermoBase, BGR and GFZ are collaborating to characterize the subsurface thermal conditions in regions with sedimentary host rocks, such as rock salt and claystone.

BGR carries out stochastic analyses of the influence of parameter variations on the temperature in the host rock and the overburden. Numerical repository system models of varying complexity are used for the safety-related assessment of the influence of the variance of thermal rock properties and boundary conditions on the temperature development in the final repository. First analyses provide insights into the effects of parameter variation on the thermal field.

GFZ is developing detailed 3D geological models for transient conductive temperature and heat flow simulations. New measurements of rock thermal properties are being conducted on core sections in the laboratory and derived from high-resolution geophysical logs. First results provide insights into the spatial variability of the thermal field and its implications for repository planning.

In the current phase of the German Site Selection Procedure for a deep geological repository, large areas of Germany’s subsurface are being screened in order to identify the most-suited regions. The portfolio of host rocks includes claystone, rock salt, and crystalline rocks. These geological formations can exhibit significantly different properties and key subsurface uncertainties relevant to a geological repository.

Additionally, in alignment with the regulations, only existing subsurface data are used during this screening phase, i.e., data acquired for other purposes, such as hydrocarbon, potash exploration, etc. Hence, the available dataset is heterogeneous, both in terms of data types and in terms of geographical distribution.

The estimation of the subsurface uncertainties is relevant for the robustness evaluation during the safety assessment. Consequently, the uncertainty estimation concept includes methods tailored for the specific requirements.

For large areas with heterogeneous data, a semi-quantitative method for a consistent and efficient assessment of the subsurface uncertainties was developed. This method estimates a “degree of confidence”, which represents the reliability of given statements concerning the interpretation of the subsurface. The “degree of confidence” will be assessed for all investigated sub-areas in claystone, rock salt (stratiform), and crystalline host rock. It comprises the combination of data quality and quantity, on the one hand, and the geological complexity, on the other. This contribution gives an insight into the method and the preliminary results.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany,” BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas (in claystone, rock salt, and crystalline rock).

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with a focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

Part I of this contribution describes important methods and criteria that are used to characterize sub-areas related to flat bedded rocks salts. Preliminary results are presented.

BGE (2020/88): Sub-areas Interim Report pursuant to Section 13 StandAG. Bundesgesellschaft für Endlagerung mbH (BGE). Peine: Bundesgesellschaft für Endlagerung mbH (BGE).

The safety assessment of a repository system for radioactive waste in crystalline rock depends to a large extent on the the fracture system and its properties. Calcite is the most common fracture mineralisation at many crystalline sites in terms of radionuclide retention potential. The aim of the planned work is to investigate calcite fracture mineralisation in crystalline rocks of the Odenwald Crystalline Complex with regard to their ability to retain radionuclides. The investigations will focus on radionuclide retention by incorporation, i.e. substitution of radionuclides in the calcite crystal lattice. Since it is not possible to study radionuclide retention in natural calcite fracture mineralisation, natural analogues are used for these studies. Due to similar chemical behaviour, the lanthanides (REE) can be considered as analogues for the trivalent actinides, and Th and U as analogues for the tetravalent actinides. By (1) analysing the concentrations of REE, Th and U in calcite and in the hydrothermal fluids or deep (palaeo-) groundwater from which the calcites were precipitated, and (2) investigating the physico-chemical formation conditions (e.g. temperature, pressure, pH) by fluid inclusion analyses, it is possible to estimate to what extent and under what conditions the formation of calcite can contribute to the binding of radionuclides in fracture mineralisation.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany”, BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas (in claystone, rock salt, and crystalline rock).

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with a focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

The claystone succession of the “Opalinuston Formation” in southern Germany has been designated as claystone sub-area. Based on borehole data, the sequence was mapped and described in vertical and lateral extend. This information was used to assess, for example, the thickness of the barrier and the maximum depth of the top of the Opalinuston Formation, which led to the categorization of parts of the sub-area in the first two steps of the preliminary representative safety analysis. This poster explains the results that were already published as a preliminary working status in 2024.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany,” BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas (in claystone, rock salt, and crystalline rock).

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with a focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

Part I of this contribution describes important methods that are used to characterize and assess the claystone successions present in the different sub-areas.

BGE (2020/88): Sub-areas Interim Report pursuant to Section 13 StandAG. Bundesgesellschaft für Endlagerung mbH (BGE). Peine: Bundesgesellschaft für Endlagerung mbH (BGE). https://www.bge.de/fileadmin/user_upload/Standortsuche/Wesentliche_Unterlagen/Zwischenbericht_Teilgebiete/Zwischenbericht_Teilgebiete_-_Englische_Fassung_barrierefrei.pdf

StandAG: Standortauswahlgesetz vom 5. Mai 2017 (BGBl. I S. 1074), das zuletzt durch Artikel 8 des Gesetzes vom 22. März 2023 (BGBl. 2023 I Nr. 88) geändert worden ist.

Li can be detected in salt rocks, although no known naturally formed salt mineral incorporates Li in the crystal lattice [1]. Very low Li concentrations (few µg/g) are related to fluid inclusions, but higher concentrations must originate from other sources, e.g. phyllosilicates [1, 2]. To verify the Li-hosted minerals, samples from the upper Staßfurt-Formation (Deckanhydrit, z2DA) to the lower Leine-Formation (Grauer Salzton, z3GT; Leinekarbonat, z3LK; Hauptanhydrit, z3HA) were investigated. The succession contains salt clays, anhydrite and carbonate bearing salt rocks of the Upper Permian (Zechstein) from the Morsleben site (Germany).

The samples were investigated using ICP-OES, ICP-MS, XRD, SEM and thin section microscopy.

The z2DA shows Li concentrations of ca. 4 µg/g to 159 µg/g. The sample with the highest Li content consists of quartz, illite-muscovite, chlorite (clinochlore), halite, anhydrite, magnesite, kaolinite, koenenite, biotite and hydrotalcite. The z3GT is composed of quartz, illite-muscovite, halite, sylvite, anhydrite, carnallite, hydrotalcite, chlorite (clinochlore), anatase, biotite and tourmaline, with a Li content of 146 to 154 µg/g. In the z3LK, the Li content varies from 11 to 46 µg/g and in the z3HA from 5 to 116 µg/g. Al, K and Rb show positive relations to Li in all samples.

In the z2DA, Li probably originates from illite-muscovite, in the z3GT probably from illite-muscovite and a Li-bearing variety of a tourmaline (elbaite). The Li content of these minerals will be verified in future work.

[1] Braitsch (1971) Salt Deposits, Their Origin and Composition 4, 297.

[2] Mertineit & Schramm (2019) Minerals 9, 766; doi:10.3390/min9120766.

The long-term and safe disposal of high-level radioactive waste remains a major concern in both scientific and public discussions. In Germany, the Federal Company for Radioactive Waste Disposal (BGE) is responsible for selecting a suitable repository. In the first phase of the site selection process, the BGE defined several sub-areas, seven of which lie within the crystalline basement. However, many of these areas lack detailed information on the mineralogical, geochemical, petrophysical, and mechanical properties of the crystalline rocks, limiting the ability to assess their suitability. To address this gap, the AMPEDEK project aims to build a comprehensive reference database for crystalline basement rocks in Germany. In the initial project phase, data from over 40 published sources were compiled and integrated. Subsequently, around 650 cylindrical plugs from drill cores and outcrops were systematically analysed for petrophysical, mechanical, thermal, and geochemical properties. Triaxial tests and thermal conductivity measurements were conducted at elevated temperatures (up to 275 °C) and pressures (up to 30 MPa) to simulate reservoir conditions. The resulting database comprises ~25,700 data points for up to 34 rock properties derived from over 8,200 samples across more than 3,400 locations in eight federal states. The results reveal a wide range and variability in rock properties, reflecting the geological complexity of Germany’s crystalline basement. Lithology-specific trends in density, magnetic susceptibility, and thermal conductivity were observed. HT/HP experiments show significant changes in permeability and thermal properties with increasing temperature and pressure, underlining the need for site-specific characterization.

According to the Repository Site Selection Act (Standortauswahlgesetz – StandAG), the German Site Selection Procedure is an iterative process and consists of three phases with increasing levels of detail in which the assessed area is continuously reduced during the process. Starting with an empty, so-called “white map of Germany,” BGE (implementer of the German Site Selection Procedure) completed Step 1 of Phase I in September 2020 with the submission of the Sub-areas Interim Report (BGE 2020/88), where BGE identified 90 individual sub-areas.

In Step 2 of Phase I, BGE aims to localize siting regions within the 90 sub-areas by applying preliminary safety assessments and other scientific criteria. Within the preliminary safety assessments, subsurface data are interpreted and the results documented. The workflow comprises the detailed characterization and interpretation with a focus on the host rock formation that acts as the main geological barrier but also considers the surrounding rock formations.

The claystone successions of the “younger” and “older” Lower Marine Molasse have been designated as claystone sub-areas. Based on mainly borehole data, the sequences were characterized lithologically in order to define a succession with a barrier function within the stratigraphic sequence. Also, the spatial geometry of the barrier (such as the thickness of the barrier and maximum depth of the top of the barrier) are important features that are used for the assessment and categorization of the sub-areas. The results for both sub-areas were already published as a preliminary working status of the preliminary representative safety analyses in 2024.

The study encompassed a detailed description of existing environmental ‎and ‎social baseline conditions based on conducted surveys, scoping of the anticipated ‎impacts, and description of the most significant ‎adverse impacts during ‎well construction and operations. The study area is part of ‎the Zagros Fold ‎Thrust Belt and represents the Low Folded Thrust Zone. ‎Vegetation cover in the ‎area is limited to the typically thin cover of native grasses and ‎herbaceous species. ‎

Field surveys for the project area identified 66 taxa that were observed in this ‎study. The ‎area lies within ‎the edge of an important flyway for birds, with at least 68 species ‎documented, ‎including residents and several migratory species. ‎

The potential impacts of the project on the environment and their significance ‎were assessed before the project development. The primary ‎environmental and social concerns associated ‎with hydrocarbon exploration in the ‎area were: Loss of ‎pasture for livestock, grassland steppe ‎habitat for ‎wildlife and displacement of ‎wildlife, and loss of productivity on ‎cultivated lands.‎ We found that the ‎impacts associated ‎with the project are; the risk of ‎wildlife mortality and displacement, human activity, exposure ‎to contaminants and ‎hazardous substances, the ‎potential for spills, produced water and drill cuttings, ‎and emissions including ‎dust and noise;‎ risks to ‎groundwater as a result of drilling ‎and waste management practices, ‎potential reduction in local water ‎resources as a ‎result of water withdrawals, increased traffic safety risk: and ‎impacts to socio-‎economic ‎and cultural well-being and cumulative effects, particularly where a ‎discovery is made.

Organic micropollutants are a growing environmental concern, due to their ecotoxicological risks and impact on human health. Aquatic environments are particularly vulnerable, receiving inputs from multiple sources, with pesticides from agricultural run-off and pharmaceuticals from wastewater treatment plant effluents being among the most frequently detected contaminants. In these ecosystems micropollutants undergo non-transformative processes such as sorption and dilution, as well as transformative processes like bio- and photodegradation. However, transformative processes under different environmental conditions remain poorly constrained, even though they determine the persistence of micropollutants and can lead to transformation products that are more toxic or mobile than their parent compounds. To assess the effect of varying environmental conditions on the biodegradation of selected micropollutants, degradation experiments were conducted in single and co-occurrence of the antibiotic sulfamethoxazole and the herbicide S-metolachlor. River water and sediment microcosms from agricultural and urban sites enabled the evaluation of the effect of different matrices, organic matter and oxygen availability on biodegradation kinetics and transformation pathways. Within these conditions the half-lives varied between 4.2 ± 0.1 days and persistence after 90 days for sulfamethoxazole and 37 ± 7 days to persistence after 284 days for S-metolachlor. The results indicated that the presence and type of sediments are key factors of biodegradation. Furthermore, the detection of 4-aminobenzenesulfonamide, resulting from the ε-cleavage of sulfamethoxazole, as the main transformation product exhibits a novel biodegradation pathway. These findings provide environmentally relevant insights into micropollutant transformation and highlight key factors affecting their dissipation in aquatic environments.

Karst phenomena are crucial in physical geography due to their reliance on field studies. There's significant interest in limestone sinkholes in semi-arid environments, as they pose a major hazard to urban and infrastructure development, seen in areas like the Dead Sea coastlines and Florida, USA.

Egypt's El-Galala El-Bahariya Plateau, a semi-arid region, exhibits rocks affected by dissolution from groundwater and rainwater, along with chemical reactions impacting calcium carbonate. Satellite imagery of this area revealed a large, collapsed dissolution sinkhole. Field studies confirmed its location at about 700 meters above sea level, 3.25 km west of Porto Sokhna resort, and 4 km southeast of Galala city.

This sinkhole features a semi-circular opening with a diameter of roughly 30 meters and a similar depth, capable of accommodating a 10-story building with a volume of 21,195 cubic meters. The research explored the natural characteristics, factors influencing karst erosion, formation and development processes, and the resulting risks in arid and semi-arid environments, concluding with findings and recommendations.

Keywords: Karst Phenomena, Melting Hole, Diab Doline, Arid Zones, El-Galala El-Bahariya Plateau

The August 2022 forest fire event in the Harz National Park has suddenly shifted head water catchments to a new, unknown and short-lived state of equilibrium. The majority of standing bark beetle ceased trees were either burned or severely charred so that they fell in the weeks and months after the fire, giving way to the selective establishment of successive species. From studies in other fire-affected regions it was anticipated to see enhanced surface runoff and rain-driven sediment export. However, only little surface hydrophobicity was found months after fire, while measurements of diffusive fluxes out of the site are hard to constrain with typical state of the art approaches. Here, we present first results of the information that can be derived from a small seismic network in the Quesenbank site, a severely affected 12 ha patch in the Wormke headwater catchment on the southern slope of the Brocken towards the town of Schierke. In March 2024, we set up a triangular array of 4.5 Hz geophones with an aperture of about 100 m. We show successive changes in the response of soil moisture and deeper zone water dynamics to rainfall events and over multiple seasons. We use the array to detect and locate brief periods of seismic activity due to uprooting of trees and large branches falling off the dead trees, and compare the multi-seasonal evolution of event rates. We further inspect the state of coupling between atmosphere, biosphere and pedosphere by comparing meteorological time series and seismic ground response patterns.

