A pilot plant for an aquifer thermal energy storage (ATES) system in a contaminated aquifer is under construction at the scientific park of Leipzig. The research at this pilot plant is focused on developing and testing technologies to simultaneously store energy from shallow aquifers through an ATES system and remediate the contaminated aquifer.

For this purpose, investigations will be conducted in an approximately 10-meter-deep sandy/gravelly aquifer which is contaminated with chlorinated volatile organic compounds (Cl-VOCs). The main contaminants are trichloroethene (TCE, up to 6.0 mg/l) and cis-dichloroethene (cis-DCE, up to 0.4 mg/l).

With a two-well system that runs cyclically, the proposed ATES system will inject up to 80 °C heated water. This has a greater impact on the chemical composition of the groundwater than ATES systems that operate at lower temperatures. A previous field project revealed a considerable change in hydrogeochemistry and the microbiological community at temperatures of 45 °C and 60 °C.

As a result, this study investigates the hydrochemical and biological interactions that occur in the extraction and injection wells, the thermally affected aquifer as well as in the aboveground system. Cl-VOCs will be removed from groundwater using an on-site regenerable zeolite absorber (Fe-zeolite) and in situ degradation with persulphate.

Furthermore, these investigations will be supported by stable isotope biochemical and abiotic migration investigations of Cl-VOCs as well as microbiological and geochemical analyses including trace elements. It is anticipated to enhance the carbon footprint of urban energy management by the ATES operation, including groundwater remediation.

Within the KONATES project, an Aquifer Thermal Energy Storage (ATES) system is planned in the scientific park of Leipzig, where the groundwater is contaminated with chlorinated volatile organic compounds (Cl-VOCs). Supported by the SpeicherCity project, corresponding numerical model is being further developed and applied to study the environmental impact of ATES operation.

From the regulatory perspective, the operation of ATES system in the urban area should not induce temperature changes beyond a few degrees Celsius at the boundary of the properties. The challenge faced in the KONATES project is that this temperature limit will be quickly exceeded, as the injection temperature is planned to be ca. 80°C. This requires a careful planning on the timing, duration, and location of the injection, as well as the pumping rate.

To satisfy the regulatory requirements and facilitate the understanding of such impacts, a 3D numerical model has been constructed, simulating both hydraulic and heat transport process in the aquifer. The model is capable of predicting the propagation of the thermal plume in response to different design of injection temperature and flow rate. Due to the high groundwater velocity, it shows that at a pumping rate of 600 l/h, injection can only be carried out for 12 days continuously without increasing the groundwater temperature more than 2°C at the boundary.

The next step of model development is to include feature that reflects the elevated mobility of the Cl-VOCs, which is relevant to the quantification of extracted contamination in the surface treatment facility.

Aquifer Thermal Energy Storage (ATES) is a highly promising technology for storing excess energy due to its high storage capacity and small surface footprint. Despite its numerous advantages, planning, approval, and application are not yet widespread in Germany. Mineral precipitation and biofilm formation can lead to clogging of wells and aquifers. In addition, changes in the physico-chemical conditions may trigger the mobilization of toxic trace elements such as arsenic. The BMBF-funded joint project UnClog-ATES aims to investigate biogeochemical processes in the subsurface that may reduce the efficiency and long-term performance of ATES systems.

Sterile and non-sterile flow-through experiments are conducted under anoxic conditions, using both siliciclastic sediments and groundwater from a potentially ATES-suitable saline aquifer in Berlin. Through laboratory studies, the project investigates the effects of temperature changes, variations, and temporary oxygen input, and analyzes changes in the chemistry, mineralogy, and microbial community of both the groundwater and aquifer. Numerical models, including reactive transport and batch models, are developed using PHREEQC. Sensitivity analyses aid in the calibration and validation of models. They provide valuable insights into the geochemical behavior of the aquifer system and its response to different scenarios or conditions, by identifying the most influential parameters. Another key objective is to determine biogeochemical indicators that can be used to forecast clogging and define practical countermeasures to prevent or mitigate adverse effects in the aquifer.

Here we present our experimental setup and first modeling results for an ATES-suitable formation located in Berlin, Germany.

Microbial processes such as biofilm formation (clogging) and mineral precipitation (scaling) can affect the effectiveness of ATES systems. They can reduce the permeability of potential reservoirs and compromise the efficiency of ATES facilities on the long term. In addition, microbial processes can influence dynamics of toxic trace elements in the subsurface e.g. by releasing arsenic through iron mineral dissolution. Hence, it is crucial to identify microbial key players and metabolic processes to estimate the microbial impact on ATES and the clogging potential.

Here, we analyze the microbial abundance, community composition and their functional potential in relation to the thermo-hydrogeochemical conditions of bulk sediment and formation water of a Mesozoic sandstone aquifer of the North German Basin. The study focusses on the application of DNA-based approaches such as qPCR, high throughput sequencing and metagenomics. Bulk sediments and fluids were obtained from Jurassic sandstone in Berlin, Adlershof from a depth of 200-450 m.

The aquifer is characterized by an in-situ temperature of 17-22°C, Na and Cl dominated fluids (TDS ~20 g L^-1) and DOC including acetate (~3.5 mg L^-1), propionate and valerate. First results show that the fluid microbial community is adapted to saline and alkaline conditions. The community is highly dominated by the two taxa Alkaliflexus and Defluviitaleaceae UCG-011, but also contains sulfate reducing bacteria.

Results of this study together with a flow-through experiment analyzing geochemical, hydrochemical, mineralogical and microbiological processes under different conditions typical for ATES, will help to develop prediction tools for potential system operational failures and appropriate countermeasures.

The energy concept for the VW library in Berlin, which was built in 2004, centers on a ground foundation absorber (GFA) that uses concrete core temperature control to freely cool the building in the summer and cover the building's base heating load in the winter via a heat pump. Due to unexpectedly high subsurface temperatures beneath the building, as well as difficulties in controlling the concrete core temperature control system, the GFA has been largely decommissioned in recent years. The goal of this research is to work with building engineers and engineering geologists to determine the cause of the elevated temperatures and to transition the GFA to optimized seasonal operation. To this end, detailed thermal models were created for the building and the subsurface, validated with measured data, and coupling approaches between the models were investigated. This should ensure a better evaluation of the interaction between the subsurface and the building during operation. Model-based parameter studies will then be used to determine an optimally adjusted operation of the GFA. In addition, the temperature development of the subsurface of the study area will be investigated to ensure sustainable operation. Optimized reactivation of the GFA shows significant ecological and economic potential with annual savings of 15% of the building's CO₂ emissions and €23,000 in energy costs compared to the current building operation. The developed adjustments to the operating and control parameters will be tested and monitored in the building during the coming heating periods.

The University Campus Charlottenburg/Berlin will be used as an example to show how geothermal energy can make a decisive contribution to a climate-neutral university campus. In combination with heat pumps, geothermal energy offers the possibility of a secure heat supply for the campus, which is in the process of transformation. The investigation addresses the geological horizons Muschelkalk and Buntsandstein at depths of 900 - 1250 m. Temperatures of 45 - 63°C and an extraction capacity of 1.2 to 4.7 MW are expected. Depending on the outside temperatures, direct use for heat supply can take place. The ongoing renovation process on campus significantly increases the direct use potential of geothermal energy. In the retrofitted state, the maximum supply temperature drops to 60°C with an outside temperature of -10°C. This demonstrates that the geothermal use of the underground can provide a reliable heat source for the transformation process on campus or in city quarters in general. An essential aspect of this utilization is the redesign of the heating network to allow a differentiated supply of buildings with different temperature levels. The example of the location's south campus shows that the use of geothermal energy enables a CO₂ savings potential of up to 64%. In addition, the use of geothermal energy for cooling supply via ad- and absorption chillers is investigated. This approach opens up new perspectives for the holistic use of geothermal energy and helps to increase efficiency and conserve resources in campus operations.

While the share of renewable energy in the electricity sector is steadily increasing, it has stagnated in the heat supply, despite the fact that in Berlin, for example, more than 40 % of the CO2 emissions are caused by the heating sector. Due to its ability to store large volumes in the underground while at the same time taking up little space on the surface, HT-ATES is particularly well suited for use in urban areas and can therefore contribute to the reduction of CO2 emissions. However, clogging of aquifer pores thus reducing the permeability, corrosion and mobilization of trace elements may be undesirable effects of HT-ATES.
Here, the Triassic limestones and the Jurassic sandstones were investigated as part of two Berlin ATES studies with the aim of (a) simulating the effect of HT-ATES operation on the carbonate aquifer by geochemical modelling, (b) identifying reactive mineral phases by systematic elemental analysis using a handheld XRF and (c) estimating the permeability and mobilization processes by column and batch experiments at elevated temperatures.
The results show that rapid analysis of drill cores at the drilling site provides important information on the presence of reactive mineral phases such as iron minerals, clay and carbonate content, and can therefore assist in filter placement. The mobilization of organic matter and trace elements has been observed in laboratory tests with siliciclastic sediments. The simulation of the HT-ATES operation in the saline carbonate aquifer, on the other hand, indicated carbonate precipitation due to temperature increase and degassing.

Sustainable development of enhanced geothermal systems (EGS) requires a comprehensive understanding of the in-situ stress conditions. Among several techniques developed in the last decades, Hydraulic Testing of Pre-existing Fractures (HTPF) is a common practice to quantify the normal stress acting on hydraulically isolated fractures. To better understand the hydromechanical coupled mechanisms involved during HTPF as well as validation of HTPF analysis methods, a decimeter-scale true triaxial testing (TTT) apparatus was utilized that allows HTPF measurements on fracture planes under anisotropic stress conditions.

This work is primarily focusing on the experimental setup, calibration, and boundary conditions of the TTT apparatus. The apparatus contains three sets of oil-filled flat-jacks, which independently control the stress boundary conditions in the (horizontal) x, y, and (vertical) z directions. Contained within a steel frame, the flat-jacks exert pressures onto loading plates, which transfer and distribute pressure onto the sample’s surfaces. The 30*30*45cm cuboidal granite sample contains a vertical saw cut fracture, oriented 45° in respect to the x and y axis. Boreholes, drilled through the sample to the fracture surface, allow high-pressure fluid injection and monitoring of the fracture fluid pressure. Thirty-two acoustic emission sensors, mounted in the loading plates, allow for active and passive seismic measurement. The deformation of the rock sample is captured by 16 linear variable differential transformer (LVDT) displacement sensors mounted externally to the loading plates. The test procedure and preliminary results of the HTPF tests can be found in Osten et al. (2023; this conference).

The deep geothermal reservoir potential in North Rhine-Westphalia was assessed in Devonian carbonates (Massenkalk) in the Steltenberg Quarry in Western Germany. The karstification phenomena of the carbonates were recorded utilising drone images in the quarry. Rocks at the karst chutes were examined by polarisation- and cathodoluminescence microscopy regarding karstification phenomena and carbonate cements. X-ray diffraction and inductively coupled plasma analyses were carried out to gain mineralogical information about different carbonate phases in various samples. Carbon and oxygen isotopes were analysed to understand the formation conditions of the carbonates. The examined rocks at the karstification structures show that the host rock (Massenkalk) has average marine δ¹³C_mean values of 3.7 ‰ VPDB and -4.7 ‰ VPDB for δ¹⁸O_mean. At the karstification surfaces and leaching zones, the isotope analyses revealed values of meteoric overprinting in the form of increasingly more negative δ¹³C values down to -8.5 ‰ VPDB and -5.9 ‰ VPDB for δ¹⁸O. These changes in the formation conditions are strengthened by cathodoluminescence results. The narrowing of karstification observed by drone with increasing depth in the quarry walls and the siliciclastic sediments in these structures indicate near-surface karstification. These dissolution structures have presumably developed in cracks caused by tectonism. It can be assumed that karstification at greater depths is also possible due to fault associations, which could be caused not only by meteoric waters but deep hydrothermal CO2-bearing fluids

Deep geothermal power plants are baseload-capable and can serve as substitutes for fossil fuel power plants. In the Ruhr region of Germany, a densely populated area with high energy demand, potential deep geothermal reservoirs have been limited to a few sedimentary layers, specifically Carboniferous and Devonian strata. These reservoirs have not been explored with hydraulic field studies for geothermal purposes so far. Deep boreholes for geothermal research are non-existent, so shallow boreholes provide an analogue for evaluating the potential of deep reservoirs.

For this study, a naturally-fractured Carboniferous sandstone and a karstic dolomitic limestone reservoir of the Devonian were investigated using geophysical borehole measurements, hydraulic and hydrochemical experiments, and acoustic/optical televiewer recordings.

The sandstone formation (investigated depth: 20 – 305 m) showed a low hydraulic conductivity, and it is probably necessary to drill into fault zones or to enhance the permeability via stimulation in future geothermal projects. Chemical enhancement of permeability was attempted using CO₂ to dissolve carbonate fillings in fractures, but further research is needed to evaluate the effectiveness of this method.

The dolomitic limestone formation (investigated depth: 10 – 224 m) exhibits exceptional permeability due to enlarged fractures, cavities and vuggy porosity resulting from karstic processes, making it a promising reservoir overall. However, further confirmation is required at reservoir depths (e.g. 2500 – 4000 m).

In summary, deeper geothermal reservoirs in the Ruhr region have not been explored enough so far, and further field studies are necessary to evaluate their potential for geothermal energy production.

Groundwater temperatures (GWTs) vary based on the local geothermal heat flux, the energy budget at the surface, and land cover. With subsurface temperature data being scarce, standard techniques for the spatial interpolation often produce unrealistic representation of shallow GWT. It has been shown that utilizing remote sensing data can reproduce shallow GWT at an error of roughly 1 K. In our contribution, we apply such a technique to the state of Saxony-Anhalt, Germany. The estimation is trained and validated with a set of over 600 observation wells. The data used comprises data from the Landesbetrieb für Hochwasserschutz und Wasserwirtschaft Sachsen-Anhalt (LHW) as well as own monitoring campaigns for the cities of Magdeburg, Halle (Saale), and Dessau. Together with different satellite datasets, such as land surface temperature and building density, we use this measured GWT data to derive spatially resolved estimated GWTs (eGWT) for Saxony-Anhalt. The measured and estimated GWTs are then correlated to the land cover at the location. Thus, this study aims to (1) present measured GWT and eGWT distribution for Saxony-Anhalt, (2) assess the application of satellite data for estimating shallow GWT, and (3) research the correlation between GWT/eGWT and land cover.

To extract heat from tight deep subsurface formations, hydraulic stimulation is used to create efficient heat exchangers in the context of enhanced geothermal systems (EGS). Successful geothermal reservoir initiation requires detailed characterization of the regional in-situ stress field and local stress field variations of heterogeneous, i.e. fractured and faulted rock masses, which is often achieved by hydraulic fracturing (HT) and hydraulic testing of pre-existing fractures (HTPF).

To further develop and validate these field-scale in-situ stress determination techniques, decimeter laboratory scale HTPF tests into saw-cut and polished fracture planes are performed in a true triaxial testing apparatus (see Cadmus et al. 2023, this conference for details). Tests are carried out under various anisotropic stress boundary conditions to analyze normal opening and shear behavior. Results of two rock samples with different fracture roughness are analyzed and compared in terms of the injection pressure and flow rate evolution, shear displacement and acoustic emissions. The results indicate that both shear displacement and hydraulic jacking initiate as the injection pressure exceeds the fracture normal stress, which is attributed to heterogeneous fluid pressure distribution in the fracture plane. Future experiments on a fracture surface of intermediate roughness with additional observation boreholes aim to further assess the effects of fluid pressure distribution and fracture plane roughness in the context of stress measurement and induced seismicity.

Hydrothermal systems offer significant potential for green energy and heat production. The Buntsandstein Formations provide aquifers that are applicable for hydrothermal heat (or power) production. The Geological Survey of Brandenburg (LBGR) will improve its data base on Middle Buntsandstein aquifers using machine learning algorithms on archived exploration data.

Data stored in the archive of the LBGR contains drilling information for some 200 boreholes penetrating the Buntsandstein Subgroup. The LBGR has access to some thousand 2D seismic profiles from exploration surveys, typically reaching the Zechstein Group or the deeper-lying sandstone aquifers in the Upper Rotliegend Subgroups.

Drilling logs such as gamma ray or density logs provide valuable information for stratification and petrophysical rock property analysis. Available drilling logs will be digitized, and machine learning algorithms will be trained on exemplary data sets such as drilling E Hr 1/68. Machine learning algorithms will help to stratify the Buntsandstein sections of the available drillings. The stratification based on machine learning is further validated on newly interpreted seismic and drilling results, such as the cores stored at the drilling core and sample archive of the LBGR. The base will be in consideration of depositional gaps and tectonics. Also, a well-to-seismic-tie is performed at selected locations, and synthetic seismic profiles are generated.

If possible, seismic lines are (semi-)automatically evaluated to identify Hardegsen, Detfurth, and Volpriehausen Formations. Interpretation results are integrated in a 3D-geological model to build a regional-scaled Buntsandstein model of Brandenburg, allowing parameterization and calculation of reservoir temperature or heat in place.

The subsurface of the Aachen-Weisweiler area with its Carboniferous and Devonian carbonates is a green-field target location for testing and developing deep geothermal energy systems in North Rhine-Westphalia, Germany. Despite subsurface mining, surface mapping and isolated deep exploration wells and crustal seismic data, only sparse information on the deeper structures (down to 4,000 m), the spatial distribution of the reservoirs and reservoir properties has so far been recorded and/or published. Therefore, the complex structures of the faulted and folded Paleozoic layers remain unknown requiring further investigations. With the “Field Scale Laboratory for Deep Geothermal Energy Rhineland”, we aim to characterize the subsurface of the Aachen-Weisweiler area including its structural uncertainties, to quantify the reservoir properties of the carbonates and their associated parametric uncertainties to better describe the geological risk in exploring the reservoirs. Firstly, we constrain a geological model based on the publicly available surface and subsurface data and quantify its structural uncertainties. The model and the uncertainties are revised after the integration of vintage and newly acquired seismic data. Planned deep exploration wells will provide further constraints for the structural model but also deliver in-situ measurements of reservoir properties and geomechanical properties for subsequent thermo-hydraulic-mechanical modeling. The investigations contribute to the characterization of the potential geothermal reservoirs in this region, aid in the exploitation of the reservoirs, finding drilling locations for wells, and expand geological knowledge of the carbonates from other regions into Germany, hence, de-risking the geothermal plays in the Aachen-Weisweiler area.

The Opalinus Clay is the chosen host rock for the Swiss deep geological disposal of nuclear waste, and it is also investigated in Germany. For the long-term integrity of the disposal site, temporal and spatial stable geochemical conditions are essential. The identification of mineralogical and geochemical alterations in the Opalinus Clay and surrounding formations gives insights on their stability in the past, and thus enables an assessment for the future.

To detect the mobility of chemical elements and associated mineralogical changes, a 58 m long borehole was drilled at the Mont Terri Rock Laboratory (Switzerland). Drilling was conducted from the Opalinus Clay through the entire underlying Staffelegg Formation, which includes two water-bearing sections. The rock members and their transitions were characterised with a variety of analytical methods.

The results show that many trace elements are particularly enriched at the upper transitions of the water-bearing sections. At the top of the Rietheim Member (Posidonia Shale), this enrichment is accompanied by an increase in pyrite, which can be interpreted differently. On the one hand, the depositional conditions may have led to enhanced pyrite formation and the associated pyritization of trace metals. On the other hand, the overlying rock layers could have acted as cap rock for mobile elements in the pore water, leading to the observed accumulations. Consequently, to distinguish between depositional or diagenetic and alteration or mobilisation features is crucial for the interpretation of the analytical results in order to assess the long-term stability of Opalinus Clay and surrounding formations.

Geothermal systems in crystalline basement rocks require fractures and faults to allow economic heat production. Sufficient permeability of these flow paths is vital and affects the lifetime of such systems. As fluids are produced and reinjected, the resulting flow, fluid mixing as well as related pressure and temperature changes affect the geochemical equilibria between fluids and host rock. Disequilibria of fluids and rock then potentially drive geochemical alteration (e.g., dissolution, precipitation, illitisation). Such changes can affect the hydraulic properties of the major flow paths of the fault zones. Cornwall in SW England hosts several granitic plutons that are subject of current geothermal projects (United Downs Deep Geothermal Power and Eden Projects). These projects target fault zones in crystalline rock as pathways for fluid flow.

To study the effects of geochemical alterations on fracture permeability in granites, we conducted a series of long-term reactive transport experiments in our unique flow-through reactor setup. Carnmenellis granite samples from central Cornwall have been collected of which small, artificially fractured plugs (15 mm length, 10 mm width) and powders (< 125 μm grain size) were prepared. We injected water with different fluid composition, representing brines encountered around geothermal systems, into the fractured granite plugs and pulverized gouges at 80 °C and 20 MPa confining pressure. The development of sample permeability and effluent composition are analysed. CT-scans are used to analyse changes in fracture and gouge structure. To complement the experiments, we model our system with GeoChemFoam [Maes and Menke, 2021], an OpenFOAM-based reactive-transport modelling code.

Migration of neptunium, i.e. ²³⁷Np, a minor component of high-level nuclear waste, is in focus regarding the safety of nuclear waste disposal sites due to its long half-life and radiotoxicity. Opalinus Clay, the preferred host rock in Switzerland and also an option in Germany, is regarded as a reference formation with diffusion as the dominant transport process additionally retarded by sorption. One-dimensional diffusion simulations are conducted with PHREEQC to quantify neptunium migration. Sorption on clay minerals is integrated using surface complexation models. Numerical simulations are based on two diffusion experiments with the same setup, but one order of magnitude difference in transport parameters attributed to the core samples which stem from different rock facies. In the laboratory experiments, Np(V) was applied via a synthetic oxygen free pore water with neutral pH. The redox conditions are controlled by pyrite, while the pH of the system is buffered by calcite. The experiment of Fröhlich et al. (Radiochimca Acta, 2013, 101, 553-560) defined the numerical setup applied to the experiment of Wu et al. (Environmental Science & Technology, 2009, 43, 6567-6571). Our results indicate that neptunium migration is mainly controlled by pyrite oxidation and the associated reduction of Np(V) to Np(IV), while clay mineral quantities have only a minor impact. Since neptunium speciation and hence migration is very sensitive to oxidation and reduction reactions, redox conditions need to be accurately controlled and monitored in the laboratory if transport parameters are determined to be applied in the context of safety assessments.

The poster presents the framework of the modeling part of the BMWi-funded project "Li-Fluids" (grant number: 03EE4034A). It introduces PHREEQC modeling approaches for simulating lithium-bearing minerals in geothermal reservoirs. By integrating lithium sources into PHREEQC, the release of lithium can be simulated. Additionally, a 1D dual-porosity approach is used to define reservoirs and calculate time-dependent depletion.

However, there are challenges. The accurate calculation of brines requires the Pitzer approach, which is limited in the number of minerals considered and does not include aluminum. Li-Mica, a modified form of K-Mica, appears to be an important primary source of lithium in the host rock. To address these limitations, other databases like the SIT database can be extended to include lithium-bearing aluminum silicates.

Saturation experiments were conducted up to 200°C using pure H₂O, approximating the observed Li⁺ concentrations from gold capsule experiments conducted by the project partner BGR. These concentrations ranged from a few mg/l Li⁺. Since Al³⁺ is necessary for calculating the saturation indices of Li⁺-bearing aluminum silicates, the use of pure H₂O was necessary to combine the BGR's laboratory experiments with PHREEQC's capabilities.

The next step involves implementing reservoir properties and developing an approach for modeling transport using concentrated saline waters frequently encountered in deep sedimentary basins in Germany. Van Genuchten's (1985) approach, which incorporates dual porosity similar to sedimentary rocks, will be utilized in PHREEQC. This hydraulic extension, combined with deep saline waters (e.g., the North German Basin), facilitates the extrapolation of findings from pure water experiments to a quasi-reservoir.

In the context of the energy and mobility transition, operators of geothermal power plants and associated industries spotlight the potential to combine the production of sustainable energy with the extraction of strategic raw materials (SRM) (e.g., lithium) from geothermal fluids. Brine mining of SRM requires a comprehensive understanding of the related geothermal fluid system.

In southwest Germany, the Upper Rhine Graben (URG) represents a reservoir with great geothermal and SRM potential (thermal gradient up to 120°C/km; Li ~170mg/L). Data about the reservoir rocks and the thermal fluid at different depths is provided by ~1300 oil and geothermal wells as well as thermal water wells. Chemical data of sampled fluids indicate variations in the trace element distribution that are related to the Cl/Br-ratio, and trends of stable isotope systematics of the water.

The results show that in the northern URG evaporites are dissolved (Cl/Br>1200), while in the central URG the thermal waters have almost seawater composition (Cl/Br=290). Independent of the Cl/Br ratio, Li concentrations in the thermal waters vary between 3-43 mg/L. At nearly the same Cl/Br ratio of ~300 the geothermal fluids have ~170 mg/L Li. Stable isotope systematics imply that all thermal fluids have a meteoric component. The results indicate a modification of the fluid chemistry through time and depth, resulting from fluid mixing and water-rock interaction with various reservoir rocks. To investigate the fluid evolution, additional element tracers to determine the origin and raw material potential of Li and other trace elements, are established.

Petalite was the first mineral in which lithium was detected, but its economic importance is less than that of the lithium-rich spodumene. Both minerals occur in pegmatitic deposits (LCT pegmatites), which were explored in the past mainly for tin and tantalum. Nowadays, lithium-bearing minerals are the focus of mining. Although both minerals are similar in the processing and extraction of lithium, their mineralogical properties differ. Through roasting, petalite undergoes a phase transformation to β-spodumene, producing quartz as an excess. Subsequently, the roasted material can be fed into the established converter process to produce lithium hydroxide or lithium carbonate.

In order to cover the increasing demand for lithium for use in lithium-ion batteries as a contribution to the energy transition and the associated turn away from fossil fuels, investments in mining projects away from the particularly lucrative spodumene pegmatites are necessary. Petalite is one such alternative.

Using petalite deposits in Namibia as an example, we will show whether it is possible to determine the mine of origin based on mineralogical and geochemical properties to contribute to possible lithium fingerprinting as proof of origin. The approach is based on the combination of different analytical methods, such as EDX, electron microprobe and trace element distribution using ICP-MS. Lithium fingerprinting can then be used as a tool for material-based control of ESG criteria upstream in the lithium value chain.

Lithium is a critical raw material for the EU, being strategic for the energy transition, especially for battery production. Solutions are needed to reduce the EU dependency on the whole value chain and the geopolitical risks associated with the growing Li demand in a concentrated market. The deep geothermal reservoir in the Upper Rhine Graben (URG) along the German-French border not only show good conditions for direct energetic use but also high Li contents (160-200 mg/L). In this context, the deep geothermal reservoir has generally very similar geothermal and hydrochemical characteristics. An innovative lithium extraction process developed on Argentine brines by ERAMET and IFPEN was therefore installed directly on an extraction unit at the reinjection branch of an existing geothermal plant in the ORG. In the course of pilot-scale tests, the possibility of extracting lithium from geothermal brine was demonstrated in early 2021 in collaboration with Electricité de Strasbourg in the frame of the EUGELI project.
The extent to which lithium extraction can maximize the utilization of geothermal resources by combining lithium extraction with electricity and/or heat production via a single well will be shown in this poster presentation at an economic sensitivity assessment by evaluating the various key parameters and then subjecting them to a specific variation. Ultimately, this combined use of geothermal resources at an existing facility will demonstrate the extent to which environmental and social impacts can be avoided compared to conventional mining, or conventional brine lithium production.

The Hils Syncline is located in the south of the Lower Saxony Basin, Lower Cretaceous and Jurassic rocks crop out in its center. The Cretaceous and Jurassic sedimentary sequences in northern and southern Germany are known to be largely composed of clay-rich shales suitable for nuclear waste storage. Highly variable thermal maturity increasing towards the northwest characterizes the Hils Syncline, which makes it a natural laboratory to study the effects of burial and thermal maturation on petrophysical properties of shales at different levels of thermal maturation, which is our focus.