Extreme hydrological events such as pluvial floods are increasing in magnitude and frequency due to environmental change, causing severe impacts on critical infrastructure and inhabited areas. However, it remains uncertain how extreme floods alter subsurface flow paths and sediment dynamics—and vice versa. Groundwater and the critical zone may play a key role in buffering the landscape response to such events. This study investigates subsurface responses to rainfall and flooding using passive seismic techniques, which use ambient seismic noise to non-invasively monitor subsurface water dynamics over time.

A network of ten seismic stations has been deployed across two sub-catchments in the upper Ahr Valley to measure relative seismic velocity changes (dv/v). These signals are used to infer temporal variations in subsurface water content, including groundwater fluctuations and vadose zone saturation. Seismic data are analyzed alongside environmental drivers such as rainfall intensity, soil moisture, river discharge, and groundwater levels. We focus on continuous data from May 2024 to June 2025, aiming to present dv/v responses to seasonal groundwater dynamics and to a 5-year flood event in January 2025, when the landscape was fully saturated.

This approach offers insight into the role of subsurface water pathways in shaping the hydrological and erosional response of upland headwater catchments. It supports the long-term monitoring of critical zone processes and erosion risk, and highlights the value of environmental seismology as a spatially integrative tool in hydrological research.

The Federal Company for Radioactive Waste Disposal (BGE) commissioned us to assess sinkhole susceptibility (1:250 000 scale) in areas relevant to the search for a final nuclear waste repository. In these areas favorable geological conditions for the safe final disposal of high-level radioactive waste can be expected. Each German geological survey contributes to geohazard mitigation within its respective federal states, addressing hazards such as sinkholes. To support this effort they document karst features in regional inventories. Our proposed work will be underpinned by these homogenized state inventories supplemented by data from selected publications with a connection to the geological surveys. Key parameters will be the general geological map of the Federal Republic of Germany (GUEK250), and the geological map of the Federal Republic of Germany (GK1000). These maps are supplemented with information from the borehole map of Germany and the geological 3D model of the deep subsurface in the North German basin (TUNB).
We differentiate between carbonate, sulphate and chloride karst. Each entry in the harmonized inventory is assigned a classification based on its karst type. Using geological maps, borehole information and TUNB we plan to derive binary maps showing the availability of soluble rocks for each karst type. These maps in combination with the karst type specific inventory allow us to delineate karst prone areas in Germany susceptible to sinkhole formation. Regional datasets will be used for validation through comparative analysis. To take into account regional variability we want to engage with local geological professionals from across Germany.

Floods are one of the most critical environmental threats in Central Europe. They are responsible for more than half of the economic damage caused by environmental hazards in Germany. The magnitude of the 2021 Ahr flash flood has far exceeded the values of previous flood hazard forecasts. This was due to significantly underestimated hazard assessments, as the former hydrological models considered exclusively instrumental discharge records. Due to the recording interval being too short, previous high-magnitude flood events were not considered in flood hazard assessments. Historical flood events from written sources were also not included in the official flood hazard assessment. In this study, we show the importance of geomorphological records from Ahr flood deposits for reconstructing past high-magnitude flood events. Our analysis shows that centennial to millennial-scale high-energy flood deposits are not the exception but the rule. In addition to the catastrophic flash flood of 2021, the historically documented flash floods of 1910 and 1804 were geomorphologically proven as well as a previously unknown flash flood event from the approx. 6^th century AD. The results document the high potential of floodplain archives for reconstructing high-magnitude flood events in Central European rivers, allowing a systematic reassessment in terms of occurrence and frequency of high-magnitude flood events.

The coastal dynamics of the Indian Plate span from rapid hydrodynamic events to multi-million-year tectonic cycles, recorded in its stratigraphy since the breakup of Pangaea (~200 Ma) into Laurasia and Gondwana. As part of Gondwana, its northward drift and interaction with the Neo-Tethys Ocean shaped a complex sedimentary history. Early Permian siliciclastics of the Paleo-Tethys gave way to carbonate-dominated Neo-Tethyan shelves, reflected in units like the Samana Suk and Datta formations. Mesozoic deposits such as the Shinawri (carbonate platforms), Chichali (lagoonal), and Lumshiwal (fluvial-deltaic) reflect environmental shifts, while the Kawagarh (micritic carbonates) marks carbonate productivity along basin margins. A major unconformity at the Cretaceous-Paleogene boundary signals the transition from marine Kawagarh to subaerial Hangu Formation (laterite/bauxite), linked to tectonic uplift and climate change during India-Eurasia convergence. Paleogene units like the Lockhart Limestone, Patala, Nammal, and Sakesar formations show evolving marine conditions, while the Kohat Formation records diminishing marine influence. Post-collision, continental sedimentation dominated, as seen in the Rawalpindi Group and residual marine carbonates (e.g., Gaj Formation). The Siwalik Group records Neogene-Quaternary fluvial deposition driven by Himalayan uplift, while the Chaman Belt Flysch captures late marine sedimentation from oblique convergence. This synthesis of stratigraphic and tectonic data reveals the Indian Plate’s evolving shoreline response to geodynamic thresholds. From Gondwana breakup to Holocene deltaic growth, the interplay of carbonate deposition, clastic influx, and basin shifts offers insights into ancient-to-modern coastal behavior, serving as a framework to predict responses under future climatic and anthropogenic pressures.

The Parallelodontidae is one of six families of the Arcoidea that is assumed to range from the Devonian to the Recent. Despite over 150 years of research, the origins and early history of the family remain largely unresolved. We reviewed the Devonian taxa that match the typical parallelodontid morphology regarding hinge details or external shell characteristics, leading to a list of some 50 species. However, most of them can only be vaguely attributed to Parallelodontidae, as poor preservation can obscure diagnostic features, causing potential confusion with contemporaneous genera showing comparable characteristics.

Here, we present details of the Devonian species that show parallelodontid morphology in the strict sense. All Ordovician and Silurian taxa previously attributed to Parallelodon or presumed to possess parallelodontid characteristics turned out to be misclassified. Parallelodon mandelensis from the upper Emsian Rhenotypic Facies of Germany undoubtedly has a parallelodontid hinge and seems to be the earliest member of the family. Next unequivocal parallelodontids have been noted in the Middle Devonian, primarily in the shelf region deposits of the Rheic Ocean in Central Europe and eastern North America, where up to ten species were identified. The relatively high sea level and, accordingly, wide shelf areas during this period provided ideal conditions for the diversification of parallelodontids. The Late Devonian evolution of the group is mainly documented in North America, as facies conditions in Europe seem to have been unfavorable. With the transition from the Devonian to the Carboniferous, a remarkable radiation of parallelodontids led to significantly higher parallelodontid diversity.

The Elbingerode reef complex is a large Devonian reef system in the central Harz Mountains of Germany. It is well known for its massive, thick and fossil-rich limestones that formed an oceanic barrier reef system in the Rhenohercynian Basin of the Paleotethys Ocean. The initial reef building of this barrier reef system is less well known, but exposed in the form of small outcrops at the boundaries of underlying volcanic rocks and superposed reef limestone. Also, waste rock piles of ore mining have contributed to the knowledge of these deposits, especially to their fossil content. These limestones have been revisited and investigated with regard to sedimentology, mineralogy, and biostratigraphy. The initial reef building is reflected in the occurrence of biogenic packstones, grainstones, and wackestones deposited in close relationship to volcanic activity. The limestones are rich in crinoidal debris (as the main constituent particle), brachiopods, rugose and tabulate corals, stromatoporoids, bryozoa, trilobites, tentaculites, ostracodes, conodonts, goniatites, and holothurians. Clasts of volcanic rocks are common. The fine-grained matrix of the deposits contains 60-80% carbonate and considerable amounts of non-carbonate fines. Reef frameworks did not form, but the common occurrence of numerous organism groups underlines that a highly diverse fauna had developed in a stressed environment including volcanic activity, and likely elevated turbidity and reduced water transparency. The textures and fabrics encountered suggest deposition below the fair-weather wave base, i.e., in water depths of several meters to a few tens of meters, however, not in shallow, agitated water.

Baden-Württemberg, as one of the most important industrial states in Germany, has a high volume of unavoidable CO₂ emissions. These emissions may originate from the production of cement clinker, paper, and glass, as well as from waste incineration or agricultural activities. To maintain the current level of industrial performance while meeting the climate goals of the European Union and Germany, Carbon Capture and Storage (CCS) could be implemented. Baden-Württemberg has the potential to store CO₂ underground, and in several cases, large-scale emitters could be directly connected to CCS facilities, avoiding the costs and energy required to transport CO₂ to the North Sea. Our study integrates the geological characterization of potential CO₂ reservoirs in Baden-Württemberg, with particular emphasis on sealing rock formations with an assessment of the available and future pipeline network that links the largest emitters to the nearest reservoirs within the state.

High-resolution stable isotope (δ¹⁸O, δ¹³C) data of 7000 to 6000 year-old oyster shells from the Yangtze River Delta constitute a combined record of climatic and oceanographic patterns (see Alberti et al., 2024). The results reflect prominent seasonal changes in temperature, precipitation, and river discharge. Summer months experienced warm temperatures and a distinct increase in rainfalls and river discharge. In contrast, winter months were dry and characterized by cool temperatures causing growth breaks in the oyster shells. Furthermore, the stable isotope analyses indicate regular summer upwelling in the study area during the mid-Holocene. Finally, the presented palaeo-proxy data offer the opportunity to evaluate available climate models for the region and thereby improve predictions for the future.

Alberti, M., Veiga, S.F., Chen, B., Hu, L., Fang, Z., Zhou, B., Pan, Y. 2024. The Yangtze River Delta experienced strong seasonality and regular summer upwelling during the warm mid-Holocene. Communications Earth & Environment 5: 492.

Phosphoric acid digestion of carbonates is associated with fractionations of both bulk oxygen and clumped isotopes. Accurate knowledge of the effect of cation substitution on the degree of isotopic clumping in the carbonate phase (∆₆₃, ∆₆₄) and on acid fractionation factors (∆^*₄₇, ∆^*₄₈) is crucial for accurate temperature reconstructions based on clumped isotope measurements (∆₄₇, ∆₄₈) of the extracted CO₂. Previous studies have yielded contradicting results whether a universal ∆^*₄₇ acid fractionation factor and ∆₄₇-T relationship is valid for all carbonate mineralogies, and a systematic investigation of mineralogy-specific effects on ∆₄₈ and ∆^*₄₈ is still lacking.

We have determined ∆₄₇ and ∆₄₈ values of stochastic (i.e, ∆₆₃ = ∆₆₄ = 0) and non-stochastic calcites, aragonites, dolomites, witherites‚ and siderites with outstanding precision. We demonstrate that stochastic calcite, aragonite, dolomite, witherite and siderite exhibit statistically indistinguishable ∆_{47, CDES90} and ∆_{48, CDES90} values. In addition, ∆_{47, CDES90} and ∆_{48, CDES90} values of non-stochastic aragonites, (proto-)dolomites and witherite correspond to calcite equilibrium values^[1] predicted by their independently known formation temperatures. These results provide evidence that calcite, aragonite, dolomite and witherite share indistinguishable ∆^*₄₇, ∆^*₄₈ and equilibrium ∆₆₃-∆₆₄-T relationships. Consequently, the calcite-specific equilibrium ∆₆₃-∆₆₄-T relationships^[1] can be reliably applied to aragonite, dolomite, and witherite. More investigations are necessary to clarify its validity for siderite.

^[1]Fiebig, J. et al. Chem. Geol. 670, 122382 (2024)

Reconstructing ancient ocean redox conditions is essential for understanding the link between marine anoxia and environmental changes. The Early Jurassic experienced significant oceanic redox fluctuations during the Pliensbachian/Toarcian event (Pl/To; ~184 Ma) and the more pronounced Toarcian Oceanic Anoxic Event (T-OAE; ~183 Ma). However, the expansion and connectivity of anoxic waters, e.g., in the European epicontinental seaways (EES), remain poorly understood. Here, we aim to apply U and Mo isotopes on carbonates and black shales that have become a powerful geochemical proxy for tracking redox changes at both local and global scales, combined with other redox-sensitive trace elements and REY, to unravel the oceanic redox evolution of the Early Jurassic.

Carbonate sediments investigated here are from Peniche (Portugal) and Toumliline (Morocco), covering both the Pl/To and T-OAE intervals. Shale-normalized rare earth element and yttrium patterns in the Peniche samples are characterized by negative Ce, positive Gd, and positive Y anomalies, indicating precipitation from open marine seawater. Recent data from near-contemporaneous Italian carbonate deposits suggest more extensive global seafloor anoxia during the T-OAE [1]. Our preliminary data, however, do not show negative U isotope shifts in the Peniche section suggesting that there was no global expansion of seafloor anoxia during either the Pl/To event or the T-OAE. Complementary U data of the Morocco section and coupled Mo-U isotope data from three different basins of the EES may clarify whether the redox shifts occurred contemporaneously and whether they represent a local or global phenomenon.

[1] Remírez et al. (2024), PNAS, 121(27)

The response of ice sheets and sea level to a warming climate is of global concern, with significant implications for human populations. To better understand these dynamics, especially during climates warmer than today, this project reconstructs sea-level and ice-sheet variability across six glacial-interglacial (G-IG) cycles of the late Cenozoic (~5 Ma), spanning the transition from the Pliocene greenhouse to the Pleistocene icehouse.

We use paired measurements of benthic foraminiferal δ¹⁸O and Mg/Ca ratios to reconstruct bottom-water temperature (BWT) and derive seawater δ¹⁸O (δ¹⁸Oₛw), a proxy for global ice volume. While effective for interglacials, the Mg/Ca proxy likely overestimates glacial lowstands due to non-thermal effects. To improve reconstructions, we integrate carbonate clumped isotope (Δ₄₇) thermometry, a seawater chemistry-independent BWT proxy, using material from Eastern Equatorial Pacific ODP Site 849. Though analytically demanding, Δ₄₇ offers a critical calibration check for Mg/Ca-derived BWTs.

Preliminary paired δ¹⁸O-Mg/Ca data from Oridorsalis umbonatus (3.35–2.0 Ma) at sub-millennial resolution reveal G-IG sea-level cycles with glacial lowstands lower than previous estimates. Δ₄₇-BWTs, available at lower resolution, broadly support the Mg/Ca-based reconstructions, reinforcing their validity despite limited precision and resolution.