We reconstructed the burial and thermal history of the Hils Syncline resulting from a 3D-thermally-calibrated numerical model to better understand its geodynamic evolution, constrain maximum paleo-depths, –temperatures and erosion amounts, and evaluate their influence on the present-day petrophysical properties of Cretaceous and Jurassic units.

The basin experienced continuous subsidence interrupted by the Upper Cretaceous major phase of erosion. During the latest Early Cretaceous, deepest burial and maximum temperatures of Jurassic and Cretaceous rocks occurred showing an increasing northward trend. These units' porosity and vertical permeability decreased while the vertical thermal conductivity increased during burial. The Late Cretaceous inversion caused severe uplift and erosion that was stronger towards the northwest where up to 3,200 m of sediment was eroded compared to only about 1,200 m in the south. The petrophysical properties were not affected by the inversion according to the model. Calibration is currently performed based on new cores of Pliensbachian shales; thus, model results and experimental data will be compared.

In the context of the site selection procedure for a high-level radioactive waste repository in Germany, the fluid content in salt rocks is an important parameter to evaluate their barrier properties (i.e. gas formation potential and fluid pathways). Moreover, it can affect hydraulic conductivity, heat resistance, rock mechanical properties and it can be used for the spatial characterisation of the host rock. Fluids in rock salt (halite) are typically present in small, unconnected inclusions located within crystals or arranged along crystal boundaries and fissures, and can consist of brine, minor amounts of gases and hydrocarbons. When estimating the fluid content of rock salt, the main challenges are the low fluid content, the low permeability of the bulk rock preventing fluid extraction and the spatial heterogeneous fluid distribution. In summary, the measurements are time intensive and the results are highly dependent on the sample selection and preparation.

Nuclear magnetic relaxation (NMR) relaxometry is an established petrophysical method for a non-invasive characterisation of hydrocarbon host rocks and its fluids but it has not been used for rock salt so far. We present first results obtained from steeply inclined Zechstein rock salt (z2HS2) and compare them with a water content estimated by an extensive grinding of the salt samples in dried acetone and a subsequent analysis of the extracted fluids using infrared-spectroscopy. First results show, that NMR has promising features including a low limit of detection, non-destructive and quick measurements, no need for extensive sample preparations, and averaging over a large sample volume.

This study investigates sealing properties of Jurassic claystones, specifically Lias and Dogger mudstones of the Lower Saxony Basin, in the context of the disposal of high-level radioactive waste. Within the repository, the occurrence of various mechanisms such as corrosion, radiolysis, and microbial degradation may lead to generation of gases including hydrogen, methane and carbon dioxide. It has been reported through experimental studies that claystones possess hydraulic conductivities ranging from 10^-12 to 10^-15 m/s, indicating that the primary mechanism to dissipate the generated gases away from the repository is diffusive transport. Excessively high diffusion coefficients may compromise seal integrity, while overly low diffusion coefficients could result in localized overpressure zones, free gas formation, and interconnected gas transport pathways. Therefore, it is imperative to conduct a comprehensive investigation of gas diffusion in the context of nuclear waste disposal.

In the present study we assess the use of the pressure decay technique to measure gas diffusivity through water-saturated claystones. The experimental approach involved conducting radial gas diffusion into the pore space of core plugs that were sealed at both ends. Gas diffusivity was determined using a mathematical model that couples the analytical solution of the diffusion equation with the real gas law. Experiments were conducted on deionized water and water-saturated Boom Clay to determine hydrogen and methane diffusion coefficients, and the results are highly consistent with literature data obtained from other techniques. Currently, the measurement of hydrogen, carbon dioxide, and methane diffusion coefficients through water-saturated Lias and Dogger rock specimens is underway.

Middle Jurassic Opalinus Clay (OPA) is considered as host rock for the disposal of heat-generating high-level radioactive waste. For the present study, samples from the Mont Terri rock laboratory (Switzerland) were analyzed using sedimentological, mineralogical and geochemical methods. Thereby, the ordering of irregular illite-smectite interstratified clay minerals (I-S) was of particular interest as it is responsible for sorption of radionuclides and swelling properties.

Results support the classification of OPA into five main facies instead of the well-established threefold division, and further into six subfacies. The clay fraction present in the samples varies according to these facies, consistent with variations in cation exchange capacity. X-ray diffraction analyses of this < 2 µm fraction revealed a homogenous composition of the main constituents, namely R1-ordered I-S, illite and kaolinite. Crystal-structure based Rietveld refinement indicates strong similarities in the nature of disorder of the interstratified illite-smectite minerals. In all facies and subfacies the amount of illitic layers in the I-S varies from 73 - 85 % for all refinements and ordering types. Collectively, results point to (1) a homogenous overprint of the clay assemblage during burial and/or (2) a uniform siliciclastic sedimentary supply throughout the sedimentation period of the OPA.

This uniformity will facilitate the calibration of mineralogical models and the extrapolation of geophysical logging data where no data is available. However, the transferability of these calibrations to both other OPA locations and claystone formations should be critically examined.

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). In the report, BGE identified 90 individual sub-areas (in claystone, rock salt and crystalline rock), where favourable geological conditions for the safe disposal of high-level radioactive waste can be expected.

In Step 2 of Phase I, BGE aims to localise 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 characterisation and interpretation with focus on the host rock formation that acts as the main geological barrier, but also considers the surrounding rock formations.

This contribution describes some of the compulsory geoscientific interpretation steps (e.g. well log interpretation, subsurface modelling) that are required during the preliminary safety assessments, focusing on sub-areas with flat bedded rock salt. The assessment of the spatial geometry of potential barrier rocks as well as the interpretation of their internal configuration (e.g. facies) and the understanding of relevant geological processes affecting the safety of a potential repository site are important characteristics.

Rock salt is one of the three potential host rocks for the final repository for high-level radioactive waste in Germany. For the site selection procedure and for safety assessments, the content and composition of trapped fluids can be crucial to evaluate the potential of gas formation. Certain salt formations in northern Germany are known to contain gases and hydrocarbons as fluid inclusions. Fluid inclusion studies can provide information on their composition or temperature- and pressure conditions of fluid migration. Investigating individual fluid inclusion assemblages has certain advantages compared to bulk analyses: (1) the possibility to differentiate between different fluid sources and/or (2) the reconstruction of a complex fluid history. Among the suitable methods for the analyses of the fluid inclusion composition is Raman spectroscopy. Here we used a Renishaw inVia QONTOR Raman spectrometer attached to a Leica microscope (DM3000) equipped with a 100x objective and a 532 nm laser. Raman spectra were obtained with a 2400 grating, at ~5 mW, 180–240 s acquisition time and 2 accumulations in the spectral range of 300–4000 cm^-1. The analyses of the hydrocarbon phase show peaks at ~940, at 2500–2700 and 2900–3100 cm^-1 indicating C-H stretching modes, potentially of alkanes and their derivatives (Dollish et al., 1974; Orange et al. 1996).

The selection procedure to identify the site “best possible” to host Germany’s repository for the final disposal of its high activity nuclear waste considers claystone, rock salt and crystalline rock as potential host rocks. Preliminary considerations estimate the area required for a claystone-hosted repository to be 10 km². There are nine “sub-areas” (i. e. areas with conditions expected to be favourable for the safe final disposal of high activity nuclear waste) having claystone formations as potential host rock. Their sizes range between 943 and 62,885 km², which is roughly 90 to 6000 times the size considered necessary for a claystone-hosted repository. Consequently, reducing sub-area size sophisticatedly constitutes a major challenge to the site selection procedure.

The project SEPIA aims to apply a sequence stratigraphic approach to characterize and correlate barrier properties of Aalenian rock formations, namely the Opalinus Clay (OPA), in Southern Germany. Therefore, four drillcores constituting an approx. 330 km long transect have been acquired to derive the spatial distribution of clay-rich and -poor horizons across the sedimentary basin, eventually leading to a paleofacies map. In addition, correlation with results from similar investigations in Switzerland adds another 100 km to the transect. This will allow assessing to which degree results from the OPA characterization carried out in the Swiss site selection procedure can be transferred to Southern Germany. Overall, the approach used in SEPIA appears to be a promising one to identify potential siting regions of reasonable size out of the large sub-areas for detailed exploration.

The characterization of potential host rocks for the final disposal of high-level radioactive waste is of great importance in the site selection procedure. For clay-rich host rocks, hydraulic and geomechanical characteristics often depend on the burial history determining the maximum effective stress and temperature (i.e., maturity), and the associated compaction as well as transformations during diagenesis. Therefore, the direct transferability of host rock properties between different regional-geological sites is challenging and requires detailed quantitative knowledge about host rock property variations at different maturity levels.

We present the first results of the “Maturity” research project that deals with a Lower Jurassic clay rock via field and laboratory investigations. The target formation of Pliensbachian age (182–190 Ma) is located in the Lower Saxony Hils Syncline and the neighboring Sack Syncline. Whereas the mineralogical composition can be considered similar, the clay rock is characterized by a large thermal maturation gradient over a relatively short lateral distance. The project involves shallow core drillings at five locations along the sequence of changing maturities and an extensive testing program. We explore the influence of thermal maturity on the i) hydraulic rock mass properties using in-situ single-hole and cross-hole hydraulic tests within fixed packer intervals, and ii) petrophysical and hydromechanical properties by conducting a variety of laboratory tests on core material. In this contribution, we present preliminary results of our field and lab testing campaigns including thermal maturity-dependent hydraulic rock mass and geochemical characteristics as well as porosity and mechanical strength determinations of the clay rock.

The numerical modelling of the in-situ stress state is commonly performed for reservoir management or subsurface applications such as nuclear waste repositories. Modelling is required due to the sparsity of available stress magnitude data records in addition to the uncertain underground structures and heterogeneous material properties. Even though, geomechanical models provide an increase in confidence and allow an interpretation of the in-situ stress state, the associated uncertainties are very high.

We present an approach where, instead of just one model scenario that is a best fit to all available data (but necessarily has a poor fit to some data records), a wide range of model scenarios that each satisfies at least one data record perfectly is estimated. Then, additional indirect data on the stress state or other manifestations are added in order to assess the predictive quality of each model scenario. These can be for example Formation Integrity Tests or Borehole Breakouts. While model scenarios that have a good agreement with indirect data are preferred, those that are largely in contradiction are neglected.

Eventually, this approach can be used to increase the knowledge on the subsurface. Of all things, remaining contradictions help to identify anomalies or geographical and lithological areas where the model is not representative (yet). This allows to improve and evolve the model in a data-based way not only based on geomechanics. Thus, adding uncertainties and further indirect data to the standard toolbox empowers the significance of a model.

The NdFeB magnet world demand has doubled since 2005 to reach above 120 kton in 2020 [1]. The growing demand for REEs prompts their recycling. Sintered NdFeB permanent magnets are usually composed of above 20 wt.% Nd and a few wt.% of Pr and Dy. There are two main recycling ways for REE-based magnets. In the “short-loop process”, the main alloy is maintained in the valorized magnets, meaning that the microstructure and magnetic properties directly arise from the end-of-life product. In the “long loop” recycling process, one tries to extract the REEs from the alloy, which is the purpose of the present work.

The chemical separation of REEs from each other is difficult due to the similarity of their chemical properties. Following the encouraging results obtained by [2] in recovering REEs from NdFeB by hydrothermal treatment, we developed a geochemical approach of aqueous fluid – REE-compounds interactions based on the use PHREEQC software with the implementation of relevant REE-phases in the database. The database is tested against hydrothermal experiments on NdFeB powders with in-situ solution sampling. When reacted at 250°C and 100 bar, NdFeB powders transform into Nd(OH)₂, magnetite and Nd-borates along with large amounts of H₂. The low Nd solubility measured in the experiment is likely controlled by Nd-borates. The database will allow to investigate the effect of chlorine or CO₂ on the REE behaviour.

[1] Yang, Y. et al. (2017). J. Sustain. Metall., 3, 122-149.

[2] Maât, N. et al. ACS Sustain. Chem. Eng., 4, 6455-6462.

In the BMBF-funded project PyroLith, a methodical approach for the recovery of Li from NMC type LIB via a combined pyro- and hydrometallurgical process route is being developed. For this purpose, the cooling conditions and the chemical composition of the battery slags are optimized in the pyrometallurgical process step so that the whole Li content of the melt is enriched in the artificial, Li-rich compound lithium aluminate (γ-LiAlO₂). After comminution of the slags, the γ-LiAlO₂ is separated from the largely silicate slag matrix by flotation. The lithium is then leached out by hydrometallurgical processes and recovered as Li₂CO₃.

In order to achieve the project goal, extensive chemical and mineralogical analyses of the process samples are required, which are carried out as part of a method development at BGR. Because Li cannot be directly measured by conventional wavelength- and energy-dispersive X-ray spectroscopic investigation procedures, and amorphous components are only given as a sum in X-ray diffraction analysis, the use of several complementary analytical methods for sample characterization is necessary.

In the work presented here, it is briefly outlined how a Li- and Mn-rich slag from the simplified battery slag system Al₂O₃-SiO₂-CaO-MnO-Li₂O can be fully characterized chemically and mineralogically using QXRD, SEM-MLA, EPMA, XRF and ICP-MS. Furthermore, a rapid analytical tool based on UVC radiation or alternatively on µEDXRF is presented to determine distribution, crystal size, crystal morphology and relative content of the target phase γ-LiAlO₂ in the slags within a few seconds (UVC radiation) or within 3 hours (µEDXRF).

Zn-Pb deposits are host to a large proportion of worldwide resources of Ge and other critical metals. The Black Angel district in central West Greenland hosts several Zn-Pb occurrences, including the historic Black Angel mine, South Lakes and Kangerluarsuk, that show a previously unrecognized endowment of Ge and Bi (± Te) respectively. The carbonate-hosted MVT deposits at Black Angel and South Lakes show strong deformation and associated ore remobilisation at Upper Greenschist facies conditions (ca. 470°C), as indicated by graphite thermometry. Germanium occurs in tectonised and remobilised ore in the form of briartite, which is hosted in sphalerite and galena matrix. We studied how rock deformation and related remobilisation processes in these ore bodies lead to the redistribution of Ge and formation of briartite. Germanium was most likely exsolved from sphalerite as nanoinclusions of briartite during recrystallisation. Subsequent solid-state and fluid-assisted processes lead to formation of micrometre sized grains of briartite in sphalerite matrix, as well as up to millimetre-sized briartite aggregates. However, the nearby clastic-hosted SEDEX deposit at Kangerluarsuk shows native bismuth and tellurides hosted with galena, and no briartite or other Ge enrichment. Thus, two contrasting Zn-Pb systems with a different critical metal endowment are in close proximity to one another.

Laterite ore deposits in Brazil and other tropical countries contain approximately 70% of the world’s Ni and Co resources. High energy and/or reagent costs, accompanied by expensive equipment costs, are generally incurred when recovering Ni and Co via pyrometallurgy or high pressure acid leaching. Considering economic efficiency, the development of an integrated low-energy and environmentally benign biohydrometallurgical process for the recovery of these metals from laterite ores in Brazil is the aim of the German-Brazilian project BioProLat. Several acidophilic bacteria are able to use sulfur (S) as electron donor and couple the oxidation of S to the reduction of ferric iron, and are thereby capable of reducing the insoluble metal compounds to a water-soluble form. During this process sulfuric acid is generated, providing the acidic conditions that are needed to keep iron and other metals soluble. Stirred-tank bioreactor and percolation column laboratory experiments were used to optimize parameters including pH, temperature, aeration and a most suitable bacterial consortium for the bioleaching of Ni and Co. Stirred-tank laterite bioleaching at a start pH 1.5 under aerobic conditions with a consortium of different Acidithiobacillus thiooxidans strains resulted after 15 days in maximal 83 % extraction for both, Co and Ni, for 10 % (w/v) pulp density of a laterite sample from Barro Alto mine, Brazil. Eventually, the optimized process will be upscaled and reach pilot scale, transforming unexploited ores and limonite stockpiles into valuable resources, unlocking new reserves of raw materials through increasing recovery of metals from existing mines.

Epithermal ore deposits are important resources for various precious (e.g. Au, Ag) and base (e.g. Cu, Pb, Zn) metals. They form within the uppermost 1.5 km of Earth's crust by circulation of hydrothermal fluids through fractured and porous rocks in geothermal and volcanic systems. Many hydrothermal veins in epithermal deposits show evidence for pulsed ore formation events with high metal contents limited to distinct growth zones. As a particularly efficient mechanism for metal enrichment to economic grades, transport and precipitation of precious metals has been proposed to occur by isochemical contraction of a magmatic vapor phase from an underlying magmatic-hydrothermal system, where fluids can phase separate, followed by a second phase-separation event of near-surface boiling. Numerical models can provide unique insights into the temporal and spatial relationships of ore-forming processes. We use a model for magma reservoir growth to investigate the impact of sill injection rates on the hydrothermal system. The simulations with more episodic, low injection rates (<1.3 x10^-3 km³/y) result in a highly variable fluid plume which allows almost pure magmatic fluids to migrate to shallower and cooler regions, where they can phase separate and potentially form epithermal ore deposits. The modelling results point towards a relatively short time span of potential ore formation of a few thousands of years until the magmatic fluid plume retreats. Long-lived magma reservoirs which are forming at higher injection rates hamper the formation of high-grade epithermal deposits, but are more favourable for high-grade porphyry Cu deposits.

The Erzgebirge-Vogtland metallogenic province covers a wide variety of tin mineralization (greisen-, vein- and skarn-type) and represents one of the classic Sn regions in the world. The Gottesberg Sn(-W) greisen deposit is located on the western rim of the Eibenstock granite pluton. The multistage Sn mineralization of Gottesberg is closely spatial and temporal related to multiphase intrusions of subvolcanics and brecciation, controlled by a crosscutting area of major deep fault zones. For this work, lamprophyric dikes from latest drill core of Saxore Bergbau GmbH were sampled. Microscopic investigations were supplemented by the method of MLA (Mineral Liberation Analysis). Geochemical analyses of major and trace elements were performed. Previous work focused primarily on the Gottesberg Subvolcanic Suite (rhyolites and microgranites) whereby this work provides the first modern study of lamprophyres from the deposit and their age relationship to other magmatic events and the Sn(-W) mineralization. The porphyritic lamprophyres occur in dikes up to 3.5 m thick, carry xenocrysts of the granite, microgranite and rhyolite, and are partly strongly altered. Amphiboles were replaced by biotite. In the contact with the granite, the dikes form a chilled margin consisting mainly of biotite. Alteration phenomena on the groundmass and xenocrysts were studied. Cassiterite-quartz-sulfide veinlets and enclaves of granite and rhyolite in lamprophyric dikes provide information on the age position of the rocks. Overprinted lamprophyres show Sn and Rb contents >1,000 ppm and F contents up to 1.10 wt.%. Lamprophyre samples with high Zn contents (2.090-3640 ppm) show relatively high In contents (5-15 ppm).

The magmatic-hydrothermal transition is an important but poorly-understood process in the formation of Sn-W, Nb-Ta and Li deposits associated with evolved granites and pegmatites. Theory predicts that boron isotopes will fractionate between magma and fluid, so the magmatic-hydrothermal transition may be recorded in the borosilicate mineral tourmaline, which is widespread and common in these kinds of deposits. The key information needed to interpret the tourmaline record is the B-isotope fractionation between granitic melts and the fluids derived from them but former experimental studies on B-isotope fractionation between the relevant phases are not in agreement (e.g. Kowalski and Wunder, 2018, Maner and London, 2018).

This study fills this gap by an experimental, multivariant approach. We synthesized a glass of haplogranitic composition (Ab₄₀Or₂₅Qtz₃₅) and produced variants of water content (0, 4 and 6 wt%), aluminum saturation (ASI 0.7, 1, 1.3) and boron concentration (2 and 5 wt%). For each composition we determined the coordination environment of B in the glass and the fractionation of B isotopes between the respective melt and aqueous fluid at near-solidus temperature. The first part of the study was the chemical characterization and analysis of B coordination in the glasses. The NMR analysis of ¹¹B indicates that the coordination of ¹¹B is dominantly trigonal in all glasses, but there is an increase of tetrahedral coordination with increasing boron concentration and water content. Fluid-melt fractionation experiments are ongoing and first results will be presented.

South Harz Potash Limited (SHP) is a publicly listed company on the Australian Securities Exchange (ASX). Through its wholly-owned subsidiary Südharz Kali GmbH, the Company holds the Ohmgebirge mining licence in the north-western part of the Thuringian Basin, a region with more than 100 years of history of mining Permian potash deposits.

Based on the available historical exploration data, the potash resource at the Ohmgebirge was categorised by Micon International Co Limited in 2019 as an Inferred Mineral Resource in accordance with the guidelines of the Australasian JORC Code (2012).

In order to increase the level of geological knowledge and the confidence in the existing drill hole and assay database and to advance the project, two confirmation holes were drilled in 2022. The successful drilling demonstrated a good comparability of lithostratigraphic, mineralogical and geochemical data with the historic exploration data. Combining the existing and new data sets, the geological model has been updated, allowing an upgrade of a substantial proportion of the Ohmgebirge Mineral Resource estimate from the Inferred to the Indicated classification.

Currently, SHP is collaborating with experienced consultants to prepare a feasibility study which will consider all relevant technical, economic, social and environmental aspects of the project in order to transform the Mineral Resource to a Mineral Reserve according to JORC (2012). To increase awareness of the importance of mining local raw materials, we communicate transparently and regularly with the regional public and all stakeholders on our project advancements.

The United Nations Framework Classification for Resources (UNFC) is an assessment tool for mineral resource endowments, originally developed for side-projects concerning geogenic resources, such as mines. Given the integration of UNFC into the Critical Raw Material Act, it is crucial to develop a standardized classification method for secondary raw materials. However, the current framework lacks concrete guidance and primarily relies on mining sector definitions. This leads to the inconsistent use of various factors and methods in case studies, resulting in diminished comparability. To understand the requirements and challenges of the application on secondary raw material projects and address the recent assessment of aluminium as critical, a pioneering case study is conducted on a novel aluminium sorting plant using laser-induced-breakdown-spectroscopy to enable alloy specific sorting of old scrap.

The UNFC assessment bases on three criteria: "Environmental-Socio-Economic Viability," "Technical Feasibility," and "Degree of Confidence in the Estimate”. In this study the criteria are evaluated with newly developed and existing factors such as quantity, quality, supply continuity, technology, infrastructure, and socio-economic, legal and environmental aspects, using assessment methods like technology readiness level and material flow analysis. This results in a concrete guidance covering data demand, data sources and assessment tools.

The study's results will highlight the distinct requirements that differ from those of the mining sector and contribute to the development of a modified methodology. These advancements aim to enhance the applicability of UNFC, enabling comprehensive evaluations of different types of resources and projects and promoting informed decision-making towards a circular economy.

With its long mining history, Germany is a country with an important tradition in the field of mining science. The "Working Group on Geoscientific Aspects in Mining Areas" has been dealing with the remnants of mining and the resulting subsequent uses since it was founded in 1995. The task of the working group is to bring together geoscientists and other experts from the mining industry, from mining and geology-related administrative departments and research institutions for an interdisciplinary exchange of ideas and experience.

The first meeting of the Working Group on Mining Consequences took place in Upper Lusatia on the landscapes resulting from lignite mining. The thematic range of further events expanded to include ore, salt, uranium, hard coal and earths and stone mining, oil and natural gas extraction, and the search for a final repository for radioactive waste.

The meetings of the working group combine theory and application in a very practical and illustrative way. Thematically diverse technical presentations and a full-day excursion to geological outcrops, historical or operating mining facilities and post-montane landscapes are the basis for intensive exchange among the participants.

In 2023, the Working Group on Mining Consequences looks back on 51 successful meetings in different mining regions of Germany, attended by about 5,000 professional colleagues from the geo- and mining sector, nature and geotope conservation, geoparks and many other disciplines. A conference volume with excursion guide is published for each meeting in the EDGG series.

The transition towards renewable energy sources has led to a growing need for effective energy storage systems to ensure a stable and reliable power supply. Solar and wind power, although abundant, are intermittent, causing fluctuations in electricity generation. To mitigate this issue, energy storage solutions are required to store surplus energy during periods of low demand and release it during times of high demand. This research focuses on repurposing abandoned open pit coal mines as Hybrid Pump Hydropower Storage (HPHS) systems, where the mine pit functions as the lower reservoir.

The stability of the slopes in these repurposed mines is a critical factor for the successful implementation of HPHS. The presence of water in the lower reservoir and the potential inflow of groundwater play significant roles in determining slope stability. An analytical and numerical model has been developed to assess the slope stability in the selected mines for HPHS operations. Various factors, including fluctuating groundwater levels, reservoir filling levels, and different loading conditions, have been considered in the analysis.

The findings of this study contribute to a better understanding of the impact of these factors on slope stability in HPHS applications.

Nachdem die Kalidüngemittelproduktion in den 1860er Jahren in Staßfurt, im nördlichen Harzvorland, ihre weltweite Premiere erlebte, sich zunächst auf das sogenannte Nordharz-Kalirevier beschränkte, begann auf Betreiben des preußischen Bergbeamten Pinno - und entgegen der damaligen akademischen Lehrmeinung Ochsenius’ - schon in den 1880er Jahren die Erkundung der südlich des Harzes gelegenen Kalivorkommen. Die erste Bohrung Hochstedt wurde westlich Nordhausen bei Günzerode platziert und im November 1888 eingestellt ohne Kalisalze erreicht zu haben. Die zweite Bohrung bei Kehmstedt traf im Juli 1889 ein 63m mächtiges Kalisalzlager an. Bis November 1897 folgten weitere 64 Erkundungsbohrungen in über 50 Gemarkungen bis das erste - vom Preußischen Staat finanzierte - Bohrprogramm im November 1897 mit dem Nachweis der großflächigen Verbreitung bauwürdiger Hartsalz- und Carnallitit-Vorräte erfolgreich abgeschlossen wurde.

Bereits kurze Zeit nach der ersten fündigen Kalibohrung im preußischen Hoheitsgebiet des Südharz-Revieres startete auch die erste privatrechtliche Kapitalgesellschaft die Bohrerkundung auf Kalisalze im August 1891 bei Jecha, Fürstentum Schwarzburg-Sondershausen. Die Bohrung erreichte in 626,20m Teufe ein über 12m mächtiges Carnallitit-Lager, was für den Markscheider, Bergbauunternehmer und Brauereibesitzer Brügmann aus Dortmund als hinreichender Bauwürdigkeitsnachweis genügte, so dass bereits im Mai 1893 mit dem Teufen des ersten Kalischachtes im Südharz-Revier begonnen wurde. Die bergmännische Gewinnung der Kalisalze begann ab 1896 auf dem nach ihm benannten Brügmann-Schacht der Gewerkschaft "Glückauf" in Sondershausen, worauf rasch weitere Bergwerke folgten. Bereits 1914 verfügte das Südharz-Revier über 33 Schächte, zum Jahreswechsel 1924/25 waren es bereits 50 vollendete Schachtanlagen mehrerer Kaligesellschaften, die in der Folgezeit verschiedene, auch staatlich gelenkte Konsolidationen und Stilllegungen erfuhren.

Die Südharz Kali GmbH, eine 100%ige Tochtergesellschaft der South Harz Potash Ltd., eine in Australien gelistete Aktiengesellschaft, hat 2017 das Bergwerkseigentum (BWE) Ohmgebirge erworben und beabsichtigt dort die Gewinnung von Kalisalzen. Das BWE Ohmgebirge grenzt im SW bzw. W an die Grubenfelder der ehemaligen Kalibergwerke Bischofferode und Sollstedt. Dort wurden bereits Ende des 19./Anfang des 20. Jahrhunderts, zwischen 1956 und 1965 und in den 1980er Jahren in mehreren staatlich finanzierten Erkundungskampagnen wirtschaftlich interessante Kalisalzvorräte nachgewiesen. In den Jahren 2017 und 2019 erfolgte zunächst die Neubewertung dieser historischen Erkundungsdaten. 2022 wurden zwei neue Tiefbohrungen abgeteuft, durch die die Resultate unmittelbar benachbarter historischer Bohrungen aus den Jahren 1906 und 1983 bestätigt wurden.
Im Posterbeitrag werden die Erkundungsstrategie und die Resultate der jüngsten Bohrerkundung im Südharz-Kalirevier vorgestellt.