Future work will refine the understanding of discrepancies between Mg/Ca- and Δ₄₇-derived BWTs, improving glacial sea-level estimates. This study aims to constrain sea-level variability rates and assess existing reconstructions, offering a more robust understanding of past ice-volume dynamics and informing projections of future sea-level rise.

The application of the triple oxygen isotope systematics (Δ’¹⁷O) to carbonates has emerged as a powerful tool for reconstructing past hydroclimate dynamics and tracing the long-term oxygen and carbon cycles. Over the past decade, a wide range of analytical techniques has been developed to determine the Δ’¹⁷O value of carbonates. Most methodologies involve phosphoric acid digestion, a process introducing systematic oxygen isotope fractionation that varies with carbonate mineralogy. While oxygen-18 fractionation during acid digestion is well known, the corresponding effects on oxygen-17 remain poorly constrained for many carbonate phases. This unknown factor, is likely to contribute to interlaboratory variability in measured carbonate Δ’¹⁷O values, limiting the reliability of cross-study comparisons and raising concerns about the accuracy of reported Δ’¹⁷O values, particularly when mixed carbonate phases are involved. In this study, we characterize the oxygen-17 acid fractionation factor θ_{(CO₂–acid/CaCO₃)} for a range of carbonate minerals, including calcite, aragonite, dolomite, and witherite. Instead of relying on quantitative fluorination, we apply a new technique to determine the oxygen isotope composition of the carbonate phases. This method combines high-temperature conversion elemental analysis (TC/EA) with high-voltage glow discharge to achieve quantitative oxygen extraction from carbonate as CO and its subsequent conversion to CO₂. We compare the δ¹⁸O and Δ’¹⁷O values of the resulting CO₂ with those obtained via carbonate acid digestion at different temperatures. All measurements were performed using laser absorption spectroscopy (TILDAS). The results of this study will provide critical reference data to improve standardization, interlaboratory reproducibility and interpretation of carbonate Δ’¹⁷O values.

Oil and gas exploration activities of the past century have left the Mackenzie River delta of the Canadian Northwest Territories dotted with more than 200 drilling mud sumps. These sumps are pits created by excavating the ground, placing drilling fluid wastes and drilled cuttings inside and backfilling with excavated material. The initial assumption was that the permafrost would provide a containment and prevent the escape of the contaminated material to the environment. However, as the Arctic warms due to climate change, it is uncertain whether permafrost will keep performing this containing role in the long-term. In this work, we monitor the apparent electrical resistivity of the shallow subsurface using repeat Electrical Resistivity Tomography (ERT) measurements in order to understand the freezing and thawing of the sumps. This also allows us to observe changes in the temperature and ice content of permafrost beneath the sumps and the surrounding tundra. We look at data collected from August 2023 until August 2025 from 4-day to seasonal intervals, examining changes of the sumps over time and contrasting them with the surrounding tundra. With our results we aim to shed light on the thermal effect these legacy contaminated sites have on the surrounding landscape and describe changes that might affect their containment function.

Thawing of permafrost in Alaska increases the risk of contaminant mobilisation into sensitive ecosystems and communities. Analysis of a contaminant site database reveals over 1,200 active contaminated sites on permafrost in Alaska—30% of which are military installations, containing up to 36 different pollutants. Hydrocarbons are the most abundant contaminants, followed by polycyclic aromatic hydrocarbons (PAHs) and other organic compounds. Though smaller but highly toxic groups of metals and pesticides can also be found on permafrost contaminant locations. Although many contaminants are poorly soluble, 40% of sites lie within 1 km of rivers or lakes, and over 70% within 1 km of the ocean—placing aquatic and coastal systems at risk.

Using the hydro-thermal model CryoGridLite, we simulate the future lateral contaminant mobilisation and hazard (CMPH) potential under SSP1-2.6 and SSP5-8.5 climate scenarios. We find that the Contamination mobilisation potential and hazard (CMPH) is projected to double by mid century, and possible triple by 2100 under high emission scenarios. While southern Alaska shows the highest absolute mobilisation due to deeper thaw, the coastal Northern regions see the largest increases in CMPH due to larger increases in active layer thickness.

This study provides novel insights into thaw-induced contaminant release. Communities, particularly Indigenous populations living near the coast and relying on local water and food sources, may face increasing exposure.

Accelerated climate warming in Arctic latitudes is leading to permafrost degradation, which is accompanied by rapidly changing landscapes. Thawing permafrost and thus related thermokarst processes have significant impacts on local ecosystems and existing infrastructure. Likewise, thawing permafrost threatens Arctic communities by increasing slope instability and potentially correlated displacement waves. However, scarce observational data limits our understanding of deep-seated landslide development in connection with fast thawing permafrost and thermokarst.

Forkastningsfjellet is a rapidly changing coastal mountain range, situated along the eastern margin of Isfjorden, Svalbard, which is affected by such thermokarst activity and rockslide driven coastline changes. Over the past 8 years, we have been documenting accelerating surface deformation and thermo-erosive activity, which in turn led to subsurface drainage, sinkhole and tunnel formation that lowered the stability of the permafrost bedrock of the cliff. The most recent rockslide in November 2022 was promoted by thawing of formerly ice-filled cracks and increasing pore water pressures within the strongly fractured bedrock. Due to continuing head scarp retrogression and ongoing gully formation along pre-existing zones of weakness, cliff collapse will most likely continue.

In order to achieve a better understanding of the process rates and the associated mass transfer, we use integrated, cross-platform datasets (drone imagery, satellite data, surface temperature measurements and differential GPS) to analyse the process dynamics, quantify rates of cliff top retreat and the correlated surface mass transfer. Our results are of fundamental importance for the understanding of future engineering geological hazard scenarios in Arctic coastal regions.

Climate change is already causing species to relocate in the Alpine region. To counteract current and future habitat loss, microclimatic refugia can play a crucial role. In this context, dolines are potentially valuable refugia. To assess their occurrence and distribution and thus support further research in their microclimatic potential, reliable mapping is required.
In this study, the fill-sink method for automated doline mapping was applied to a digital terrain model (DTM) of the Berchtesgaden National Park, which also provided the data. The results were compared with manual mapping. Additionally, the spatial distribution of dolines under the influence of topography (elevation, slope, exposition) was investigated to evaluate their microclimatic relevance.
The results show that the overlap between the two methods is small. A central problem of the method may be that it often combines several individual dolines into one higher ranked sink, likely due to the heterogeneous relief in the region. Nevertheless, the automated method identified margins of uvalas that align with historical maps. Based on manually mapped doline distribution only, we find a clustering of dolines at elevations between 2000 and 2200 m a.s.l, in low slope inclinations and on north-facing slopes.
Overall, reliable automated doline mapping needs to be adapted for regions with more complex relief. However, since other karst features with potential microclimatic importance were identified, the broader applicability of the fill-sink method should be further investigated beyond doline mapping. The current manually mapped distribution of dolines suggests future relevance for cold-adapted species and therefore requires further research.

Pleistocene climate change affects landscape stability in many ways and is reflected in sedimentary archives through phases of erosion, deposition and soil formation. Vegetation dynamics play a mediating role here: while established vegetation stabilizes the landscape when it’s within its climatic optimum, climate-induced vegetation shifts are characterized by ecological stress, turnover and the establishment of new vegetation forms, which promotes a phase of erosion. The landscape archive of Jojosi, KwaZulu-Natal, South Africa, is an exceptional site to better understand these dynamics. The site lies on the boundary between savanna and grassland, where a succession of sedimentary bodies indicates repeated phases of gully cut-and-fills since the Mid-Pleistocene.

We report on the results of several field campaigns in which we have stratigraphically correlated the Jojosi badlands, characterized them using geochemical and spectral properties, dated them using feldspar luminescence and measured their current erosion dynamics with UAV photogrammetry. Building on this, we used geostatistical models based on paleoclimate models to simulate the development of vegetation over the last 800,000 years. According to these models, the environmental conditions of the site oscillated back and forth between grassland and savannah over several climate cycles. The results suggest that past climate changes influenced the growing season length and fire regime, leading to non-linear, altitudinal shifts of the tree line, which promoted erosion and is reflected in the sedimentary succession. Our findings from the past allow to inform the future by inferencing our model to near-future climate scenarios to estimate related erosion risk.

Pakistan hosts diverse mineral domains with notable potential for lithium (Li) occurrences across multiple geological settings. In the northern regions, Li-bearing pegmatites and feldspar-rich granites are widespread, particularly along the Himalayan pegmatite belt that extends from Afghanistan through Pakistan to Bhutan. Two prominent sub-belts, Nuristan and Hindukush, contain rare-metal pegmatites associated with two-mica granites enriched in Li, Ta, Nb, Be, Sn, and Cs. In the Hindukush, the Garam Chashma and Miniki Gol granites are comparable to the Laghman Intrusive Complex in Afghanistan, showing significant Li enrichment (27.5–469 ppm) in non-pegmatitic samples and elevated concentrations of Be, Cs, Nb, and Ta.

To the east, pegmatites hosting Li-tourmaline (Elbaite) and Lepidolite occur in areas such as Shengus, Braldu, Haramosh, Kashmal, and Shigar valleys of Gilgit-Baltistan, and the Neelum, Muzaffarabad, and Kara valleys of Kashmir. Additional pathfinder minerals including pollucite, cleavelandite, aquamarine, beryllonite, and columbite in the Shigar and Rondu districts further support the Li-fertility of these pegmatites. Geochemical signatures of Shigar pegmatites—enriched in F, Rb, and Nb but depleted in Mg, Ti, Ba, Fe, Sr, and Zr—indicate advanced fractionation and lithium enrichment.

Two-mica granites of the Peshawar Plain Alkaline Igneous Province (PPAIP) also warrant exploration for Li-bearing pegmatites. Beyond hard rock deposits, the presence of lithium-rich hectorite in the clay formations of the Salt Range and potential lithium brines in closed-basin lakes such as Hamun-i-Lora, Hamun-i-Mushkhel, and the Rann of Kach highlight Pakistan’s multifaceted lithium resource potential.

Understanding the formation of Sn deposits, with cassiterite (SnO₂) commonly being the predominant ore mineral, is crucial for efficient mining and ensuring sustainable Sn utilization. Since cassiterite crystallization is accompanied by redox change from mainly Sn²⁺ in silicate melts (or fluids) to Sn⁴⁺ in SnO_2, and heavier tin isotopes preferentially bond to Sn⁴⁺, studying Sn isotope compositions may help track the redox conditions in the melt and/or fluid during Sn enrichment and cassiterite crystallization.

As a case study, we comparatively investigated the Sn isotope and trace element evolution of cassiterites from the rare metal granite system of Argemela (Portugal) and the greisen system of Sadisdorf (Germany). While in Argemela, Sn transport and cassiterite formation are thought to have mainly occurred by melts, metal transport and enrichment in Sadisdorf occurred during fluid-assisted processes.

Tin isotope and trace element analyses of individual zones reflecting different crystallization stages of the cassiterite grains were conducted in situ using femtosecond-LA-MC-ICP-MS. This method reveals conditions and evolution of the metal transport medium during cassiterite crystallization and ore formation.

Preliminary results indicate that cassiterite crystals from Sadisdorf have frequently high W concentrations and a trend from lighter Sn isotope ratios in the core towards heavier values at the rim, indicating increasing oxidizing conditions during crystallization. In contrast, crystals from Argemela mostly show high Nb-Ta concentrations and decreasing Sn isotope values from core to rim, possibly explained by Rayleigh crystallization. The ore-forming conditions in both localities will be further tackled by the investigation of Li isotopes in Li-micas.

The St. Andreasberg deposit in the Upper Harz region (Germany) is one of the most famous historical silver deposits worldwide. According to [1], the deposit was formed during four distinct mineralization stages, each characterized by differences in mineralogy, temperature conditions, and fluid composition. Antimony is one of the main components of each mineralization stage occurring as various sulfides (tetrahedrite, pyragyrite, and stibnite) and antimonides (breithaupite, and dyscrasite). Given the variable mineral assemblages and mineralisation stages, this deposit serves as a model system to better understand Sb isotope behaviour during the hydrothermal evolution of the mineralization.

In-situ Sb isotope analysis following the method of [2] show significant Sb isotope variations: The earlier (oxidic-carbonatic) stage and the main sulfidic stage show relatively constant δ¹²³Sb values of 0.2–0.3‰, probably related to higher formation temperatures. In the main arsenic-antimonide stage and the last stage, however, significantly more variable δ¹²³Sb values between 0.1–1.1‰ are reported, indicative of a late-stage overprinting by hydrothermal fluids. Antimony minerals associated with the early oxidic/carbonatic and the last stage are isotopically heavier than later formed minerals. This trend of decreasing δ¹²³Sb values can be explained by a Rayleigh fractionation model, resulting in a depletion of ¹²³Sb in the residual hydrothermal fluid during progressive crystallization. Our results highlight the applicability of Sb isotopes as a valuable tool to reconstruct the genesis and fluid evolution in complex hydrothermal deposits such as the St. Andreasberg.

[1] Ließmann (1997). Historischer Bergbau im Harz, Springer

[2] Kaufmann et al. (2021), JAAS. 36, 1554-1567.

Orogenic gold deposits are extensively studied as they account for more than 25% of the global gold supply. These deposits are found along a crustal continuum, from granulite to prehnite-pumpellyite facies rocks. The metamorphic devolatilization of metasedimentary and metavolcanic rocks at the greenschist-amphibolite facies transition is widely acknowledged as the primary source of fluids and metals for orogenic gold deposits up to amphibolite facies. At temperature above 600°C, however, this model is challenged as fluids may induce partial melting of quartz-feldspath-bearing rocks, consuming the fluids and preventing formation of deposits. Recent modelling suggests that komatiite — a significant but overlooked lithological unit in Precambrian greenstone belts — may generate auriferous metamorphic fluids up to the granulite facies and contribute to orogenic gold deposit formation.

The aims of KOMET² are to: 1) test the metamorphic devolatilization model applied to komatiite and investigate auriferous fluid production, 2) evaluate the contribution of komatiite devolatilization to orogenic gold deposit formation.

To achieve these aims, we will investigate metakomatiites in the Southern Cross and Kalgoorlie auriferous greenstone belts in the Yilgarn craton in Western Australia. By combining the mineralogy, whole rock geochemistry and thermodynamic P-T-X models of granulite to greenschist facies metakomatiite, we will characterize the behavior of metals, metalloids and ligands (e.g., As, Au, C, Co, Cu, Mo, Ni, Pt, S, Sb, Sn, Te) during prograde metamorphism and determine if an auriferous metamorphic fluid is produced. Orogenic gold deposits will be investigated to determine the link between metakomatiite devolatilization and ore formation.