Field observations across the globe show that drainage reversal toward a cliff is a common type of drainage reorganization. Drainage reversal occurs when a channel reverses its flow direction by 180 degrees while exploiting its antecedent valley. In these settings, fluvial deposits of the antecedent, pre-reversal drainage potentially record valuable information about the process of drainage reorganization. However, such fluvial deposits are rare because they are typically eroded by the reversed channels.

We present a spectacular case of a reversed channel in the Negev desert, Israel, that forms a narrow canyon with several-meters high vertical walls exposing a sequence of fluvial deposits that reflect the reversal process. At the base of the sequence, a <1 m thick conglomerate layer is characterized by clast imbrication consistent with the westward flow direction of the antecedent drainage. Overlying the conglomerate, reddish fine-grained sediments (~1-2 m thick) indicate a decrease in flow energy, reflecting the reversal of the flow toward the current eastward flow direction. Paleosols and scattered calcite nodules within the sediment imply phases of soil development, most likely during a more humid climate than today. The uppermost layer (<1 m thick) consists of sediments of alluvial fans fed from the neighboring hillslopes, that play a key role in the development of the reversed channel through their avulsion cycling. Using geomorphic mapping based on high-resolution DEMs and preliminary dating results, we propose a holistic approach for better understanding the relationships between sedimentary systems, climate changes, and erosional processes in landscapes experiencing drainage reorganization.

Alluvial river adjustment occurs in response to altered sediment and water inputs, driven by both natural and anthropogenic climate change, changes in land use and/or land cover, and/or imposed by tectonic boundary conditions. This river response is ultimately reflected in the geometry of the bankfull channel, the planform characteristics of the river, and the longitudinal profiles of the mainstem river and its tributaries. This study utilizes analyses of river longitudinal profiles and provides a powerful tool to detect the change and extend it to long-term landscape evolution. Wickert and Schildgen (2019) developed the model, GRLP, to compute transient and steady-state solutions for the long-profile evolution of transport-limited gravel-bed rivers with self-forming channel-width adjustments. Following an analogous approach to that taken by Wickert and Schildgen (2019) and linking sediment transport and river morphodynamics, we developed a model describing the long-profile evolution of a transport-limited sand-bed river. This sand-bed model allows for planform adjustments as a function of excess shear stress (following Parker, 1978, and Dunne et al., 2018) thereby linearizing the sediment-transport response to changing river discharge. Ultimately, the resultant equations suggest a diffusive form for sand-bed river long-profile form and evolution. Both models were further built to work with the Landlab component library. Here, with these Landlab compatible models, we further present examples of sand- and gravel-bed river long-profiles under a variety of water- and sediment-supply boundary conditions, and present the transition into models of linked tributaries reproducing river-network evolution over both human and geological time scales.

The width of fluvial valley-floors is a key parameter to quantifying the morphology of mountain regions. Valley-floor width is relevant to diverse fields including sedimentology, fluvial geomorphology, and archaeology. The width of valleys has been argued to depend on climatic and tectonic conditions, on the hydraulics and hydrology of the river channel that forms the valley, and on sediment supply from valley walls. Yet, so far, a physically-based model that can be used to predict valley width is lacking. Here, we derive such a model and test it against three different datasets. The model applies to valleys that are carved by a river migrating across the valley floor, and includes the effects of uplift and lateral hillslope sediment supply. Valley width is controlled mainly by the mobility-uplift number, which is the ratio between lateral channel mobility and uplift rate. At high values of the mobility-uplift number, the valley evolves to the channel-belt width, which is the width of the area actively reworked by the river in an unconfined setting. At low values of the mobility-uplift number, valley width corresponds to channel width. Between these limits, valley width is linked to the mobility-uplift number by a logarithmic function. We compare the model to independent data sets of valleys in experimental and natural uplifting landscapes and show that it closely predicts the first-order relationship between valley width and the mobility-uplift number.

Any keen observer has noticed that valleys show a large variability in their shapes, explained by the incision and widening processes. However, valley widening processes and rate are still poorly documented while valley evolution has a key role in geomorphological processes (contribution to the formation of abrasion terraces and establishment of ecosystems) and global geochemical cycles (increase of carbon storage in wide valley and buffering sediment fluxes transported to the oceans). Given these issues, it is becoming truly necessary to better understand valley widening rate and its controls.

For that, we focused on several river valleys (in the Arequipa Province, Peru, and in the plateau of Valensole, France) and we have used and further developed the approach tested in northern Chile by Zavala et al. (2021). We collected samples from valley flanks to measure the millennial erosion rates, by using in-situ produced Beryllium-10 and Aluminium-26, and analysed 10-Be and 26-Al concentrations to estimate the local valley flank erosion rate.

We also extracted different factors that may control widening rate (valley width, slope of flanks and valley floors, incision and drainage area, etc) in order to compare these factors to 10-Be and 26-Al concentrations. Our preliminary results show comparable 10-Be concentrations along a single stretch of valley, except for several outliers, for different valleys in the Andes and France, indicating some robustness in the sampling method. These results are promising and will provide new answers, by integrating more metadata, about what controls the widening rate of valleys and how.

The depositional architecture and geomorphology of alluvial fans that have evolved in response to similar regional environmental conditions can differ strongly, implying that autogenic processes may play an important role and lead to similar cycles of fan aggradation and incision that may be difficult to be distinguished from the effects of tectonics or climate change. Here we present new data from two different Late Pleistocene (33-18 ka) alluvial fan systems in northern Germany. These fans formed under similar climatic and tectonic conditions, but differ in size, type, and drainage area allowing to estimate the role of climate and autogenic controls on flow processes, facies architecture, and fan-stacking patterns.

Sand-rich, sheetflood-dominated fans are related to larger, low-gradient fan catchments. Steep depositional fan slopes (5°-17°) favored supercritical flow conditions. Steep, dip-slope catchments enhanced stream gradients and promoted the transport of coarser-grained sediments. These fans have lower gradient slopes (2-6°) and are dominated by channelized flows, alternating with periods of unconfined sheetfloods. Fan onset and aggradation occurred in response to climate change at the end of MIS 3. Meter-scale coarsening-upward successions are characterized by sandy sheetflood deposits at the base and overlain by multilateral or smaller single-story gravelly channel fills are related to high-frequency climatic fluctuations or seasonal fluctuations in water and sediment supply. In contrast, the recurrent pattern of multistorey, multilateral, and single-storey channel bodies with a lateral offset to vertical stacking pattern most probably was controlled by autogenic switch in an avulsion-dominated system.

Reconstructing sea water temperatures from carbonate derived δ¹⁸O_C is a widely used approach in paleo-environmental studies. However, converting δ¹⁸O_C to water temperatures requires information about the isotopic composition of the sea water (δ¹⁸O_SW), which usually can only be estimated for paleo-environments. Especially in shallow marine settings δ¹⁸O_SW can potentially be altered by a strong seasonal variability of fresh water supply. Dual clumped isotopes (Δ₄₇+Δ₄₈) can be employed to determine seawater temperatures independent of δ¹⁸O_SW, as isotopic clumping is independent of the bulk isotopic composition of seawater.

In the current study we aim to resolve the seasonal variability of δ¹⁸O_SW by the combined measurement of δ¹⁸O_C and dual clumped isotopes (Δ₄₇+Δ₄₈) in Eocene bivalve shells (Venericor planicosta) from the Paris Basin. To determine seasonal variations and to detect annual extrema, δ¹⁸O_C was measured along the shell. Based on the δ¹⁸O_C record, annual extrema were resampled for dual clumped analysis.

The analysed bivalve revealed a pronounced seven-year seasonal cycle in δ¹⁸O_C, yielding an average annual amplitude of 2.5‰. Translating this seasonal range to sea water temperatures, applying a constant δ¹⁸O_SW, results in an annual temperature amplitude of ~11°C. The dual clumped isotope measurements, however, point to a more damped seasonal temperature range (~4°C) and a variable δ¹⁸O_SW with a seasonal difference of ~1‰.

The Δ₄₇+Δ₄₈-based seasonal temperature amplitude agrees with an Eocene warm-house climate and a considered weaker latitudinal thermal gradient. Reconstructed δ¹⁸O_SW exhibits high seasonal variability, indicating the periodic influx of isotopically lighter fresh water into the Paris Basin.

Sedimentary archives from marine sinkholes enable long-term reconstructions of past storm activity. In the last years, numerous cyclone-frequency reconstructions have been obtained from sediment cores collected in blue holes located in the circum-Caribbean region. Such structures work as sediment traps for allochthonous particles, mobilized through storm waves and surges from adjacent areas by passing cyclones. The 320 m wide and 125 m deep Great Blue Hole (Lighthouse Reef, Belize) is an outstanding cyclone-frequency archive worth exploring due to anoxic bottom-water conditions and the opportunity to recover annual deposits spanning the Holocene interglacial and even parts of the late Pleistocene. In June 2022, a 30-m-long sediment core (BH8) was extracted from the sinkhole and dated to 12.5 ka BP at its base. Sedimentological and palynological analyses point to an initial cenote-like setting that experienced a rising marine influence starting around 7.2 ka BP, which led to brackish and restricted marine conditions until 5.7 ka BP. Afterwards, full marine conditions have persisted in the Great Blue Hole to present day. Our sediment-core analysis resulted in a 12000-years-long paleoenvironmental reconstruction at annual resolution. Several warm climate periods of this timeline represent past equivalents for the current situation of rising ocean temperatures. In the SW Caribbean, cyclone frequency changed from a rather variable and less active stage (12.5-3.5 ka BP) to a more stable and active state (3,5-0 ka BP). This bipartite pattern is surprisingly best explained by latitudinal changes of the Intertropical Convergence Zone (ITCZ) from a northern towards a southern location.

The Layla Lakes (300 km S Riyadh) had been fed by fossil groundwater until they dried up in the 1990s due to agricultural water abstraction, revealing a series of 22 sinkholes. At their walls, well stratified to laminated sediments became exposed, unlocking a hitherto unexplored paleoenvironmental and paleoclimatic archive in the center of the Arabian Peninsula.

In November 2022, sedimentary logs were recorded, including on-site spectral gamma-ray and magnetic susceptibility measurements. From four sinkholes, >600 samples were taken to unravel the geochronological, mineralogical, geochemical, and palynological evolution of the lakes at high resolution. Lithofacies analysis shows changes between laminated lake sediments and weakly stratified sebkha deposits composed of sulfates (gypsum, anhydrite), carbonates, siliciclastic components, and bioclastic remains (shells, chironomidae tubes).

Initial radiocarbon dating indicates that the laminated lake sediments comprise a time interval from recent to 300 a A.D., suggesting at least partly varve-type sediments. The sebkha facies with short lacustrine intervals covers the entire Holocene. Different sections can be stacked together by high-resolution 3D-models, generated from a drone survey (cooperation with KAUST, Saudi Arabia). Based on field observations and first data analysis, a multi-stage paleolake model is suggested: Triggered by faults in the underlying Lower Jurassic Hith, anhydrite converts into gypsum, forming a topographic bulge and a sebkha environment. During fall of the groundwater level, sinkholes collapsed in its center due to phreatic dissolution, forming the groundwater-fed lakes. All sections show a pronounced cyclicity which will be further analyzed by high-resolution multi-proxy analyses.

Anthropogenic warming is predicted to increase the frequency and intensity of tropical cyclones, leading to severe damage and loss of life. However, projections based on historical observations are limited due to the lack of longer-term and spatially-resolved data. Here, we use the Toarcian Oceanic Anoxic Event (T-OAE) as a case study to investigate the link between tropical cyclone patterns and climate change. The T-OAE is a well-studied example of intense global warming and environmental change in Earth's history, characterized by a 7°C increase in sea-surface temperature and the common occurrence of tropical cyclones recorded in sedimentary deposits.

We collected sedimentary outcrop data along a 60 km-long transect, comprising 10 detailed sections along the paleo continental shelf in the central High Atlas in Morocco. We used sedimentary characteristics such as grainsize, texture, sedimentary features, and ichnofossils to identify storm-generated strata in offshore to lower shoreface settings, and extract paleo-tropical cyclone parameters. To constrain the age model, we used a cyclostratigraphic approach based on magnetic susceptibility datasets. By comparing the results to pre- and post-T-OAE time intervals, we gained insights into the frequency and intensity of tropical cyclones during this event and how they may have been affected by climate warming.

Our study highlights the potential of outcrop data to extract past storminess characteristics and test current model predictions on tropical cyclone patterns. By improving our understanding of how climate change affects tropical cyclones, we can better prepare for and mitigate the damage caused by these extreme weather events.

The last deglaciation is an ideal time interval to investigate the effect of climatic and oceanic disturbances occurring at high latitude on the hydrological regimes of the Mediterranean Sea. In particular, a series of disruptions of the Atlantic Meridional Oceanic Circulation (AMOC) has punctuated the transition from glacial to interglacial conditions, with the so-called 8.2 ka event being the youngest one. After the publication of recent results showing the existence of instable climatic conditions in the Dead Sea during the Younger Dryas (Müller et al., 2022), we examine here the environmental record during the 8.2 ka event to illuminate the effects of the background climate (colder to warmer) on hydrological distrubances linked to AMOC disruptions. We performed a coupled limnological and geochemical analysis of sediments deposited in the deeper part of the Dead Sea (ICDP site 5017A), which showed the occurrence of repeated mass wasting deposits related to intense erosive activity in the watershed of the Dead Sea. Newly-acquired neodymium and strontium isotopes also show a rapid change in sediment provenance and a hiatus in outcrop sequences from western lake shores suggests a drop in lake level at that time (Migowski et al., 2006). Ongoing classification of mass wasting events and the integration of other well-dated regional records and paleoclimatic simulations will provide additional insights on the erosional processes operating at that time, as well as the climatic regimes associated.

DeepStor-1 is the exploration well to the Helmholtz research infrastructure “DeepStor”. DeepStor focuses on the investigation of high-temperature heat storage marginal to the former oil-field “Leopoldshafen“. It is located about 10 km north of the city of Karlsruhe (Germany).

The DeepStor-1 well will probe marine to continental syn-rift sedimentary successions. It is planned to reach the Pechelbronn Group at 1‘460 m. Seismic investigation reveal a structurally undisturbed section that below 200 m depth covers the Landau, Bruchsal, Niederrödern and Froidefontaine Formations. Cores will be taken from the entire section below 820 m resolving about 6 Myr (about 26-32 Ma) of the Oligocene (about 23-34 Ma) and revealing an important geoarchive on regional and global signals, evolutionary trends of plate tectonics, paleolife, and paleoclimate. In addition to coring, the logging program is planned to include besides technical logging, a caliper-, self-potential-, temperature-, dual latero-, natural gamma spectrometry-, neutron-gamma porosity-, sonic-, elemental capture spectroscopy-, as well as image-logs in the sections 215-820 m as well as in the cored 820-1460 m section. Drilling of DeepStor-1 is planned between 2023 and 2024. Besides the interest of the Helmholtz Association in

1. the characterization of the subsurface by logging and coring,
2. the evaluation of the structural, hydraulic, and hydro-chemical set-up and the boundary conditions of the reservoir, and
3. short and long-term testing of hydraulic and thermal performance of the reservoir,

the well offers opportunities for more fundamental investigations on the climatic and geological conditions during deposition of the reservoir rocks.

We report abundant small calcareous mounds associated with fossilized kerogenous microbial mats in tidal-facies sandstones of the predominantly siliciclastic Moodies Group (ca. 3.22 Ga) of the Barberton Greenstone Belt (BGB), South Africa and Eswatini. Most of the bulbous, internally microlaminated mounds are several cm in diameter and formed at the sediment-water interface contemporaneous with sedimentation. They originally consisted of Fe-Mg-Mn carbonate which is now largely silicified; subtle internal compositional laminations are composed of organic matter and sericite. Their presence for >6 km along strike, their restriction to the inferred photic zone, and the internal structure suggest that mineral precipitation was induced by photosynthetic microorganisms. Similar calcareous mounds in this unit also occur within and on top of fluid-escape conduits, suggesting that carbonate precipitation may either have occurred abiogenically or involved chemotrophic metabolism(s) utilizing the oxidation of organic matter, methane, or hydrogen, the latter possibly generated by serpentinization of underlying ultramafic rocks. Alternatively or additionally, carbonate may have precipitated abiotically where heated subsurface fluids, sourced by the intrusion of a major Moodies-age sill, reached the tidal flats. In summary, precipitation mechanisms may have been variable; the calcareous mounds may represent “hybrid carbonates” that may have originated from the small-scale overlap of bioinduced and abiotic processes in space and time. Significantly, the widespread occurrence of these stromatolite-like structures in a fully siliciclastic, high-energy tidal setting broadens search criteria in the search for life on Mars while their possible hybrid origin challenges our ability to unambiguously identify a biogenic component.

We studied two fine-grained calcite hardgrounds (Hg1, Hg2) from the upper part of the Early to Late Cretaceous Natih Formation. Both hardgrounds occur in a 60-m-thick succession of limestones, comprising the Natih members C, B and the basal part of A. The hardgrounds of interest are positioned in the members C (Hg1) and B (Hg2) and typified by abundant borings of homogenous distribution, filled with dolomite. They occupy the upper part of a mudstone to wackestone bed (Hg1) and a wackestone bed (Hg2), respectively, above which the grain size increases. Field work, petrographic, microfacies and cathodoluminescence analyses, allowed us to shed light on the their unusual great thickness (75 and 100-120 cm, respectively) as the thicknesses of such fine-grained horizons may generally represent barriers for calcite-precipitating fluids. The logged section represents a protected/lagoonal environment with a relatively low sedimentation rate as indicated by the hardgrounds, peloidal limestones and bioturbation-related nodular bedding. The hardgrounds contain sponge spicules, which we did not encounter elsewhere. The two hardgrounds formed by minor sediment aggradation of locally produced mud-rich sediment, in which near-surface cementation was able to keep pace with aggradation. These conditions were met due to the Cretaceous calcite sea water composition, tropical climate, relatively low relative sedimentation rate and relative sea-level rise shifting the depocenter landward. Episodic sea-level rise was caused by regional plate convergence. Slab-pull and pulsed thrust-loading caused down-bending of the platform twice and formation of the two hardgrounds. Temporary down-bending events were followed by isostatic rebound.

Understanding ancient climate changes is hampered by the inability to disentangle trends in continental ice volume from records of relative sea-level change. As a unique coastal deposit in tropical and subtropical regions, beachrock has been proved to be reliable for constraining the glacial meltwater signal and, thus, the total volume of land-based ice in the Quaternary. However, beachrock is rarely recognized in the fossil record due to (a) the 2-dimensional distribution of beach deposits, as opposed, for example, to extended platform sediments, and (b) the fact that specific environmental conditions are required in order to lithify sediments directly at the beach.

By combing the stratigraphic architecture with petrography of characteristic cements, we show the first Ordovician beachrock from the Tarim Block, northwestern China. According to biostratigraphic data, a middle Katian (Upper Ordovician) palaeokarst surface is capped by a carbonate conglomerate beachrock, indicating a significant late Katian relative sea-level rise.

These beachrocks can be correlated with the onlap on the widespread subaerial exposure surfaces during deglaciation and post-glacial sea level rise. They formed in northwestern Tarim Basin after a pronounced stratigraphical gap reflecting the expression of a Katian glacial. We suggest that the beachrock ‘fingerprinted’ a strong melt-water pulse in high latitudes after this short-lived glaciation, which until now did not receive much attention in the scientific literature.

The world’s largest ammonite, Parapuzosia (P.) seppenradensis (Landois, 1895), has fascinated the world ever since the discovery in 1895 of a specimen measuring 1.74 metres (m) in diameter near Seppenrade in Westfalia, Germany. Subsequent findings of this taxon have been exceedingly rare and its systematic position has remained enigmatic. We have revised the historical specimens and documented abundant new material from England and Mexico. Our study (Ifrim et al., 2021) comprises 154 specimens of large (< 1 m diameter) to giant (> 1m diameter) Parapuzosia from the Santonian and lower Campanian, mostly with stratigraphical information. High-resolution integrated stratigraphy allows for precise trans-Atlantic correlation of these occurrences, and the Tepeyac section has become Associated Stratotype Section and Point for the base of the Campanian (Gale et al. 2023). It yields a rich macrofossil assemblage (Ifrim and Stinnesbeck, 2021) which is correlated to other parts of the world by the stable carbon isotope curve, and also to the successin of the German Münsterland Basin where the World's largest ammonite originates. The high- resolution correlation allows for further insight into the palaeobiology, evolution and dispersal of worlds largest ammonite.

The early Mississippian of the Aachen region is characterized by a tropical shallow-water carbonate succession, the so-called Kohlenkalk Platform. Establishing a second phase of intensive carbonate production, it follows on the Givetian to Frasnian biostromal buildups around the southeastern edge of the London-Brabant Massif. The timing and patterns of the development of these Carboniferous carbonates were studied, based on drill core Gressenich BK1. It was sunk by the Geological Survey of North Rhine-Westphalia in the core of the Burgholz Syncline and reached a depth of 100 metres. The borehole is located in the Vygen/Gressenich Quarry, which exposed and strongly tectonized Devonian strata were previously investigated by Reißner (1990). In contrast to the nearby active Hastenrath Quarry, the Palaeozoic part of the succession shows an inverted stratification. As Holocene sediments comprise a thickness of 7.30 m within the drill core, subsequent Devonian sedimentary rocks (mostly reefal limestones) occur up to a depth of 27.00 m. Followed by 12.40 m of black shale of unclear stratigraphic age, possibly the Frasnian Matagne Shale, all formations and subformations of the drilled Kohlenkalk succession can be easily subdivided by lithostratigraphy. Considering the regional stratigraphic schemes in the Vesdre Massif of eastern Belgium and referring to the formal lithostratigraphic concept of Amler & Herbig (2006), these are the Vesdre and Terwagne formations. The latter contains the Hastenrath (= Vaughanites Oolith), Bärenstein, and Bernardshammer subformations. Unfortunately, conodonts are rare or absent. In the case of the Vaughanites Oolith, reworking processes cannot be ruled out.

In northern Germany, Lower Cretaceous sediments are predominantly represented by CaCO₃-poor mud- and siltstones of up to 2000 m thickness, which become more carbonate-rich during the Albian-Cenomanian transition and even chalkier in the upper Cenomanian. The sedimentary system can be simplified considered as bimodally controlled by carbonate and fine-grained siliciclastics; in addition, some lithostratigraphic units are characterized by a high organic carbon content (Hoheneggelsen Formation, Barremian-Lower Aptian; Hesseltal Formation, Cenomanian-Turonian).
We present a 1500-m-thick composite record of late Berriasian to middle Turonian age based on 14 drill cores and about 4500 samples. All cores and successions are located in the larger Hanover area, which represents the depocenter of the North German Lower Saxony Basin in early to mid-Cretaceous times. Beside a recently published long-term carbon-isotope stratigraphy, we generated high-resolution calcium carbonate and organic carbon data, which nicely trace the lithostratigraphic units on formation and on member level, allowing for a more detailed characterization for most of the units. Only the Albian-Cenomanian transition from the Peine to the Herbram Formation is less well developed in the geochemical data.

The Danubian Cretaceous Group (DCG; Bavaria, SE-Germany) represents the deposits of one of the most pronounced sea-level rises in the Phanerozoic. Integrated stratigraphy (litho-, sequence-, and chemostratigraphy) and (micro-) facies analysis of the Lower Cenomanian–Middle Turonian strata of the DCG based on new drill cores from the north of Regensburg and the Grub section in the Bodenwöhrer Senke provides new insights in the process linked to the early Late Cretaceous sea-level rise.

Unconformably overlying Jurassic carbonates or Variscan granites, the Cretaceous succession includes the Regensburg (Lower Cenomanian–Upper Cenomanian), Eibrunn (uppermost Cenomanian–lowermost Turonian), Winzerberg (Lower Turonian) and partly Kagerhöh and Roding (Middle Turonian) formations. All lithofacies is of marine origin and consists of glauconitic sandstones, argillaceous marlstones, silty-spiculitic wackestones to marlstones, fine-grained (marly) sandstones, glauconitites and bioclastic wackestones. Five Cenomanian–Turonian sequence boundaries and their corresponding depositional sequences have been identified. Their correlative nature on an intra-basinal scale and beyond suggests a eustatic control of the depositional processes. High-resolution carbon stable isotope-based chemostratigraphy through the Cenomanian to Lower Turonian considerably improves correlation to nearby sections and European reference sections in southern England and France. A nearly complete record of the Oceanic Anoxic Event 2 (OAE 2) allows a detailed stratigraphic calibration of the Cenomanian–Turonian boundary interval and provides new insides into the environmental processes associated with OAE 2 in the Danubian Cretaceous Basin, including the first proof of the Plenus Cold Event from the region.

The widespread deposition of Lower Toarcian (Early Jurassic) black shales throughout NW Europe has often been associated with a global oceanic anoxia event, the Toarcian Oceanic Anoxic Event (T-OAE). However, sedimentary variations within the European sub-basins suggest a significant influence of regional effects, arousing interest in investigating regional variations in the NW European basin system. At the Hils syncline (Lower Saxony Basin), black shales of the Posdionienschiefer Formation have been studied extensively in recent decades, mainly focusing on the effect of thermal maturation on organic-rich sediments. However, under- and overlaying organic-lean clay- and mudstones are sparsely studied in this region.

This study investigates a continuous profile of Upper Pliensbachian to Upper Toarcian/Lower Aalenian deposits by combining samples from two boreholes from the Hils syncline, Wickensen and BO2.0, to establish a regional model for the deposition of Lower Toarcian black shales in this region. Nearly 200 samples were analyzed using a multi-disciplinary approach, including X-Ray fluorescence, C_org isotopic composition, Rock-Eval pyrolysis, and biomarker analysis.

The geochemical results suggest that the development of anoxia was closely linked to sea level and associated water circulation variations. Upper Pliensbachian and lowermost Toarcian sediments were deposited under oxic conditions associated with increased terrestrial influx and a low sea level. The overlying black shales (falciferum zone) are characterized by prevailing anoxia and photic zone anoxia and decreased terrestrial input, indicating a sea level rise. For the overlying Upper Toarcian Jurensismergel shales, ongoing sea-level rise is suggested, promoting less restricted water circulation and dysoxic conditions.

The sequence stratigraphic and facies analyses of the Lower Cenomanian to Upper Turonian core section HG 7025 provide a new standard section of the regional facies development and stratigraphic architecture in the so-called “Faziesübergangszone” (facies transition zone) of the Saxonian Cretaceous Basin. The section covers eight depositional sequences, divided by nine sequence-bounding sedimentary unconformities (SBs). The Lower Cenomanian depositional sequences DS Ce 1+2 and DS Ce 3 comprise the lower and upper fluvial Niederschöna Formation, separated by sequence boundary SB Ce 2. Above SB Ce 3, the Middle Cenomanian Wurmsandstein (DS Ce 4) displays the first marine influence in the succession. Intensifying this trend, the marine onlap continues during the early Late Cenomanian DS Ce 5, almost completely levelling the pre-existing paleo-topography. DS Ce 5 ends at SB Ce 5, representing a subaerial unconformity. Cenomanian marine onlap is completed by the plenus transgression during DS Ce-Tu 1, culminating in the lowermost Turonian Lohmgrund Horizon. The transition from Lower to Middle Turonian is marked by the regionally correlatable Bielatal Horizon of the Schmilka Formation (SB Tu 1). Both early Middle Turonian DS Tu 2 and Middle to early Late Turonian DS Tu 3 are defined by rapid sea-level rises and subsequent pronounced progradation phases. Separated by a subaerial unconformity (SB Tu 3), DS Tu 4 comprises a trans-/regressive cycle capped by SB Tu 4, marked by a sharp grain-size increase at the base of Sandstein c3. The Late Turonian DS Tu 5 is only represented by lowstand and early transgressive deposits.