Most of the world’s rhenium (~90%) is obtained from molybdenite (MoS₂) of porphyry copper deposits. The highest Re contents in MoS₂ were observed in the Cu-type deposits with smaller values in Cu-Au, Cu-Mo and Mo-W types deposits (Barton et al., 2020). The goal of this study is to determine the mechanisms leading to such fractionations.

To assess the role of salt and sulfur in the behavior of Re and the accompanying metals in supercritical fluids, we combined thermodynamic modeling with solubility experiments in aqueous salt-sulfur solutions at 400°C and 550 bar in the presence of pH, fS₂ and fO₂ mineral buffers. We measured the solubility of major ore minerals (CuFeS₂, MoS₂, ReS₂ and Au) in such fluids and critically revised the speciation models for those metals.

Our data show that Au and Cu form complexes with (HS)^– and Cl^– whereas Mo forms oxyanions and their ion pairs with K⁺ that is typical for other similar chemically “hard” metals like W (Borchert et al., 2025). Re in its common oxidation state +4 is expected to be a chemically “soft” metal and is likely transported by Cl- and S-type complexes.

Finally, we will present first results of complementary ab initio molecular dynamics simulations of Re speciation in aqueous fluids with different ligands, (OH)^–, (HS)^– and Cl^–, and discuss structural parameters and the geometry of the hydrated complexes in solution.

[1] Barton et al. (2020) Min. Metall. Explor. 37, 21-37

[2] Borchert et al. (2025) Eur. J. Mineral. 37, 111–130

Driven by the Critical Raw Materials Act and the associated search for raw materials in Germany, old Kupferschiefer mining districts are gaining the interest of research and exploration again. In the former Sangerhäuser district, the Kupferschiefer dips to the south and is dissected by faults separating different tectonic blocks. Consequently, the depth of the Kupferschiefer varies from bedrock outcrops immediately south of the Harz mountains to about 1000 m depth. Access to new sample material is difficult as the old mining fields are no longer accessible and have largely been flooded, but archived drill cores from before the 1960s exist.

Here, we report on examined drill cores from bore holes distributed over approximately 160 km². The data are used in order to better understand the lateral and vertical element distribution of critical elements such as vanadium, molybdenum, cobalt, nickel, and copper within the Kupferschiefer-type mineralisation. The element concentrations were determined using a portable X-ray fluorescence analyser.

The analyses of the drill cores clearly show that the mineralisation extends from the Kupferschiefer (T1) into the underlying footwall sandstone and the hangingwall Zechstein carbonate above. Based on preliminary data, the highest contents of copper are commonly found in the uppermost part of the sandstone or in the lowest parts of the Kupferschiefer. In some cases, however, the highest metal contents occur in the Zechstein carbonate. While vanadium appears to be mainly bound to the Kupferschiefer itself, measurable contents (<50 µg/g) of cobalt and nickel correspond mainly with areas of copper mineralisation.

The Kupferschiefer-type mineralisation of the Southern Permian basin in Poland and Germany represents the largest base metal mineralisation and resource in Europe. Outstanding scientific questions still to be solved include the spatial zoning of metals within some of the deposits and the mineralogical host phases of specific trace elements (e.g. Co, Se, Mo, V) that had been extracted in the past and still contribute to the economic potential of the mineralisation. This study investigates samples associated with the Kupferschiefer-type mineralisation of the Rotliegend sandstone, the basal black shale (T1) of the Zechstein, and Zechstein carbonates. The three lithotypes were continuously sampled along vertical profiles from underground exposures in the Röhrigschacht of the Sangerhausen mining district. Thin sections of the samples were examined by µXRF to obtain element distribution maps. Mineral assemblages and ore textures were determined by reflected light microscopy, BSE-imaging and EDS. The investigations confirm the classical base metal zoning from bottom to top: copper-lead-zinc, typical for the Sangerhausen district, but also reveal anomalous elemental distributions that deviate from expected patterns. In addition to common sulfide minerals (e.g., pyrite, chalcopyrite, bornite, galena, sphalerite), Pb- and Cu-chloride minerals of presently unclear origin were identified as carriers of value trace metals. Moreover, mineralised faults and the brittle-ductile deformation of ore minerals indicate the post-ore tectonic influence of the Upper Cretaceous Harz mountains uplift affecting the Wettelrode deposit. These findings provide new insights into the mineralogical complexity and the metallogenic processes of the Kupferschiefer-type mineralisation.

In some composite alkaline complexes, large amounts of ultramafic rocks occur together with melilitolites, carbonatites and other alkaline silicate rocks. These rock associations are of significant economic interest due to their common enrichment in critical and strategic elements like Ti, P, HFSE, or REEs. Key examples for such systems are the Gardiner (Greenland) and Kovdor (Russia) complexes. The timing of enrichment of HFSE during the evolution of these two complexes is still under debate. Carbonatites at Kovdor (Russia) are HFSE-mineralized, with only minor HFSE-phases in the associated silicate rocks. In contrast, melilitolites from Gardiner show ore-grade enrichment of perovskite, while the associated carbonatites are barren.

Previous work assumed similar parental melts due to similar homogenization temperatures and daughter mineral assemblages in olivine-hosted melt inclusions from ultramafic rocks. However, it was recently shown that dunites, peridotites, pyroxenites, and melilitolites from Gardiner represent orthomagmatic cumulate rocks, whereas some of the dunites and melilitolites at Kovdor are rather of metasomatic origin.

To reconcile these different origins, compositions and homogenization temperatures of crystallized melt inclusions from dunites, pyroxenites, and melilitolites are revisited in detail. Subtle differences in temperature and the abundance of carbonates and HFSE-phases in olivine-hosted melt inclusions from peridotites may display the metasomatic evolution. The comparison between the Gardiner and Kovdor complex will shed light on the nature of these rocks at variable evolutionary stages and the subsequent ore forming processes.

Monomineralic magnetite layers (MMLs) in mafic layered intrusions are a key global source of iron (Fe) and the primary suppliers of titanium (Ti) and vanadium (V). However, their formation mechanisms remain poorly understood. In this study, we examined drill core samples of Magnetite Layer 21 from the Upper Zone of the Bushveld Complex through detailed textural and mineralogical analyses. Petrographic observations reveal abundant plagioclase xenoliths and narrow plagioclase-rich layers within the magnetite layers. At the contacts between magnetite and plagioclase-rich layers, various symplectites (comprising olivine, plagioclase, amphibole, and biotite) and overgrowth rims (olivine and amphibole) rooted in Fe-Ti oxide grains are observed. Microprobe analyses indicate that the composition of primo plagioclase remains nearly constant (~An#54–56), while plagioclase in symplectites is significantly more anorthitic (~An#70–90). The Mg# of olivine and amphibole decreases from the rims toward the symplectites along the growth direction. Mass balance calculations suggest that these symplectites formed through reactions between primo plagioclase and Fe-rich immiscible melts. The presence of such melts is further supported by chilled margins within Magnetite Layer 21 and at its base, where fine-grained primo plagioclase with extremely anorthitic compositions (~An#90), extremely Fe-rich olivine (~Mg#30–35), and euhedral apatite assemblages are found. Based on mineral textures and compositions, we propose a new formation model for MMLs, in which Magnetite Layer 21 formed from Fe-rich immiscible melts that sank following the onset of immiscibility.

Hydrothermal deposits are formed by the precipitation of minerals from hot aqueous fluids circulating within the Earth's crust and are often associated with magmatic activity, e.g. VMS deposits on mid-oceanic-ridges. These deposits typically contain a variable amount of pyrite along with other metal-bearing sulfides. During hydrothermal alteration, interactions between sulfides and fluids can cause the formation of magnetite, thus indicating changes in fluid chemistry during the reaction. However, the conditions and replacement mechanism of this reaction remain ambiguous and need further evaluation. Therefore, we conducted experiments to analyse the conditions of this alteration and to constrain the lost of trace-elements into the hydrothermal fluid during pyrite replacement in a temporal evolution.

As starting material, equal mass amounts of natural pyrite (Panasqueira, Portugal) and deionised-water were filled into gold capsules and were exposed to hydrothermal conditions in an autoclave at 400 °C and 500 bar. We conducted the experiments for 3, 5, 7, 11, 14 and 21 days, followed by EDX, EMPA, ICP-OES and XRD. The first indications of magnetite formation were detected after 14 days characterised by a decrease of Fe-content in the fluid compared to the 7 days run and the detection of Fe-oxides by EDX. We assume that the Fe-concentration in the fluid stabilises at thermodynamic equilibrium. Analysis of the trace-element content in the fluid and on pristine and altered pyrites will constrain the trace-element release or partitioning at all time-steps.

Thanks for support to Maria Kokh, Wolfgang Morgenroth, Antje Musiol, Hans-Peter Nablein, Valby van Schijndel, Christian Schmidt.

Primary tin (Sn) deposits are commonly associated with highly fractionated, reduced granites derived from melting of evolved crustal rocks. While extreme fractionation is necessary to generate Sn-granites from low-Sn siliciclastic sediments (~5–10 ppm Sn), melting of Sn-enriched source rocks can yield Sn-rich magmas with minimal fractionation. We present an example of Sn-rich mica schists from the Bockau area, Western Erzgebirge that underwent metamorphic Sn enrichment prior to post-orogenic Sn-granite intrusion^[2]. Strata-bound Sn mineralization in the schists average 50–200 µg/g, with local concentrations up to 1 wt%. Microfabric analysis shows that Sn mobilization was linked to progressive deformation. Tin occurs in prograde minerals—biotite and garnet—as structurally bound Sn and as cassiterite (SnO₂) inclusions. A second phase of Sn mobilization is represented as secondary cassiterite inclusions during the retrogression of biotite to chlorite. Comparative whole-rock geochemical analysis of the protoliths^[1], Sn-rich non-retrogressed, and retrogressed schists reveal continuous Si addition throughout metamorphism and significant Fe and Sn enrichment during prograde metamorphism, accompanied by depletion of K, Rb, Ba and a relative decrease in the immobile elements, Al, Ti and Zr. Additionally, Li, B concentrations increased during the prograde and retrograde stages, respectively.

[1] Romer, R.L., and Hahne, K., 2010. Life of the Rheic Ocean: Scrolling through the shale record. Gondwana Research, 17(2-3), pp. 236–253

[2] Romer, R.L., Kroner, U., Schmidt, C., and Legler, C., 2022. Mobilization of tin during continental subduction-accretion processes. Geology, 50(12), pp. 1361–1365.

The Nkomati Ni-Cu-Cr-PGE Mine of the Uitkomst Complex in the Mpumalanga Province was the main primary nickel producer in South Africa until 2021, when the open-pit operation was placed on care and maintenance. The nickel demand generated by the EV battery market and the long-term increase of the Ni price may be reason to consider further detailed study of the petrology and alteration processes of the complex.

The lower three rock units of the about 2057.6 ± 0.7 Ma old (Maier et al. 2018) mafic to ultramafic complex contain Ni-Cu-PGE sulphide and chromite mineralisation. From bottom to top they are intensely saussuritizised, amphibolitised, serpentinised, talcified, and carbonatised. The original igneous cumulate mineral assemblage determines the composition of the alteration minerals, which in turn challenge ore processing of the unit. However, a positive correlation between the degree of alteration and increasing grade and aggregate size of the ore is obvious.

The formation of talc-carbonate schist is regarded as the ultimate stage of ultramafic rock alteration under the influence of a H₂O- and CO₂-rich fluid phase derived from pelitic and dolomite country rocks. These were strongly contact metamorphosed and partially assimilated by the ultramafic magma. Carbonate devolatisation provided the CO₂ for continuous talc-carbonate-alteration, from a late-magmatic to a hydrothermal stage. Pseudosections of CO₂ fraction vs. temperature phase diagrams allow the estimation of a formation temperature of about 500°C for the main part of the alteration paragenesis. The formation of the talc-carbonate-pyrite schist is regarded as a retrograde alteration process of serpentinised harzburgites.

The Late Permian Kupferschiefer in north-central Europe is one of the world’s most significant sediment-hosted stratabound copper (SSC) deposits, with mining of copper and other base metals dating back to the Middle Age (Borg, 2012; Paul, 2006).

Organic matter (OM) is thought to play a key role in the mineralization process, as previous studies have indicated pronounced alteration patterns in bulk parameters and non-polar biomarkers in mineralized rocks, using conventional analytical methods. However, subtle changes in organic composition may remain undetected using these approaches. Moreover, the exact mechanisms governing OM transformations during mineralization remain unresolved (e.g. Bechtel et al., 2002). Poetz et al. (2022) expanded the traditional approach by integrating polar compounds containing nitrogen, sulfur and oxygen (NSO) using high-resolution mass spectrometry (FT-ICR-MS), as these compounds are more reactive than hydrocarbons. They observed alteration of the oxygen containing compounds that correlated with the metal content but did not find significant differences in NSO compound composition between Cu mineralized rocks and Zn-Pb mineralized rocks. Building on this, we have analyzed samples with varying degrees of mineralization and thermal overprint by combining bulk and molecular parameters obtained through conventional analytical methods (GC-MS, GC-IRMS, ICP-MS, and Rock-Eval pyrolysis) with FT-ICR-MS data, aiming to provide a more comprehensive understanding of OM alteration and its dynamics during mineralization. Preliminary data suggest next to an enhanced OM alteration in the highly mineralized sample, an enhanced aromaticity which may resulted from oxidative processes.

Magmatic Fe-Ti oxide deposits are an important source of Vanadium, yet the mechanisms controlling V enrichment and redistribution remain debated. This study investigates vanadium-bearing titanomagnetite from two contrasting mafic intrusions in Québec, Canada: the layered Lac Doré Complex and the massif-type Lac Saint Jean Anorthositic Suite.

Both intrusions reveal complex lamellar exsolution textures, including trellis-, sandwich- and cloth-textured ilmenite intergrowths. These structures reflect two distinct exsolution pathways that operated under different thermal and redox conditions. Coarse ilmenite lamellae with trellis and sandwich intergrowths formed through high-temperature oxy-exsolution under super-solvus conditions, where magnetite became progressively oxidized. In contrast, subsolvus re-equilibration at lower temperatures produced typically cloth-textured ulvöspinel, which was subsequently replaced by fine-grained ilmenite during continuous cooling.