The strata of the Danubian Cretaceous Group reflect dynamic depositional conditions in a peri-continental setting at the northern margin of the Alpine Tethys. From the Middle Turonian onwards, tectonic inversion along the Franconian Lineament started, reflected by the deposition of coarse-grained and extremely immature siliciclastics of the continental, more than 466 m thick Hessenreuth Formation, comprising the mid-Middle Turonian–Middle Coniacian depositional sequences DS Tu 3–Co 2. The composite section studied consists of successions cored by the deep Friedersreuth 10/1990 borehole as well as several shallow boreholes and outcrops. The >63 m thick Glashütte Member below 312 m ASL is characterized by beige-pink, conglomeratic sandstones alternating with thin brick-red, argillaceous-silty soil horizons. The Parkstein Member (312–390 m ASL) is dominated by several-meters-thick, partly inversely graded sandstone packages, interbedded by a few thin carbonaceous silt and clay beds with plant debris. The tripartite Friedersreuth Member (390–562 m ASL) starts with a cyclic conglomeratic-brecciform debris-flow unit, followed by a chaotic mud-flow unit, and is capped by predominantly fine-grained, plant-rich siliciclastics. The uppermost ca. 153 m constitutes the Hesserberg Member, i.e., mica-rich, coarse conglomerates that include meter-scale boulders. These alluvial subunits can be correlated to the mixed marginal marine / continental succession of the Bodenwöhrer Senke, ca. 60 km in the south, and the neritic deposits around Regensburg–Kelheim. Palynoassemblages are dominated by angiosperm pollen of the Normapolles group. Below 515 m ASL, the Turonian marker Complexiopollis christae occurs, while above 555 m ASL, Minorpollis minimus characterizes the Coniacian.

A lithostratigraphic unit is a stratum or body of strata that conforms to the law of superposition and is defined based on lithic characteristics and stratigraphic position. The stratigraphic concept relies on the assumption that younger rocks are deposited on pre-existing rocks during earth's history, and that individual sedimentary layers of rather constant thickness expand laterally. This working hypothesis has been successfully applied in many sediment studies and the results have been presented on numerous geological maps. A stratigraphic approach is problematic in regional metamorphic series, since the primary stratigraphy is converted into tectonic layering during metamorphic overprint. Using the Saxon Granulite Massif as a case study, this contribution aims to demonstrate the difficulty in applying lithostratigraphic methods to high-grade metamorphic rocks. We provide a critical discussion of the arguments that favour a lithostratigraphic model for the Saxon Granulite Massif in the light of the state of the art literature. High-grade metamorphic rocks should be primarily characterized based on their macroscopic appearance and further investigated using geochronological, petrological and structural methods. Absolute age constraints can be derived from radiometric dating methods, however, it should be critically evaluated if these results reflect a protolith age, a metamorphic crystallisation age or an inherited age. Many metamorphic terrains are dominated by rocks of different ages and thus conventional principles of stratigraphy cannot be applied.

Profound climatic and environmental changes at variable timescales are documented throughout the Late Triassic to Early Jurassic (c. 210-170 Ma) and were linked to the emplacement of large igneous provinces, tectonic processes, as well as transient climate fluctuations. Climate and environmental change triggered bio- and geosphere evolution, and impacted on sedimentary archives of marine and terrestrial basins. Most severe environmental change events, involving global carbon cycle and ecosystem perturbations, occurred at Triassic-Jurassic boundary (TJB; c. 201 Ma) and during the early Toarcian Oceanic Anoxic Event (T-OAE, c. 182 Ma).

We here discuss the differential response of depositional settings and organo-facies towards secular and transient environmental change along a basin-margin transect of the NW European Epicontinental Seaway (North German Basin), an expanded and intensively structured shallow shelf sea.

Stable carbon isotope values (d¹³C_org) revealed diagnostic trends that allow the precise intercorrelation along the transect, as well as correlation with far-apart sites. The TJB and the T-OAE are indicated by prominent negative carbon isotope excursions.

Programmed pyrolysis data indicate spatio-temporal organo-facies trends that on a temporal scale occurred in response to changes in deposition, such as climate and sea level evolution, while spatial pattern reflect basin morphology and paleobathymetry. Marine organic matter is best preserved at anoxic basinal sites, while marginal settings received increased land plant contributions and/or experienced more intense oxic degradation of marine organic matter. Substantial TOC accumulations occurred only in association with the T-OAE during high sea level and were most continuous at basinal sites.

The Axial Zone of the Pyrenees represents a window into the Variscan evolution of the northern Gondwana margin. One enigma of this evolution is the origin of the many and large granitoid intrusions and gneiss domes as well as the timing of their emplacement and deformation.

New zircon U-Pb data using laser ablation ICP MS indicate that granitoid plutonism is an almost continuous process over the entire Variscan orogenesis between 360 and 285 Ma that can be statistically constrained and shown for a number of these intrusions and domes. The Bassiés pluton is a key example which shows the oldest Carboniferous intrusive units with ages of 350 - 340 Ma, followed by the main intrusion phase between 330 and 320 Ma including the magmatic peak of 321 Ma. Two further age clusters occur around 314 to 300 Ma and around 285 Ma in the early Permian.

The polyphase development and in-situ melt recycling of the granitoids can also be inferred from core-rim relationships of zircon grains. There are zircons with core and rim ages of 346 and 326 Ma or 330 and 305 Ma, respectively. According to these results, it is required to revisit the mechanisms of pluton emplacement over such a long time span as well as the definition of the emplacement age. The youngest age is clearly not the crystallization age of the pluton, but plutonism is a long-lasting process that affects the Variscan crust over tens of millions or years, i.e. during the entire orogeny.

We present new results from a fission track (FT) dating approach on zircon and apatite from the Thuringian Forest, a prominent fault-bounded basement high in central Germany, and its southwestern periphery exposing Mesozoic strata. Samples were collected from exposures of igneous rocks as well as from lower to upper Permian (Rotliegend) continental red beds and volcanics recovered from a borehole southwest of the Thuringian Forest. Apatite FT ages range between 86 and 70 Ma, suggesting rock uplift associated with a well-documented and regionally important phase of NNE–SSW-directed intraplate contraction, resulting in spatially homogeneous removal of c. 3 km of Upper Palaeozoic to Mesozoic rocks. No change in apatite FT ages was detected across the regional-scale Franconian Fault system at the southwestern margin of the Thuringian Forest. Additionally, apatite FT ages of borehole samples southwest of the Thuringian Forest from depths between 9.6 and 2.7 km range from 57 to 18 Ma, suggesting post-Late Cretaceous cooling of this peripheral region. Our data hence support recent models of a continued large-scale domal uplift of Central Germany without verifiable or detectable involvement of individual faults.

The formation of crystallographic preferred orientations (CPO/texture) in sediments is often attributed to rigid grain rotation of minerals and aggregates, plastic-brittle deformation and dissolution-precipitation processes. Especially, clay minerals have a large shape anisotropy due to their platy habit. Here, we present an experimental approach in order to quantitatively explore the influence of particle settling and subsequent compaction in an undisturbed, ideal environment.

A powder of idiomorphic kaolinite grains was mixed with a fine-ground, illite aggregates in mass proportions of 0, 30, 50, 70 and 100 % in artificial seawater. The sludges settled in 80 cm high tubes. For each composition three samples were produced: Sedimentation-only and two drained compaction experiments (30 and 60 vol-%), which were carried out in a mechanical press with uniaxial load up to 0.4 MPa and 4 - 8 MPa. The CPO of clay minerals was measured using high energy X-ray diffraction at beamline P07b at Deutsches Elektronen-Synchrotron (DESY) and pole figure data was directly extracted using single peak evaluation.

The results indicate that sedimentation alone, can yield a strong texture of the clay minerals. The increase in texture strength (TS) is decreased at higher applied loads. TS is linearly related to shortening and porosity reduction. The kaolinite TS is inversely correlated with texture-inhibiting illite aggregate content which hampers further particle rotation. It is interpreted that the initial stages of settling and early rigid body rotation during compaction are thus the most important processes in the formation of a CPO in clay rich sediments.

The topography of the Rhenish Massif is known to be affected by Late Cenozoic uplift. Recent GNSS studies imply surface uplift rates of up to 1 mm/a, likely controlled by a mantle plume beneath the Eifel. Studies on Rhine River terraces show that central parts of the Rhenish Massif have been uplifted by 140 to 250 m since 700-800 ka. These figures correspond to a very low long-term average uplift rate of 0.1-0.3 mm/a, which decrease to even lower rates towards the margins of the Rhenish Massif. There, conventional geomorphic analyses, such as K_SN values, Chi-maps and basin asymmetries, show no evidence of vertical motions.

Field observations in several valleys of the Diemel river catchment in the northeastern Rhenish Massif show steeper west-facing topographic slopes compared with flatter east-facing slopes, suggesting asymmetric bedrock incision due to ongoing surface uplift. We analysed topographic river profiles on a regional scale in five catchments (Möhne, Alme, Ruhr, Diemel and Eder) using 1 m-resolution Lidar data to see whether they are affected by asymmetric river incision Our results show that only the S-N oriented streams cutting into lithologically heterogeneous rock formations show asymmetric incision. This pattern resulted from uplift and tilting of the Rhenish Massif towards the NE, causing differential erosion.

These preliminary results will be substantiated by a more regional study comprising the entire margin of the Rhenish Massif. We aim to investigate whether the slow vertical surface movements around the Eifel Plume could have led to asymmetric bedrock incision elsewhere, too.

Fabrics in the granulites of the Saxonian Granulite Massive (SGM) are interpreted to result from deformation related to early exhumation at deep crustal conditions, followed by subsequent shearing of the granulite roof against lower grade country rocks at retrograde conditions by top-SE shearing (e.g Reinhardt & Kleemann, 1994). For structural evidence and establishment of the rheological implications of such a multiphase deformation within the felsic granulites, detailed structural fieldwork and thin section scale microstructural analyses were carried out.

In the central SGM we observed a mylonitic foliation defined by interlayered quartz ribbons (20 vol.-%) and a homogeneous Qtz-Kfs-Pl-matrix that is transposed by a second mylonitic foliation towards the SE-rim, simultaneous with boudinage and proportion reduction of quartz ribbon (6 vol-%), and growth of biotite in the polyphase matrix. A NE-trending stretching lineation progressively rotates towards a SSE-trend. Quartz in the Qtz-Kfs-Pl-(Bt)-matrix generally has no CPO. Quartz ribbon’s (0001) CPOs change from two orthogonal, peripheral maxima to a central maximum.

Transposition of the foliation and lineation results from a change in the kinematics of flow at progressively lower temperature conditions, supported by a change from <0001> to <11-20> easy slip in the ribbons. Nevertheless, due to the generally high volume percentage of the Qtz-Kfs-Pl-(Bt)-matrix we assume diffusion creep s.l. involving grain boundary sliding to be the dominant deformation mechanism in all felsic granulites, suggesting a dominant linear-viscous rheology during the exhumation path.

References

Reinhardt, J., & Kleemann, U. (1994). Tectonophysics 238, 71–94, https://doi.org/10.1016/0040-1951(94)90050-7

The King’s Trough Complex (KTC) is a major canyon-like structure in the eastern North Atlantic and consists of several deep basins: The huge King’s Trough in the west is flanked by elongated ridges, while at its eastern opening the smaller Peake and Freen Deeps are separated by the Palmer Ridge. The King’s Trough is located in an area of elevated seafloor covered with numerous seamounts, which transitions to the Mid-Atlantic Ridge (MAR) flank toward the west. Here we present major and trace element and Sr-Nd-Hf-Pb isotope data from submarine volcanic rock samples obtained during RV METEOR cruise M168.

Whereas lavas from the eastern deeps show N- and E-MORB signatures and moderately depleted isotope compositions, samples from the western King’s Trough and surrounding seamounts display predominantly enriched OIB-like compositions. This geographic transition would be consistent with involvement of a mantle plume that was located beneath or near the MAR resulting in elevated seafloor of relatively enriched geochemical composition. The troughs probably formed subsequently by rifting and/or transtension when (36 to 42 Ma) the KTC area represented a temporary plate boundary between the Iberian and Eurasian plates. In the east, the KTC cuts into older (not elevated) crust, presumably formed prior to plume-ridge interaction, explaining why samples obtained from there possesses normal to transitional MORB compositions. Age and further isotope data are pending and will reveal if the ridges on the King’s Trough flanks represent younger, plume-related excess volcanism or simply the tops of tilted graben shoulders along the former plate boundary.

The Pustertal-Gailtal Line (PGL) belongs to the dextrally transpressive Periadriatic Fault system and forms the border between Southern and Eastern Alps. Although part of the ongoing convergence between Adria and Europe appears to be accommodated by this fault system, it reveals little instrumental and historical seismicity. In our study, we attempted to find evidence for past seismic activity along the PGL by investigating pseudotachylite occurrences.

We investigated an area of c. 19 km² to either sides of the PGL around Maria Luggau (Austria). We identified cataclasites and fault gouges along the fault core zone, from which we investigated only the cohesive rocks. Cataclastic, foliated Oligocene granitoids as well as garnet-mica schists of the Austroalpine basement are crosscut by cm- to dm-scale veins containing black fault rocks, which were sampled for further analyses.

Polarisation microscopy reveals that the vein-forming black fault rocks are often optically isotropic, testifying to their origin as quenched melts. Sharp margins of mm- to cm-sized injection veins against the surrounding host rock, well-rounded quartz and feldspar clasts, the absence of hydrous minerals in the matrix, as well as spherulites are further hints at a seismogenic origin of the studied fabrics. Some of the optically isotropic veins are internally foliated; their in-situ µ-XRF analysis of major element concentrations revealed chemical composition variations in the foliation. Even if this foliation might suggest overprinting by aseismic creep, our observations indicate a seismogenic origin of the studied fabrics as pseudotachylites.