Electron microprobe and LA-ICP-MS analyses reveal systematic variations in TiO2, FeO, and Fe2O3 contents in titanomagnetite, reflecting magmatic differentiation and variable redox conditions. Vanadium distribution is closely linked to the ratio of Fe2+/Fe3+, with V preferentially incorporated as V3+ under moderately oxidizing conditions via coupled substitution with Fe3+ in octahedral magnetite sites.

During exsolution processes, vanadium becomes locally redistributed between magnetite and ilmenite lamellae. The observed textures provide a spatial record of this redistribution and demonstrate that both magmatic and postmagmatic processes influence vanadium partitioning between mineral phases. These findings have direct implications for the formation and economic assessment of vanadium-bearing Fe–Ti oxide layers in mafic systems.

By-products such as slag, sludge and fine dust from various iron and steel industries and foundries have high value due to their potential to recover iron and iron oxides as metallic iron, which can reduce the amount of waste sent to landfills and environmental pollution. In this study, different fine dusts and sludge were processed into agglomerates using a suitable reductant and formed via stamp pressing under varying contents and conditions. Instead of cement-based binders, biogenic alternatives such as potato starch, wheat starch and molasses oil were employed, and their influence on the mechanical properties of the agglomerates was examined, with the main emphasis on the cold compressive strength. Additionally, various amounts of fibrous materials were added to improve mechanical performance.

To optimize the mechanical properties, multiple recipes were systematically tested under different compaction pressures, binder compositions and curing conditions. The influence of fibre content and pressing parameters as well as curing time and temperature was evaluated to identify optimal combinations. The results show that biogenic binders, especially starch-based ones, in combination with fibre additives and an optimised curing, significantly enhanced the cold compressive strength of the agglomerates. The findings contribute to the development of sustainable, high-performance agglomerates suitable for industrial reuse and lay the foundation for further upscaling and application in metallurgical processes.

The reduction of metal oxides is crucial for the extraction of metals from their ores, a fundamental process in metallurgy. Growing demands within a rapidly transforming environment requires the development of innovative and sustainable solutions.[1] Mechanochemistry offers a solvent-free, energy-efficient route to materials processing, aligning with green chemistry principles.[2] By employing mechanical forces to induce chemical transformations, mechanochemical ball milling enables alternative reaction pathways, kinetics and alternative products.[3]

In this study, the mechanochemical reduction of metal oxides (e.g., Co₃O₄) is investigated through ex situ and perspectively in situ X-ray powder diffraction.[4, 5] A systematic study will explore the influence of metallic reductants (e.g., Mg, Al), gas atmospheres (e.g., H₂, NH₃), milling parameters (ball-to-powder-ratio, ball size, frequency), and jar/ball materials (e.g., steel, ZrO₂) on reaction mechanisms, phase evolution, and product properties. Metallic cobalt in both its cubic and hexagonal phases was successfully synthesized via ball milling, without the need for elevated temperatures or hazardous reducing agents such as hydrazine

This research advances the fundamental understanding of reaction mechanisms in mechanochemistry and supports the sustainable material processing. The results will contribute to critical topics such as green synthesis, recycling processes, and environmental aspects of material production. It addresses challenges at the interface of applied mineralogy, crystallography, materials science, and engineering.

1. Satritama, B., J. Sustain. Metall., 2024. 10

2. Mateti, S., Chem. Commun., 2021. 57

3. Takacs, L., Chem. Soc. Rev., 2013. 42

4. Rathmann, T., Rev. Sci. Instrum., 2021. 92

5. Weidenthaler, C., Crystals, 2022. 12

The strategic importance of lithium (Li) as a critical raw material for the global energy transition has tremendously increased in recent years. Several Li-bearing ore deposits have been identified in Ukraine, predominantly within the Ukrainian Shield and commonly associated with rare-metal pegmatites. The Polokhiv deposit, located in the central part of Ukraine within the Korsun-Novomyrhorod pluton, remains underexplored. To date, three ore zones have been delineated. Lithium mineralization at Polokhiv hosted in fine-grained microcline-petalite-albite metasomatites, with petalite accounting for estimated 95 wt.% of the total Li content.

Previous studies identified three morphological and textural generations of petalite. Generation I comprises coarse-grained crystals (up to 4 cm) intergrown with albite and microcline in an albite-microcline-petalite pegmatite. Generation II consist of micro-grained quartz-petalite aggregates that replace primary albite and microcline; symplectitic intergrowth of petalite with albite relics are also observed. Generation III is characterized by thin veinlets of petalite crosscutting the newly formed porphyry-like microcline. Preliminary tests have confirmed the potential suitability of using these ores for Li extraction.

Open questions concerning the genesis of the Li resources of Polokhiv deposit and the mechanisms of Li incorporation into ore- and rock-forming minerals will be addressed within a German-Ukrainian research collaboration between the Technische Universität Berlin and the National Academy of Science of Ukraine. Resolving these issues is essential for improving quantification of Li resources and for the development of efficient and sustainable Li extraction strategies.

With the planned phase-out of coal in Germany by 2030, fly ash—a widely used supplementary cementitious material (SCM)—will no longer be available. Among potential alternatives, activated clays have emerged as one of the most promising candidates due to their high pozzolanic potential upon activation. Structural damage enhances the reactivity of clays, enabling the silicon and aluminum components to participate in the formation of calcium aluminate silicate hydrate (C-A-S-H) phases in the presence of cement and water.

In this study, the phase composition and chemical properties of various clays were characterized via X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF) to determine the phase content and the silicon-to-aluminum (Si:Al) ratio, a key parameter governing pozzolanic reactivity. While most previous studies have focused on high-purity clays^[1], this work also investigates clay mixtures, comparing their behavior in cementitious systems to pure clays.

The activation process includes thermal treatment in a muffle furnace or mechanical treatment via grinding, both aimed at destroying the clay mineral structure. To optimize the thermal activation, decomposition temperatures were determined using differential scanning calorimetry and thermogravimetric analysis (DSC-TG). The pozzolanic reactivity of the activated materials was evaluated through isoperibolic heat flow calorimetry and the Frattini test according to DIN EN 196-5.

The results indicate that when the Si:Al ratio is nearly 2:1, the reactivity and hydration behavior of clay mixtures closely match those of pure clays, highlighting the potential of using mixed or impure clays as viable SCMs.

[1] Lagier et.al, Cement and Concrete Research 2007

The Fohberg phonolite, Kaiserstuhl Volcanic Complex (SW Germany), is a zeolite-bearing subvolcanic rock used as raw material for blended cement manufacturing. Rock-forming zeolites are of the natrolite group (natrolite, Ntr, and gonnardite, Gon) which amount to 45-50 wt.% of the bulk rock. The natrolite/gonnardite ratio, determined by powder X-ray diffraction (pXRD) and expressed as x_Gon = Gon/(Ntr+Gon), varies between 0.1 and 0.2 but may reach > 0.3 in exceptional cases. During industrial processing, the crushed rock is tempered in a rotary kiln at about 400 °C to enhance pozzolanic reactivity.

In-situ pXRD experiments (Bruker D6 Phaser equipped with Anton Paar BTS 500 heating stage) up to 460 °C were conducted to unravel mineralogical changes of the material during processing, and to detect structural changes of the zeolite constituents. Natrolite starts to convert to metanatrolite during heating at 380 °C; the phase transition is fully reversible. Gonnardite shows a strong, gradual decrease of the a-lattice parameter during heating, and becomes irreversibly unstable at 380 °C. The disappearance of gonnardite is accompanied by an increase of amorphous content of the sample. Structural changes are reflected by a distinct mass loss between 330 and 400 °C, related to zeolite dehydration. The other phonolite phases remain unaffected.

To test the pozzolanic reactivity, untempered and tempered phonolite samples with variable x_Gon were blended with a commercial CEM I 42,5 R reference cement. Indicators of reactivity are compressive strength and Ca(OH)₂ consumption (Frattini’s test). Results of the tests are shown and related to the pXRD experiments.

The Atacama Desert in Northern Chile, one of the driest places on Earth, provides a unique setting for studying organic matter preservation and microbial resilience in extreme aridity. Our project investigates the relationships among organic compounds, microbial communities, and mineral substrates across aridity gradients from the Coastal Cordillera via the hyperarid core to the foothills of the Andes. Its focus is on investigating surface crust formation, organic matter dynamics within these crusts, and the role of lithobiotic and endolithic communities in stabilising soil through interactions with mineral matrices. We combined gas chromatography-mass spectrometry (GC-MS) and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) to analyse lipid biomarkers and microorganisms, biofilms, and biominerals, respectively. First results reveal that surface crusts from areas receiving more than 5 mm of annual rainfall show a much higher diversity and concentration of sterols and fatty acids compared to areas with less than 2 mm of rainfall, reflecting differences in biological diversity, crust composition, and organic degradation. Halite crusts display lower lipid contents than adjacent soil crusts. Samples from the hyperarid core exhibit abundant aromatic hydrocarbons, suggesting atmospheric input and microbial degradation. SEM images reveal close microbial-mineral interactions and their agglutinating effect on mineral particles. Integrating biomarker data with mineral and microbial analyses aims at unravelling how biogeochemical processes, past hydrological episodes, and microbial activity simultaneously shaped the desert landscape, contributing to a broader understanding of carbon dynamics in extreme environments.

The Las Cruces gossan (Seville, Iberian Pyrite Belt, Spain) hosts a large cementation zone with abundant copper sulfides. Previous studies proposed that microbial sulfate reduction in the subsurface may have contributed to the secondary formation of these minerals^[1,2]. Here, we experimentally evaluated this hypothesis by investigating the potential role of sulfate reducing bacteria (SRB) in copper sulfide mineralization processes under conditions relevant to the Las Cruces gossan. More specifically, we established a geomicrobiological model system emulating the Las Cruces gossan subsurface environment. First, we exposed microbial enrichment cultures from sites characterized by moderate environmental conditions to 12.7 mg/L Cu at 40 °C for four weeks. Subsequent 16S rRNA sequencing revealed an increased relative abundance of several SRB (e.g. Desulfosporosinus, Desulfovibrio & Desulfitobacterium), which are also present in the Las Cruces gossan today^[2]. In further enrichments, different incubation temperatures and Cu concentrations were tested (see also abstract by Stoll et al.). We found that the SRB tolerated Cu concentrations of up to 38 mg/L at 40 °C. Subsequent SEM-EDS analysis revealed mineral-encrusted cell-like structures, together with colocalizations of Cu and S at or near these structures, potentially suggesting microbially mediated copper sulfide formation during the experiments. Although the observed mineralization could not be attributed to specific SRB, the results of our study lend support to the hypothesized microbial origin of copper sulfides in the Las Cruces gossan.

References

[1] Tornos et al. (2014) Nat. Commun. 5: 4600.

[2] Tornos et al. (2018) Geology 47 (2): 143-146.

Microbial sulfate reduction (MSR) may have played a major role in the formation of secondary copper sulfides such as covellite (CuS) and chalcocite (Cu₂S) in the cementation zone of the Las Cruces gossan (Seville, Iberian Pyrite Belt, Spain)^[1,2]. However, the formation of copper sulfides by MSR under conditions relevant to the Las Cruces gossan (e.g. hydrochemistry, temperature, pH) has not been experimentally evaluated yet. Using an established geomicrobiological model system for the Las Cruces gossan (see abstract by Schlund et al.), we explored MSR by tracking electron acceptor turnover (e.g. sulfate, phosphate) in incubation experiments over five weeks and by analysing yielded solid phases with SEM-EDS. Our data demonstrate significant MSR between 30–50 °C and even at high Cu concentrations (38 mg/L). Sulfate turnover increased with temperature (10 mmol/L at 30 °C, 17.3 mmol/L at 50 °C) and was highest in high-Cu experiments (20.1 mmol/L). Decreasing sulfate concentrations were accompanied by increasing phosphate concentrations and rising pH (4.5 to 7–8.5). SEM-EDS revealed the presence of copper sulfides in the experimental products, partially associated with C_org – similar to findings from the Las Cruces gossan^[2]. Taken together, our results support the hypothesis that Cu sulfides in the cementation zone of the Las Cruces gossan formed secondarily, driven by MSR. Moreover, our study contributes to a better understanding of the deep biosphere – including potential ore forming geomicrobiological processes in the shallow subsurface.

References

[1] Tornos et al. (2017) Mineralium Deposita 52: 1-34.

[2] Tornos et al. (2018) Geology 47 (2): 143-146.

Economic development requires substantial raw mineral resources. The construction industry, in particular, is dependent on the supply of domestic raw materials such as sand, gravel and clay. Monitoring the evolution of extraction sites is crucial for assessing current resource usage and future availability. The Landesamt für Umwelt - Bayern currently employs manual analysis of remote sensing data (e.g., aerial imagery, digital elevation models) and GIS software to classify open-pit mining regions as active or inactive – a resource-intensive process. This work presents a machine learning approach to partially automate this classification. We developed and trained a Random Forest model using existing manually-classified data. Initial validation demonstrates the significant potential of this methodology, achieving an accuracy exceeding 90% in preliminary tests. This contribution will demonstrate the first promising results of our automated classification system and discuss the challenges and future directions for model refinement and enhanced classification accuracy. This approach offers a pathway to reduce the resources required for monitoring mineral extraction activities.

The creation of a harmonised pan European geological map requires the agreement on a common lithological vocabulary. In practice, these are specific lithological concepts, ideally defined according to established and widely recognised classification schemes, represented by standardised labels.

Launched in 2022, the Geological Service for Europe (GSEU) project aims, among other objectives, to develop detailed, multilingual vocabularies for describing lithology, anthropogenic deposits, and lithotectonic units. These vocabularies are curated by international teams of GSEU members from across Europe. The challenge in creating a vocabulary suitable for harmonised mapping lies in reconciling differing classification schemes, addressing obsolete or regionally specific terms, accommodating multiple hierarchical structures, and incorporating genetically related terms, qualifiers, and compound names.

These challenges can be addressed through software applications that support visualising the hierarchical structure of the vocabulary and facilitate collaborative discussion. We present Vivity, a lightweight visualisation tool designed to plot hierarchies. It accepts Excel files as input, generates a tree diagram, and allows the user to export the plot as a PNG or SVG file. Additionally, factsheets are developed to represent each concept on an individual page. Ideally, each factsheet will be accompanied by an illustration that visually supports the concept’s definition and will be made available as a printable document. To achieve this, a Python script processes Excel files by converting them into JSON format, which is then used to generate LaTeX files and, ultimately, finalised PDF documents. Furthermore, the vocabularies are being tested against real-world use cases to ensure the concepts are practically applicable.

The Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung –BGE) has the task of evaluating Germany’s subsurface to find the location with the best possible safety for a deep geological repository for high-level radioactive waste. In this role, and during the current phase of the Site Selection Procedure, BGE collects and interprets data from existing sources in order to identify siting regions for surface-based exploration. In this contribution, we focus on methods to create transparency of the decision process in terms of the proposed siting regions, using the “BGE Repository Search Navigator” as a newly developed web application.

In order to achieve the goal of a transparent decision process, BGE started developing the BGE Repository Search Navigator in summer 2022. The navigator is an interactive, multimedia, and browser-based application for public information. The aim of the application is to make the process of narrowing down the sub-areas, published with the sub-areas interim report in 2020, to a few best-suited siting regions visible and comprehensible. The application provides information on the status of processing, the reasons for classifying an area from unsuitable to best suitability, and the general geology. BGE will publish preliminary working statuses annually to ensure that the work progress of BGE remains transparent to the public.

Until very recently, the word “archive” has often been associated with the connotation of a dark, dusty storage room with odd objects poorly maintained. Changing this perception and transforming an archive into a vivid, well-curated collection of samples for research, is a worthwhile effort that increases the value of each sample.

The Helmholtz Centres GEOMAR and Alfred Wegener Institute jointly develop research data infrastructure to keep track of the physical objects AND their associated data, using the open-source system LinkAhead. It hosts metadata of various sample types, such as biological and geological samples, taken at sea, on land and during ice expeditions. It ensures the unique identification of each sample and allows registration of persistant identifiers e.g. International Generic Sample Number IGSN as DOI via DataCite. Other export options serve for publications, to provide metadata to overarching platforms like the Marine Data Portal, and a link to the Nagoya documentation. Furthermore, a sample storage management with individual loan requests and lending documentation is incorporated.

In both Institutes, the database tool is in use as separate instances but with a common kernel, to allow for close collaboration and future joint developments. With these services to Earth and Environment researchers, we expand the F.A.I.R. data principles to the original physical material - make samples findable and facilitate their reuse - and want to encourage other dusty old archives to join the future of Geosciences.

Tropical high mountain ecosystems, including páramo grasslands, are highly vulnerable to climate change and important providers of biodiversity, carbon storage and water regulation. Paleoecological reconstructions that rely on environmental proxies such as pollen, charcoal or fungal spores preserved in lake sediments offer valuable insights into how ecosystems have responded to past climate changes and human activities. The Holocene, a relatively stable interglacial with significant human impact, serves as a key interval for investigating vegetation, climate and fire regime dynamics.

This study as a test case for the new EU COST Action PaleoOpen (https://www.cost.eu/actions/CA23116/), explores the potential of using the open-access and community-curated Neotoma palaeoecological database to integrate multiple local proxy datasets into cross-regional reconstructions of vegetation and fire dynamics in the montane forest and páramo ecosystems in the Ecuadorian and Colombian Andes.

We find that Holocene vegetational dynamics exhibit regionally divergent trends between Ecuador and Colombia, contradicting the initial hypothesis of coherent cross-regional climate signals within the tropical Andes. These results suggest either diverging regional climatic trajectories, potentially driven by Intertropical Convergence Zone (ITCZ) and El Niño-Southern Oscillation (ENSO) variability, or limitations due to insufficient spatiotemporal data coverage and high topographic complexity within the Andean region. Some fluctuations likely reflect diverse anthropogenic land use. These results highlight the need for enhanced spatial data coverage, alongside temporally and taxonomically harmonized datasets (a key challenge for PaleoOpen) to provide a better understanding of tropical high mountain ecosystem dynamics – essential for developing effective conservation and adaptation strategies facing accelerating climate change.

Present-day challenges in geothermal research, sustainable exploration, and energy storage require detailed information on the geological setting of the deep subsurface, which should be at the same time easily accessible and understandable. Generalized vertical profiles serve as essential tools for using this information during various project phases, from initial planning to geological interpretation or resource estimation.

Our study presents one approach to developing such profiles for representative subareas (TK25, TK50) in sedimentary basins in Saxony-Anhalt. Stratigraphy, temperature, and lithofacies are systematically compiled in comprehensive data sets based on borehole data, historical maps, literature values, and recently published 3D parametrized volume models of the TUNB project.

To ensure broad accessibility and practical usability, an interactive map is implemented, serving both as a visualization tool and a simplified, user-friendly database. Users can select an area to view column profiles displaying stratigraphy, temperature gradients, and lithofacies distribution. Planned features include statistical summaries and an optional expansion with block diagrams highlighting geological features.

Our approach offers an efficient framework for utilizing and providing different types of geological data. It supports future research and other geological activities, and is adaptable to other regions and data types.

The application of lead isotope ratios especially on non-ferrous artefacts evolved into the default method for the reconstruction of their raw material provenance. A pre-requisite for this method is the collection of data with known raw material provenance to which the artefact’s signature can be compared to. Unfortunately, the compilation and re-use of these data from literature is often hampered, among others, by the metadata’s large variety and different levels of detail. This does not only result in a time-consuming data compilation process but also limits, e.g., the implementation of machine learning approaches or large-scale meta studies.

The aim of TerraLID is to overcome the current state by developing a research data infrastructure through which lead isotope data can be published, stored, and accessed. It is complemented by a web application to work with such data, an online textbook which provides open educational materials on the topic, and a toolbox to facilitate re-use of the tools and templates developed for TerraLID. At the core of the data infrastructure is the TerraLID metadata profile to uniformly describe lead isotope data and contextual information. The TerraLID editors as community-representatives guided the development of this metadata profile and the entire community is currently invited to provide feedback on its draft. This contribution presents the structure of the metadata profile and how it connects to other metadata schemata and profiles.

Communicating the nuances of (possibly complex) 3D geological concepts via geomodels is a difficult task. No matter if you are introducing students to the numerous variants of earth's volcanoes at school, teach about different types of fault zones at university, or present your latest subsurface model to colleagues at a conference: The best way for them to explore and understand such a model is by observing and directly manipulating it themselves in 3D space (compared to 2D illustrations or animations).
This is often easier said than done because proprietary formats and software, or hard to meet hardware requirements make it cumbersome or even impossible to efficiently share 3D geomodels with a wider audience. As a mobile app, GST[AR] runs on commonly used hardware without the need for complex setups and thus aims to improve that situation by lowering the barrier of entry.
With this poster we want to shortly explain what GST[AR] does and how the underlying data structure looks like. To make GST[AR] available to a large user-base, workflows and tools will be presented that enable geomodellers to make their own subsurface models accessible via the app. Furthermore the poster will act as a firsthand example of how easy it is to give conference attendees direct access to these 3D models on their own device by making use of QR codes.

In the last decade, paleoseismological studies executed in northern Germany have extended the record of fault activity further into the past, partly leading to controversial discussions. Although it has been possible to identify GIA as a potential key trigger mechanism for the neotectonic, historic and recent fault activity in northern Germany, the major controlling factors for the distribution of tectonic activity are still underexplored. We investigate the basin-fill architecture and subsidence mechanisms of the Lehringen basin as a key example of an important Eemian archaeological archive. Based on the interpretation of shear-wave seismic sections, a ground penetrating radar (GPR) survey, borehole data, DEM analyses and numerical simulations of Coulomb failure stress, we assume that Eemian and Weichselian sediments near Lehringen were deposited in small fault-related basins that formed as a consequence of neotectonic movements along the Aller fault system. Two phases of subsidence can be derived, based on the seismic sections and the GPR survey, which points to two phases of fault activity after the late Saalian glaciation. This supports the idea that the Aller fault system is a glacially triggered fault and indicates that two separate phases of fault activity might have occurred. The identification of neotectonic activity on the Aller fault system has implications for a future seismic hazard assessment of Northern Central Europe and the definition of seismo-tectonic areas.

This study investigates the distribution, morphology, and infill of buried Pleistocene tunnel valleys in northern Germany and adjacent offshore areas, with implications for long-term safety assessments of radioactive waste repositories. Tunnel valleys, formed by pressurized subglacial meltwater, are prominent erosional landforms reaching depths of up to 600 meters b.s. Using the high-resolution 3D seismic dataset GeoBasis3D (2021), acquired in the German EEZ, we examine intersecting tunnel valleys, including one located above the Belinda salt dome.

The 3D seismic data enable detailed mapping of tunnel valley geometries and sedimentary facies. The lower parts of the tunnel valley are marked by steep flanks and chaotic internal reflectors, indicative of rapid, subglacial infill processes. Tunnel-valley infills reveal cut-and-fill structures, erosional unconformities, and parallel reflectors that indicate multiple depositional phases. Crestal faults above the Belinda salt dome displaced the tunnel-valley fill and locally reach the seafloor, confirming Pleistocene fault activity. However, fault activity did not impact the incision depth and only slighty affect the course of the tunnel valley.

On a regional scale, structural controls were evaluated by correlating tunnel-valley orientations with the trends of faults and salt structures. While some tunnel valleys align with (neotectonically active) faults, particularly where ice flow paralleled fault trends, no consistent correlation with salt structures was observed.

Our findings highlight the importance of integrating seismic stratigraphy and structural geology to understand tunnel-valley evolution. They also underscore the limited predictive value of structural trends for future subglacial erosion, which is essential for assessing repository site integrity over long timescales.

Accurate seismic hazard assessment in urban environments requires comprehensive knowledge of near-surface geological and geotechnical conditions, which significantly influence ground motion amplification. This study presents an integrated dataset to support seismic microzonation of the city of Aachen (Germany), focused on a 5 × 5 km² area targeted for its critical infrastructure and potential fault zones. The investigation incorporates 450 horizontal-to-vertical spectral ratio (HVSR) measurements, six microtremor array measurements (MAMs), six electrical resistivity tomography (ERT) profiles, and 175 geotechnical boreholes. These datasets enabled the spatial characterization of the fundamental frequency (f₀), the site amplification effects, and the Vs₃₀ values. Advanced interpretation methods were applied, including Rayleigh and Love wave dispersion analysis, Rayleigh-wave ellipticity, and horizontal-to-vertical time-frequency analysis (HVTFA). Furthermore, a two-dimensional numerical model of seismic wave propagation was developed along a southwest–northeast profile to simulate peak ground acceleration (PGA), identify amplification zones, and delineate subsurface stratigraphy and active fault geometry. The integration of ambient noise-based techniques with borehole and ERT data significantly improves the resolution of geological modeling in Aachen. The results provide essential input for future ground motion scenarios and contribute to the development of reliable urban seismic response models. This multidisciplinary approach supports risk-informed planning and enhances resilience in regions characterized by moderate seismicity.

We present a comprehensive update and improvement to the Paleoseismic Database of Germany and Adjacent Regions (PalSeisDB v2.0), compiling a broad range of paleoseismic records for Germany and surrounding parts of Central Europe. It compiles previously published and partly unpublished findings of paleoseismic evidence, complementing the short timespan covered by the region’s historical and instrumental earthquake catalog. Such limited coverage does not reflect the long seismic cycles characteristic of Central Europe. Hence, PalSeisDB was developed to document paleoseismic evidence, including data from trenches, soft-sediment deformation, and mass movements, thereby extending the earthquake record into pre-historic times documenting seismicity. This forms a key element for seismic hazard assessments. The first version of PalSeisDB provided evidence for multiple events in various locations within the region. Newly acquired information has now been integrated, revealing a broader distribution of paleoseismic features. We suspect that a considerable amount of evidence has not yet been discovered in detail, especially to characterize fault systems, which are often showing temporal and spatial clustering seismicity. In the updated version, paleoearthquakes have been evaluated and assigned to potential seismogenic sources, indicating seismic activity over geological timescales. The considerable increase in documented paleoseismic observations underlines the scientific importance of comprehending this study. Further developments for PalSeisDB include improving data structure, integrating historical seismic events with environmental earthquake effects, and implementing a public, web-based map interface. This updated resource aims to support ongoing research and facilitate collaboration among the geoscientific community, ultimately enhancing our understanding of seismic hazards in Central Europe.

Morphotectonic methods are commonly used to study landform evolution in regions with strong tectonic activity, like active plate boundaries. However, these methods are less often applied in low-strain but tectonically active intraplate areas such as the Lower Rhine Graben (LRG), even though the region has a history of recent and historical earthquakes. This study investigates how ongoing tectonic processes affect the landscape in the LRG. Using a 1-meter resolution LiDAR data, we applied GIS techniques, Topotoolbox (Schwanghart and Kuhn, 2010), and the SLiX model (Piacentini et al., 2020) to analyze lineaments, knickpoints, and key morphometric indices. These indices include the stream length-gradient index, hypsometric integral, basin asymmetry factor, valley floor width-to-height ratio, basin shape index, and transverse topographic symmetry factor. This study generated 53 knickpoints, and rose diagrams reveal identical trends between lineaments and existing faults. Further results show spatial correlation between anomalous indices' values, and knickpoints with existing fault structures and the generated lineaments. We interpreted the close location (< 600 m) of knickpoints to nearby fault structures, and their spreads at varied elevations to indicate 1) a passive or active tectonic control on landforms, 2) the influence of Variscan orogeny and glacial retreat on base-level changes in LRG, respectively. Finally, we used the Index of Relative Active Tectonism (IRAT), which averages all indices, to classify the region’s tectonic activity as moderate. Consequently, it was concluded that although the LRG is not highly deformed, moderate tectonic processes continue to shape its landscape.

The Federal Seismic Survey at BGR evaluates seismic events in Germany and neighbouring countries on a daily basis. The results are supplemented by the outcomes of the seismological agencies of the federal states of Germany and German universities and stored in an event database and in the German earthquake catalogue.

The events are classified as natural earthquakes, induced earthquakes or explosions (mostly quarry blasts). A considerable number of the events are induced earthquakes. They originate from stress changes due to human activities in the subsurface. The main causes of the induced events are coal mining, potash salt mining, natural gas extraction and geothermal energy production.

We describe the characteristics of the associated seismicity for the different mining regions in Germany. In contrast to natural seismicity which originates in long-term processes, the number and strength of induced seismicity is strongly dependent on rather short-term temporal and spatial changes.

The seismicity in coal mining regions, e.g., decreased coinciding with the shutdown of coal mining, whereas seismic activity in geothermal or natural gas fields show different behavior, increasing or decreasing depending on the location. Additionally, the latter both types of induced seismicity show remarkable peculiarities in their temporal behavior.

We show the temporal course of induced seismicity over the last 10 years in dependence on the distinct extraction types and compare it with the previous decades. In addition, we also investigate the magnitude-frequency relationship and the energy release of the induced earthquakes and compare the parameters with those of the natural seismicicity.

Both electron spin resonance (ESR) and optically stimulated luminescence (OSL) are dating methods that have been used to date surface-rupturing earthquakes along faults using gouges. Laboratory shear experiments have demonstrated that a complete resetting of ESR and OSL signals can be achieved by shear heating during faulting. However, ages obtained using OSL/ESR from fault gouges indicate overestimation of up to 2–3 orders of magnitude compared to the last known historical earthquakes along the faults. A possible explanation for this discrepancy is the incomplete signal resetting during faulting events.

In this study, we evaluate the conditions for partial thermal resetting of quartz ESR signals (Quartz - Al center) in fault gouge samples from the Periadriatic Fault (PAF) System in the Eastern Alps. The PAF is one of the largest post-collisional faults in the Alps, mainly active during late Oligocene–Miocene times, contributing to lateral extrusion towards the east. The seismic activity of the PAF has been debated but recent studies indicate that the fault hosted surface-rupturing earthquakes during the Quaternary.

Apparent ESR ages and signal thermal stability parameters were integrated to model the possible partial signal resetting conditions of the gouges due to seismic activity. Maximum shear heating temperatures were integrated using Raman spectroscopy of carbonaceous matter in the gouges. Our findings show that for the PAF the possible reset conditions are met at earthquake recurrence intervals in the order of 1-100 ka with shear heating temperatures below 350 °C.

The Upper Rhine Graben (URG) is the central segment of the European Cenozoic Rift System. The present-day stress field is characterised by an approximately NW–SE orientation of the principle stress axis σ¹, which is responsible for sinistral transtensional conditions that affect the URG system. In the southern eastern segment of the URG, seismic activity indicates that neotectonic processes are ongoing, shaping the present-day relief. This study focusses on neotectonics, tectonic geomorphology and the tectonic evolution of this region since the onset of the main URG rifting in the Early Oligocene. We combined remote sensing, fieldwork and geophysical measurements (GPR, ERT). Our analysis reveals that kilometre-sized fault-blocks of the Variscan basement tilt northeasterly. This can be inferred from the asymmetrical hillshape of the fault blocks, which are characterised by southward-shifted crestlines and larger local catchments on the northern with respect to the southern hillslopes. Triangular facets are aligned along both NW–SE and NE–SW trending valley sides in the Variscan basement. They are most notable at the western entrance of the Lower Münstertal near Staufen indicating active normal faulting. Riedel-shear fault patterns, bent and shifted creek beds as well as fault scarps in alluvial deposits of the Staufen Bay prove neotectonic activity of the eastern URG boundary fault. Faults have been (re-)activated with different kinematics at different times due to repeated changes of the regional stress field since the onset of the main rift phase of the URG in Early Oligocene.

Specific seismic hazard maps and detailed procedures for the calculation of seismic hazard are the basis of codes and rules which determine the construction and the operation of ordinary buildings and industrial facilities to withstand relevant seismic loads. The paper will primarily address the data foundations which are used to calculate seismic hazard, especially catalogues of paleo seismic data, historical seismicity and modern earthquake monitoring as well as further important input parameters. In Germany, Eurocode 8 and its German National Annex are used for most ordinary buildings. It contains a regional map of probabilistic hazard of Germany and a map of the geological underground classes to be used for local seismic hazard assessment. Earthquakes up to about 500 years return period are considered. On the basis of Eurocode 8, a related rule was developed to be used in case of chemical industry facilities. For nuclear installations there is a rule of the German Nuclear Technical Committee called KTA 2201.1 (‚Kerntechnische Anleitung‘). The specific requirements include the consideration of earthquakes with return periods of up to 100.000 years and the evaluation of local paleoseismic data. Long return periods are attributed to rarely occurring strong earthquakes and lead to higher levels of seismic hazard. Additionally, a code for different kinds of dam structures is used in Germany (DIN19700). Is is related to Eurocode 8 but requires longer return periods up to 10.000 years. Finally, the present requirements in the German selection process for a repository of high-level nuclear waste are summarized.

Die Geschichte der Sammlungen des Geologischen und Mineralogischen Museums in Kiel lässt sich bis ins 17. Jahrhundert zurück verfolgen. Erste öffentliche Ausstellungen erfolgten in unregelmäßigen Abständen seit 1846. Nach völliger Zerstörung des Instituts- und Museumsgebäudes im August 1944, erfolgte am 21. März 1970 eine Wiedereröffnung am jetzigen Standort. Heute gibt das Geologische und Mineralogische Museum einen Einblick in das vielfältige Fach der Geowissenschaften. Präsentiert werden unter anderem verschiedene Minerale, Gesteine, Meteoriten und Fossilien. Anhand der Sammlungsstücke wird der Aufbau und die Entwicklung der Erde und der Lebewesen erläutert. Ein besonderer Schwerpunkt liegt dabei auf der regionalen Geologie Norddeutschlands und des Ostseeraumes. Mit seinem Angebot richtet sich das Museum nicht nur an Studierende und Universitätsangehörige, sondern auch an Interessierte aus der Öffentlichkeit. Führungen und Veranstaltungen für Kindergärten, Schulen oder andere Gruppen werden regelmäßig durchgeführt.

Da die Ausstellung nicht durchgehend durch Personal betreut werden kann, bewegen sich viele Besucher*innen alleine durch das Museum. Um einen Besuch attraktiver und gewinnbringender zu gestalten, wurde mit Unterstützung des Inklusionsfonds der Universität Kiel ein Audioguide entwickelt zu den Kapiteln „Kristalle, Minerale und Gesteine“, „Meteoriten: Gesteine außerirdischer Herkunft“, und „Ein Gang durch die Erdgeschichte“. Zusätzlich wurde in Kooperation mit dem Institut für Leichte Sprache der Lebenshilfe Schleswig-Holstein eine Führung in Leichter Sprache entwickelt. Dieses Angebot soll Barrieren im Zugang zu Informationen reduzieren und Menschen einen Einblick in die Geowissenschaften ermöglichen, welche aus verschiedenen Gründen über eine geringere Kompetenz in der deutschen Sprache verfügen. Eine gedruckte Version der Führung in Leichter Sprache ist in Bearbeitung.

Bei der Gestaltung und Durchführung museumspädagogischer Programme gibt es einige Freiheiten und Vorzüge gegenüber dem Schulunterricht. Besonders bei dem Thema „Biologische Evolution und Geschichte des Lebens auf der Erde“ kann man auf eine große Fülle an Beispielen und auf aktuellere Konzepte wie Stammesgeschichte und phylogenetisches Denken („tree thinking“), Massenaussterben und Phasen der Erholung (recovery), Schlüsselinnovationen wie z.B. die Entstehung von Lichtsinnesorganen und der Fähigkeit zur Biomineralisation, evolutionäre Schranken, Ökosystem-Evolution, Superkontinent- und Klimazyklen, heute nicht mehr beobachtbare Evolutionsprozesse und Ereignisse wie die „Kambrische Explosion“ und den Landgang der Vielzeller eingehen. Bei der Veranschaulichung hilft das Vorhandensein von Originalen, die man aus der Nähe ansehen, unter das Mikroskop legen und gelegentlich auch berühren kann. Zudem ist man am Museum nicht dazu gezwungen, Schulkindern abprüfbares Wissen zu vermitteln, sondern kann (z.B. zum Ursprung der Schildkröten und des Schildkrötenpanzers) widersprechende Lehrmeinungen aufzeigen. Im Zweifelsfall sollten Kinder auch dann schöne Erinnerungen aus dem Museum mitnehmen, wenn sie mal keine Lehrinhalte aufnehmen konnten oder wollten. Diese positive Erfahrung versuchen wir am Museum für Naturkunde Magdeburg z.B. im Rahmen von Ferienprogrammen und Projekttagen durch Objekte zum Selbstanfertigen und Mitnehmen zu unterstützen. Dazu gehören u.a. Abgüsse von Fossilien unterschiedlicher, aber verwandter Formen (wie Kopffüßer-Gehäuse, Saurier-Fußspuren und Saurierkrallen) zum Selbstkolorieren; Miniatur-Dinosauriernester, bestehend aus gruppenspezifischer Nistmulde, Eiern und Sauriermodell (z.B. als Osterferien-Thema); das selbst gebastelte Miniaturmuseum zum Bestücken mit eigenen Exponaten; Linolschnitt-Drucke und Schablonen-Bilder zum Thema Großsäuger der Eiszeit und Höhlenmalerei; Daumenkino und Popup-Bild zum Thema Saurierspuren und Fortbewegung. Diese Beispiele werden auch beim Public-Outreach-Event der Geo4Göttingen vorgestellt.

An integrated outreach initiative focusing on the South Tyrolean Supervolcano successfully increased public awareness of one of Earth’s largest and least known volcanic systems, especially among younger audiences. Combining geological research from the “Living with the Supervolcano” and “Caldera” research projects with creative educational strategies, we developed Caldera – Spurensuche im Supervulkan, an interactive exhibition showcasing the dynamic relationship between the ancient volcano and its surrounding ecosystems. This exhibition later evolved into a travelling format, incorporating themes of sustainability to further enhance its educational reach and expanded to include school workshops and interactive programming. A series of short videos exploring the supervolcano, the exhibition process, and fossil research techniques broadened the outreach. Artistic collaborations—such as Forest Futurism and 6_VOCI—offered further ways to explore geological narratives through creative expression. As a lasting outcome a children’s book blended storytelling with nine geologically themed excursions to inspire families to explore the region through a scientific lens. Our initiative demonstrates how interdisciplinary collaboration can transform complex geoscientific topics into accessible, meaningful, and memorable public experiences.

During a palaeontological excavation in the Thuringian Forest near the town of Oberhof (Free State of Thuringia, Central Germany), a fragment of a xenacanthid shark skeleton was recovered. The new fossil finding belongs stratigraphically to the Lower Protriton-Horizon of the Lower Oberhof Formation (Lower Rotliegend, early Permian) in the Thuringian Forest Basin. This xenacanthid is preserved on a grey coloured, lacustrine siltstone that measures 7 cm in length and 13 cm in height; a smaller counterpart of the rock slab is preserved as well. The brown coloured remnants of the xenacanthid skeleton include hemal, neural, basal spinae, dorsal radialia, parts of the pelvic fin, and modified scales of the lateral line organ. Compared to literature, lateral lines appear to be rarely preserved in xenacanthid fossils.

In southwestern Kyrgyzstan, a complexly folded landscape provides an exceptional opportunity to study geological and biological evolution throughout the Phanerozoic in a one-day walk. Situated between the Southern Tian Shan and the Fergana Basin, the Madygen region offers an almost continuous stratigraphic record from the Cambrian to the present. While the Paleozoic and Cenozoic sequences are predominantly marine, the Mesozoic strata reflect extended continental environments.

To promote scientific research, education, and geotourism in this developing country, the Madygen area aspires to become a certified UNESCO Global Geopark. Madygen’s great potential for paleobiological research also offers an ideal setting for science communication. A new series of paleoart brings to life the diverse fossil flora and fauna, as well as the manifold habitats across the Phanerozoic.

The local Madygen Formation, a lacustrine Middle to Late Triassic fossil conservation Lagerstätte, impresses with its exceptional quality and quantity of paleontological finds. To date, over 30,000 fossils—including at least 500 insect species, twelve endemic vertebrate species, and numerous ichnofossils—have been recovered from these strata (Voigt et al., 2017).

But Madygen’s geological and paleontological richness extends far beyond the Triassic. The area’s diverse Cambrian fauna includes stem-group cnidarians and mollusks, brachiopods and trilobites, and many newly described taxa (Geyer et al., 2015). Prominently red Cretaceous strata with large ichnofossils transition into Paleogene marine sediments, which represent unique paleogeographic realms containing oysters and other mollusks, chondrichthyan and fish fossils, and various microfossils (e.g., Trubin et al., 2025).

The umbrella organisation for the geosciences DVGeo has been organising the German Geoscience Olympiad for school pupils since 2023.

This nationwide competition builds on school knowledge from geography as well as chemistry, physics and biology and provides deeper insights into the geosciences. Students from year 9 to Q1 (qualification year 1 for the Abitur) can take part, i.e. up to and including year 11 for G8 and year 12 for G9. The German Geosciences Olympiad was conceived by representatives of the DVGeo's supporting organisations from the fields of geology, geophysics, palaeontology and mineralogy.

The German Earth Science Olympiad is also the national selection competition for the established International Earth Science Olympiad (IESO), which will take place in China in 2024 and 2025. Participants have to demonstrate their knowledge of geology, mineralogy, geophysics and geochemistry in an online test. In the second round, they also completed practical tasks, including rock speeches.

The aim of the competition is to arouse pupils' interest in the geosciences and to make teachers aware of the geoscientific content of current topics. To this end, it uses the name of an Olympiad, which is commonly used in Germany for science competitions (see also Maths Olympiad). The tasks are predominantly competence-orientated.

The results achieved show a clear connection between the geoscientific content anchored in the curricula of the federal states and the results of the Olympiad.

This project presents the design, implementation, and evaluation of an educational museum tour titled “Minecraft vs. Reality – Rocks, Minerals, Ores, and the Use of Natural Resources”, developed for fifth-grade students at Bavarian secondary schools.

Geoscientific topics such as rocks, minerals, and natural resources are essential for understanding sustainability but are only briefly covered in early secondary education. This tour addresses that curricular gap through science communication in an informal learning environment. By drawing on the pop culture phenomenon Minecraft, it connects digital experiences with real-world geoscience, using the game’s popularity to spark curiosity and engagement.

The tour follows a learning-at-stations format, consisting of four hands-on stations where students explore minerals, rocks, ores, and their uses through original specimens, interactive tasks, and guided comparisons with the game's representations. Gamification elements support motivation and long-term learning.

To evaluate the program’s educational effectiveness, pre- and post-questionnaires were conducted with participating school classes. The study investigates students’ prior knowledge, misconceptions, and learning gains, while addressing research questions around motivation, conceptual understanding, and the corrective potential of informal learning experiences linked to digital media.

Although originally designed for school groups, the tour is adaptable for broader audiences during public events such as a family activity day. With minor adjustments, the format holds strong potential for outreach beyond the classroom and across different age groups, positioning the museum as an accessible and engaging site of geoscience education.

Relying on geophysics, mapping technique, spectral analysis, topographical, geomorphology, climate data, weather forecast and environmental analytical method to determine aquifers, water storage,structural geology, regional geology, sedimentology and ground water flow models which can be applied to create useful maps to generate information as requested.

Leafy liverworts (Marchantiophyta: Jungermanniidae) are important components of extant ecosystems, for example in peatlands of the northern hemisphere and in tropical forests where they constitute a large part of the epiphytic biomass. While the early evolution of this diverse lineage remains obscured by its sparse Paleozoic and early Mesozoic fossil record, amber inclusions found since the mid-Cretaceous have provided significant insights into its diversification. To date, ten amber deposits have yielded leafy liverwort inclusions, with the most diverse floras preserved in Cenozoic deposits. Amber fossils have been described from the mid-Cretaceous of Myanmar (Kachin) and Alaska, the Paleogene of India (Cambay), the Baltic region, Germany (Bitterfeld), and Ukraine (Rovno) as well as the Miocene of Ethiopia, China (Zhangpu), the Dominican Republic, and Mexico (Chiapas). The life-like, three-dimensionally preserved amber fossils reveal minute morphological details critical for identifying leafy liverworts and therefore allow for a reliable classification. The fossil evidence also provides age constraints for molecular phylogenies of extant taxa. The resulting divergence time estimates and diversification analyses indicate that — while many lineages probably predate the Permian-Triassic boundary — most extant genera originated during the Cretaceous or Cenozoic, coinciding with the rise of angiosperms. The profound changes of terrestrial ecosystems during the Angiosperm-Terrestrial-Revolution seem to have largely affected the epiphytes which exhibit a steep increase in lineage diversification, while generalists or largely terrestrial taxa were not affected.

As natural hazards, landslides cause significant economic and societal damage. In the context of climate change, both frequency and intensity of extreme rainfall events as key triggers of landslide are expected to increase. Due to its high local relief and the highest elevations within the German Central Uplands, the Black Forest is repeatedly affected by landslides. In order to a better assess the likelihood and impacts of future landslides, it is crucial to identify and analyze the triggers, spatial distribution and development of paleolandslides.

However, so far there is little knowledge about the occurrence and spatial extent, not to speak of age distributions of landslides in the Black Forest. Preliminary data suggest that the current geological and hazard maps provide an incomplete and imprecise representation of landslides in the Feldberg area. This implies that many more landslides may exist across the Black Forest than previously assumed, highlighting the need for improved mapping and analysis of past events.

The research project includes a GIS-based approach combined with detailed geomorphological field mapping for the development of a landslide inventory, as well as Terrestrial Cosmogenic Nuclide Dating and Schmidt-Hammer Exposure Dating for the age determination of paleolandslides. Two study areas are selected for cluster and trigger analysis, characterized by contrasting lithological settings and varying degrees of glacial influence.

Today, the insect group Dictyoptera includes cockroaches, termites and praying mantises with an almost worldwide distribution. The evolutionary origin of the ingroups is still debated, but there is no doubt that cockroach-like representatives of Dictyoptera (sensu lato) or ‘roachoids’ were already abundant in the Carboniferous more than 300 million years ago.

A special feature of extant species within Dictyoptera is their ability to form a special egg case, the so-called ootheca. According to current knowledge, this characteristic was probably not shown by Carboniferous early roachoids due to the morphology of their egg-laying structures. The first direct evidence of oothecae can be found in fossils from the Cretaceous in amber and limestone. Since this time, cockroaches have developed various strategies with regard to oothecae: Some groups simply drop their oothecae after producing them or carrying them for a while (oviparity), other groups keep the oothecae in a brood pouch just before the nymphs hatch (ovoviviparity), or even longer (viviparity). However, the evolution of these strategies is largely unknown, and oothecae are surprisingly rare in the fossil record.

We present different cases of fossil oothecae in amber and limestone from the Cretaceous, Eocene and Miocene. We discuss different types of oothecae and indications for their mode of oviposition. With these new finds we can provide further information for the evolutionary reconstruction of the reproductive strategies of Dictyoptera in the deep time.

Extant insects are adapted to a wide range of habitats and lifestyles on account of numerous specific strategies. In addition to foraging, defence and camouflage, reproduction is one of the existential determinants. Within insects, not only mating strategies are diverse in order to increase the chances of survival of the offspring, but also all aspects regarding the egg: the production of eggs, morphology and laying behaviour.

The number of eggs in a clutch, their size, shape and surface structure as well as the placement of the egg and the parental care after laying are often very characteristic of certain insect groups or species. However, when an isolated egg or clutch is observed, it can be difficult to identify the specific producer, even in extant insects because necessary information is missing in the literature.

The identification of the producer of a fossilised egg is even more difficult, which is further aggravated by the fact that insect eggs are rarely found in the fossil record in general and in amber in particular. The reasons for the rarity of eggs lie in taphonomic aspects, which depend, among other things, on the delicacy of the eggs and hidden deposits under bark or under the ground that were inaccessible to resin.

We present insect eggs and clutches preserved in amber from the Cretaceous to the Miocene and discuss aspects of the evolution of egg production, egg laying and egg morphology strategies. We also illustrate how knowledge about fossil eggs in amber can be expanded.

Besides the Early Permian Fossil Forest, for which Chemnitz is known in the palaeontological literature worldwide, temporary outcrops in the north of the city have yielded a rich fauna and flora from the late Early Carboniferous. 19th- and early 20th-century sandpits and a motorway construction site in the early 2000s allowed for insights into the Ortelsdorf and Berthelsdorf Formations of the Hainichen basin (330 ± 4 Ma for the upper Ortelsdorf Fm). Characterised by loose sandstones, thin coal seams, carbonatic siltstones and locally thick conglomerates with large boulders, these formations document frequent changes of braided-river, swamp and alluvial plain conditions. The sandstones preserve a diverse flora consisting of mosses, horsetails, ferns, seedferns, and lycophytes, a terrestrial arthropod assemblage comprising myriapods, trigonotarbid and phalangiotarbid arachnids, scorpions, and Arthropleura, aquatic arthropods and vertebrates including chondrichthyans, possible actinopterygians, sarcopterygians, and Germany‘s oldest tetrapod. Most remarkably, the chondrichthyan record involves two types of shark egg capsules – Fayolia sterzeliana and Palaeoxyris sp. – which in places occur on the same bedding plane, and a xenacanth cephalic spine that probably derives from the producer of the Fayolia capsule. No further remains belonging to xenacanths or hybodonts correlative with the Palaeoxyris capsules have been found so far. Nonetheless, the Chemnitz locality represents the oldest record of chondrichthyan egg capsules worldwide and the only site where two types of capsules not only co-occur in the section, but actually are found on the same surface, indicating nearly synchronous deposition by two different groups of producers in the vegetated nearshore area.

Sedimentary rocks are rare in Iceland's predominantly magmatic landscape. We analyse a sedimentary rock from NW Iceland that exhibits remarkable behaviour: it releases large amounts of gas while immediately decomposing upon contact with water. The sample is brown, fine-grained, and has a low density. At high microscopic magnification, a planar texture is visible. Previous analysis concluded that the rock is x-ray amorphous and does not contain swelling clay minerals that would explain its behaviour.

New XRD analysis reveals that the material consists to 70 wt. % of illite and to 20 % wt. of illite-smecite mixed layer. In addition, it contains goethite, quartz, and, as confirmed by infrared (FTIR) analysis, organic material. These results are complemented and supported by Inductively coupled plasma mass spectrometry and scanning electron microscope analysis.

µCT measurements show no significant pore volume above 1 µm. Most likely, the gas is not only trapped in pore space between the clay particles, but also in the interlayers of the interstratified phases (illite-smectite). One of two independent analyses of the gas released during decomposition shows significantly elevated CO₂ concentrations compared with air and we identified organic molecules that hint to oil and plants.

To understand if the extraordinarily rapid decomposition can be solely attributed to the clay content, we investigate further using a wide range of analytical methods, e.g., porosimetry measurements and surface area determination by gas adsorption. We also aim to gain inside into the geothermal history and organic petrography of the rock by applying a Rock-Eval pyrolysis.

Fossiliferous tree resin, known as amber resin, is a unique material that offers the rare opportunity to observe organisms from deep time, sometimes preserved in exceptional quality. Thanks to the quick encapsulation of the animals, it facilitates the unique preservation of past ecological interactions, offering a glimpse into how past ecosystems looked like up to 100 million years ago. We here investigated a syninclusion preserved in Eocene Baltic amber (~40 mya) in which two astigmatan mite specimens and a bristly millipede were fossilised in close proximity. The two mites are identified to be adult representatives of Glaesacarus rhombeus, one of them female. This is a species of mites that is frequently found in Baltic and Rovno amber, considered to be now extinct. The bristly millipede is also a female adult, identified as a representative of Polyxenus, exhibiting remarkable morphological similarities to the extant species Polyxenus lagurus; indicating that they have probably been thriving since the Eocene. This syninclusion provides an interesting interaction, with one of the mites seemingly surrounded by the defensive setae of the millipede, but it also provides clues on the shared microhabitat of these two groups in Eocene forests. The striking persistence of morphological traits in representatives of Polyxenus over 40 million years suggests a stable ecological niche and effective adaptive strategies, highlighting the evolutionary stability, resilience, and long-term success of the group. Although the two lineages here represented used to share the same habitat in deep time, despite being commonly entrapped, they displayed different evolutionary trajectories.

Reports of beetle larvae in amber are relatively rare, compared to the size of the group Coleoptera. Yet, to understand an ecosystem such larvae are quite important, due to their long interaction time with the environment, their enormous biomass, and their highly diverse morphologies coupled to myriads of ecological functions. We here report 16 new fossil beetle larvae of Elateridae, the group of click beetles, preserved in Cretaceous Kachin amber (Myanmar/Burma). The morphology of the new specimens stands out by the head having a prominent fronto-clypeus dorsally and the mouthparts forming a special maxillo-labial complex. The posterior end of the specimens bears paired projections and a prominent anal opening ventrally. The morphology of the larvae, especially of the toothed sickle-shaped mandibles, indicates a predatory lifestyle. We performed a quantitative comparison of the newly reported fossil beetle larvae and fossil and extant lacewing larvae using a shape analysis. The latter seem to have occurred in the same habitat and both appear to have been predatory. The lacewing larvae seem to have been quite dominating, possibly competing with the beetle larvae for resources. Our results indicate a morphological and also ecological differentiation between the two groups. This outcome shows how functions in a shared habitat can differ in animals of similar size. Furthermore, we discuss the functional aspects of mandibles and stylets (special mouthparts of lacewings) and compare them between the new fossil beetle larvae and the fossil larvae of lacewings.

Research on sea urchins from the Rhenish Massif began in the 19^th and early 20^th century with description of several species from the Middle Devonian of the Eifel synclines. While some of the type specimens were stored in collections in Germany, others were eventually sold to the US. During World War II, several important specimens in the collections in Göttingen and Munich were destroyed, and with the German partition after the war, specimens stored in East Berlin became inaccessible to researchers from West Germany. Subsequently, when West German researchers J. Haffer and S. Jentsch attempted to revise the genus Lepidocentrus, they were limited by the lack of available material and synonymized the species L. lenneanus, whose type material had been lost, with L. muelleri, and assigned a newly found specimen from the Sauerland to L. rhenanus, whose holotype was unavailable to them. Current re-investigation by the authors shows that L. lenneanus and L. muelleri are distinct, and the assignment of the Sauerland specimen to L. rhenanus is a mistake that resulted in researchers overlooking that L. rhenanus and L. muelleri may be conspecific. Another species from the Sauerland was described by East German researcher H. Nestler in 1982 as Palaechinus praematurus and placed in the family Palaechinidae, which is confirmed by newly found material. This species is very significant, proving a pre-Carboniferous origin of the family, but surprisingly, Nestler’s work was never recognized or cited by later authors, presumably because it was simply unknown to other researchers.

Geoparks are an important link between science and the public. In the guise of geotourism, they not only strengthen sustainable regional development, but also offer an interesting encounters with geology and the profound history of our planet. Geoparks enable universal access to the earth as a habitat and thus strengthen respect for nature in society.

The concept of Geoparks is designed to captivate, interest and educate people from different backgrounds. From an early age, visitors can immerse themselves in the history of the earth in a playful way with information boards, information points and games. Geoparks also offer a wide range of activities for adults: numerous geosites, guided tours, themed cycling and hiking trails and more, deepen the understanding of the environment and geology among interested locals and tourists. In this context, the Geoparks also play a decisive role, as they maintain, protect and preserve the geological heritage in the spirit of international research with their regional network.

In addition to its status as an extracurricular educational site, the Geopark Ries educational network for example enables "Geopark Ries Schools" to implement projects directly in exchange with teachers and pupils. There are teaching materials on the Ries event, projects for the preservation of intangible cultural heritage and a series of events “From science to the classroom” in cooperation with universities.

Geoparks therefore play an important role in raising public awareness of the relationship between geology, nature and people, thereby laying a solid foundation for a sustainable future.

Despite distinct evolutionary origins, the gastropod Araeodactylus and Perissoptera lineages show striking morphological parallels, suggesting convergence in ecological roles and locomotion strategies after the K-Pg boundary.

Araeodactylus, known from Paleogene strata, likely originated in the Late Cretaceous and is linked to “Chenopus buchii” Münster, 1839 sensu lato, with a possible Jurassic ancestor in Bicorempterus Gründel, 2001. Key morphological features include a teleoconch with spiral lines, a single apertural digit, and a straight to slightly bent rostrum.

On the other hand, Perissoptera likely descends from the Jurassic Pietteia Cossmann, 1904, both characterized by axial teleoconch ornamentation and a similar single apertural digit, which evolved in Perissoptera into a wing-like structure by the Maastrichtian.

Post-K-Pg, both lineages developed broad wing-like extensions. These may have functioned as protective feeding chambers, as in Xenophoridae, or supported locomotion—hydrodynamic gliding or swimming—as proposed by Savazzi, 1991, aligning with the diverse movement strategies seen generally in Stromboidea. While the Araeodactylus group and the broad-winged members of the Perissoptera group fully vanished in the Paleogene, various genera of the Perissoptera group survived and are now known as the family Rostellariidae.

Conclusion:
Despite originating separately, Araeodactylus and Perissoptera lineages demonstrate strikingly parallel evolutionary stories shaped by mass extinction at the K-Pg boundary, adaptive radiation, and eventual climate-induced collapse in the Oligocene.

Reference:

Savazzi, E. (1991). Constructional morphology of strombid gastropods. Lethaia 24(3): 311-331.