The Bathymetrists Seamounts (BSM) form a 900 km long and 200 km wide volcanic chain of about 40 volcanic edifices within the eastern Equatorial Segment of the Atlantic. They are located between the Vema Fracture Zone in the north and the 4°N Fracture zone in the south (both transcurrent faults). Like other submarine chains east of the Mid-Atlantic Ridge, the BSM trend NE-SW. Many of those volcanic chains are intensively studied and attributed to hot spot tracks above mantle plumes. However, the BSM is much broader and strongly associated with faults. Still, it remains unclear if a mantle plume, decompression melting along fracture zones, or small-scale upper mantle convection caused these seamounts. We present new insights to the BSM based on about 80,000 km² high-resolution bathymetric data with 50 m spatial resolution, and 4,000 km of 2D seismic reflection data, collected during expeditions RV Merian MSM70 in 2018 and RV Meteor M152/2 in 2019. Seismic sections across the volcanic edifices allow a simple estimation of their relative age distribution, as it is inferred by the stacking pattern of the volcanic successions. Moreover, the structural pattern includes flower structures and indicates transtension. The single seamounts are arranged along E-W to NE-SW lineaments that can be explained by large-scaling Riedel shears. This Riedel shear pattern reveals a NW-SE orientated extensional local stress field during its generation in the Paleogene. Therefore, deep mantle plumes and shallower tectonics on a lithospheric scale could play an important role in the emplacement of the volcanoes.

The Christiana-Santorini-Kolumbo volcanic field, in the Aegean Sea, has hosted more than 200 explosive eruptions in the past 360,000 years, including the 1650 eruption of Kolumbo Volcano. In this contribution, we use the first 3D seismic reflection data collected over the submarine Kolumbo Volcano to explore active faulting and its relationship to volcanism. The 3D data enable us to extract useful fault attributes (strike, dip, dip direction) which can be used to decipher local stress fields. Our results reveal clear NW-SE directed extension around the volcano, consistent with published focal mechanisms from microseismicity. The data also provide exceptional 3D imaging of the Kolumbo Fault Zone, which lies ~6 km northwest of Kolumbo Volcano. Interpreted horizons through the Kolumbo Fault Zone reveal distinct relay ramps between overstepping normal faults. We suggest that magma ascent within the fault zone likely exploits enhanced vertical permeability associated with distributed deformation within relay ramps. Further research is required to understand the range of scales over which relay ramps could affect crustal permeability, and by inference magma ascent, in the greater rift zone.

Abstract: Twinned calcite occurs in calcite-bearing metagranite cataclasites within crystalline megablocks of the Ries impact structure, Germany, as well as in cores from the FBN1973 research drilling. The calcite likely originates from pre-impact veins within the Variscan metagranites and gneisses, while the cataclasis is due to the Miocene impact. Quartz in the metagranite components does not contain planar deformation features, indicating low shock pressures (< 7 GPa). Calcite, however, shows a high density (> 1/µm) of twins with widths < 100 nm. Different types of twins (e-, f- and r-twins) crosscutting each other can occur in one grain. Interaction of r- and f-twins results in a-type domains characterized by a misorientation angle of 35-40° and a misorientation axis parallel to an a-axis relative to the host. Such a-type domains have not been recorded from deformed rocks in nature before. The high twin density and activation of different twin systems in one grain require high differential stresses (on the order of 1 GPa). Twinning of calcite at high differential stresses is consistent with deformation during impact cratering at relatively low shock pressure conditions. The twinned calcite microstructure can serve as a valuable indicator of high differential stresses and sufficient confining pressure to prevent brittle deformation. The stress conditions at relatively low shock pressures (< 7 GPa) during impact-cratering are comparable to those at hypocentral depths during seismic rupturing in the continental crust. Therefore, comparable high-stress crystal plasticity of calcite might likewise be expected from fault rocks deformed at hypocentral depths.

The Koralm Complex in eastern Austria comprises various gneisses and eclogite lenses which record high-pressure metamorphism of Late Cretaceous age, acquired in an intracontinental subduction zone. The mechanism of exhumation of the Koralm Complex is either slab extraction or wedge extrusion. The present study aims at adding structural evidence to this problem. We studied an WSW-ESE-striking shear zone with SSE-dipping foliation and subhorizontal stretching lineation in the central part of the Koralm Complex. Based on quartz crystallographic preferred orientations (CPO) in gneiss, Krohe (1987) demonstrated sinistral shearing in this shear zone. We investigate microstructure and CPO of samples from the same shear zone using electron backscatter diffraction and photometry. Microstructures indicate grain-boundary migration, subgrain rotation, and static annealing. We find sinistral as well as dextral shear sense. This may either reflect flattening in the shear zone or two phases of deformation with contrasting kinematics. These two possibilities are discussed based on the textural data.

References

Krohe, A., 1987. Kinematics of Cretaceous nappe tectonics in the Austroalpine basement of the Koralpe region (eastern Austria). Tectonophysics 136, 171–196. https://doi.org/10.1016/0040-1951(87)90024-2.

Slab fluids, which are released by the subducting oceanic lithosphere through compaction and dehydration processes, are an essential mechanism for the transfer of volatiles from the slab to the mantle wedge. However, migration processes of slab dehydration fluids are not well understood yet, particularly with regards to transport mechanisms of redox sensitive elements such as sulfur.

In this study we investigated an eclogite-facies metabasalt from the South Tianshan Orogen, NW China, which contains several omphacite-dominated HP veins. Using mineral chemical analyses combined with in situ δ³⁴S measurements of pyrite, as well as isotope analyses of C, O, Sr and Pb in mineral and vein separates, we determined the metamorphic evolution of the studied sample and the speciation of sulfur during fluid infiltration and transfer.

Mineral chemical and isotopic compositions reveal seafloor alteration, affecting the protolith pillow basalt prior to subduction. This was followed by a two stage intra-slab fluid-flow under peak to prograde metamorphic conditions, forming the omphacite-dominated HP-veins. The first HP fluid originated from dehydrating ocean floor basalts, as documented by MORB-like pyrite δ³⁴S signatures. The second HP fluid composition suggests, instead, an origin from the basalt-sediment transition with negative pyrite δ³⁴S values of about -10‰. Pathways formed by the first fluid were reused and enlarged by the second fluid, which however also formed new pathways. This sample provides detailed insights into intra-slab fluid flow and fluid-rock-interaction processes at HP/LT metamorphic conditions and allows a better understanding of fluid transfer and sulfur speciation in subduction zones.

The Liguro-Provençal Basin, situated at the junction of the Northern Apennines and the Western Alps, formed due to the rollback subduction of the Adriatic-African plate underneath Europe and the subsequent upper plate extension in the Oligocene to early Miocene time. The opening of this basin was accompanied by the counter-clockwise rotation of the Corsica-Sardinia block relative to Europe until 16 Ma, with the basin widening towards southwest. It is yet unclear if the extension ever reached seafloor spreading with the production of oceanic crust, or whether it led to anomalously thin continental crust and/or to mantle exhumation. Although considered as tectonically inactive today, the Liguro-Provençal Basin shows active seismicity, indicating compression and potential basin inversion. Thus, it is crucial to better understand the opening of the basin and the tectonic inheritance due to rifting in order to better interpret the present-day seismicity. To this end, we compile existing geological and geophysical data, including recent data from the 4DMB project (“Mountain Building Processes in Four Dimensions”), to constrain the crustal and sedimentary thicknesses throughout the basin. We also focus specifically on two profiles in the NE (Corsica-Provence) and SW (Sardinia-Gulf of Lion) parts of the basin and compare these with the results of coupled thermo-mechanical and surface process modelling using Aspect and Fastscape codes. Finally, we discuss the effect of differences in various parameters, such as pre-rift crustal thickness, rift velocities and sediment supply, on rifting processes in the Liguro-Provençal Basin.

One of the major tectonostratigraphic characteristics of foreland basins is the transition from deep marine (i.e. flysch) to terrestrial (i.e. molasse) depositional settings. Several mechanisms have been proposed to influence this flysch-to-molasse transition, including slab breakoff beneath the adjacent mountain range. However, this coupling has not yet been assessed quantitatively. We hypothesize that isostatic rebound following slab breakoff can lead to a spike in tectonic uplift of the orogen, resulting in increased sediment supply as well as uplift of the foreland basin, thereby causing shallowing.

This study aims at investigating whether slab breakoff leaves a stratigraphic fingerprint foreland basin stratigraphic architecture. To this end, we combine 2D geodynamic modelling of slab breakoff with Alpine-inspired rheologies with forward stratigraphic modelling using GPM (Geological Process Modelling) software. In this context, we extract subsidence and uplift velocities along 2D profiles during slab necking- breakoff to account for (1) fast/slow breakoff and (2) different slab bending angles. Second, the extracted velocity fields are used as input for creating forward stratigraphic models (FSM), in which eustatic sea level changes are introduced to test whether slab break-off has a first-order control on foreland basin sedimentation. Erosion, transport and deposition of sediments are modelled as diffusional processes (i.e. gravity driven).

Preliminary results indicate that a pulse in sediment supply corresponds to onset of slab necking whereas breakoff yields a small pulse instead. This could imply that already during necking the orogen is isostatically uplifted to such a degree that sediment supply towards to foreland basin increases significantly.

Major faults such as the Periadriatic Fault and the Giudicarie Fault have been active in the past, and they have even been central features of the larger-scale deformation in the Alps. It seems that these faults are not active anymore though and we investigate why this is so by inspecting the orientation of the regional stress field which loads the faults mechanically. The orientation of maximum horizontal compressive stress (SHmax) is commonly estimated from in-situ borehole breakouts and earthquake focal mechanisms. Borehole measurements are expensive, and therefore sparse, and earthquake measurements can only be made in regions with many well-characterized earthquakes. Here we derive the stress-field orientation using stress-induced anisotropy in nonlinear elasticity. We measure the strain derivative of velocity as a function of azimuth. We use a natural pump-probe approach which consists of measuring elastic wave speed using empirical Green’s functions (probe) at different points of the earth tidal strain cycle (pump). The approach is validated using a larger data set in the Northern Alpine Foreland region where the orientation of SHmax is known from borehole breakouts. The technique is then applied to the Southern Alps to understand the contemporary stress pattern associated with the ongoing deformation due to the counterclockwise rotation of the Adriatic plate with respect to the European plate. Our results explain why the two major faults in Northeastern Italy, the Giudicarie Fault and the Periadriatic Line (Pustertal-Gailtal Fault) are currently inactive, while the currently acting stress field allows faults in Slovenia to deform actively.

Anatomy and internal structure of the Alpine orogen are difficult to decipher as structural information is usually limited to surface and seismic data. Seismic results very much depend on the elastic wave velocity model of the rocks. Simple velocity models depend strongly on the rock composition. In the investigated rock samples, phyllosilicates are by far most decisive for the elastic anisotropy. We present here the first results of fabric analysis in a N-S profile of the Innsbruck quartzphyllite and the Bündner schist from the northern part of the Brenner Base Tunnel Project in order to obtain a refined anisotropy and velocity model.

Phyllosilicate-rich sections were selected from borehole and tunnel samples, from which 1.5 – 3.5 mm wide columns were drilled out from layers of different composition and structure. The CPO of phyllosilicates and graphite was measured using high energy X-ray diffraction at German Electron Synchrotron (DESY) and European Synchrotron Radiation Facility (ESRF). Pole figure data were directly extracted using single peak evaluation and compared to the optical microstructure and compositional distributions using µXRF measurements.

Texture strength is variable along the section with peak values at the transition from the Innsbruck quartzphyllite to the upper Bündner schist. The texture strength correlates positively with the content and distribution of phyllosilicates and graphite. By measuring the smallest representative volume element, we estimate the upper bound of expected intrinsic velocity anisotropies. The effect of (micro)structure-based upscaling on these anisotropies will be discussed.

Detailed crustal structures and causative kinematic processes in the Alps continue to be a matter of ongoing research. Of particular interest is the crustal structure of the Adriatic indenter, the northern tip of the Adriatic plate that collided with and significantly deformed the Eastern Alpine Orogen in the Oligo-Miocene.

As part of the “Mountain Building in 4D” (4DMB/AlpArray) project, a high-density network of seismic stations was previously used to produce 3-D models of compressional wave velocity (Vp) of the crust and upper mantle in the Eastern and eastern Southern Alps using Local Earthquake Tomography (LET). This LET model shows a thickened high velocity zone within the lower crust beneath the Periadriatic fault, which is expected to relate to the local gravity field variations.

Here, we present results of gravity modelling using the IGMAS+ software and densities derived from the P-wave velocities of the LET model. Different possible empirical relationships between Vp and density are explored and compared to previous models as well as the AlpArray Gravity measurements to further constrain the present lithological and tectonic structures in the Eastern and eastern-Southern Alps. Strengths and weaknesses of the LET model and the gravity response of the derived densities, in particular regarding uncertainties of structures at greater depths, will be discussed.

We present ¹⁰Be-derived denudation rates from modern (n = 54) and buried sediment dated to 2.0–2.7 Ma (n = 3), and exhumation rates derived from published apatite fission track (AFT; n = 296) and apatite (U-Th-Sm)/He (AHe; n = 125) thermochronology from the Kyrgyz Tian Shan. Modern ¹⁰Be denudation rates are generally higher than the long-term AFT and AHe exhumation rates. On average, the highest ¹⁰Be denudation rates are recorded in the Terskey range, south of Lake Issyk-Kul. Here, ¹⁰Be-derived denudation rates from 2.0–2.7 Ma are comparable in magnitude with the AFT- and AHe-derived long-term exhumation rates, but modern ¹⁰Be-derived denudation rates are higher. We propose that denudation in the Kyrgyz Tian Shan, particularly in the Terskey range, remained relatively steady during the Neogene and early Pleistocene and increased after the onset and intensification of the Northern Hemisphere glaciations at 2.7 Ma due to glacial-interglacial cycles. Comparison with published data from the Pamir–Tian Shan region shows a spatial trend of decreasing modern denudation rates from west to east and an increase in the difference in magnitude between long-term exhumation rates and modern ¹⁰Be-derived denudation rates, suggesting that deformation controls denudation in the Pamir and Western Tian Shan, while farther east, the denudational response of the landscape to Quaternary glaciations becomes detectable by ¹⁰Be. We also find moderate correlations between modern denudation rates and topographic metrics and weak correlation between denudation rate and annual rainfall, highlighting complex linkages among tectonics, climate, and surface processes that vary locally.

The evolution and course of Himalayan rivers when exiting the orogen is controlled by the interplay between tectonics, climate, and associated sediment flux. We investigate these interactions by studying a Late Pleistocene deflection of the Sutlej River at the southern margin of the western Himalayan. This part of the Himalaya is also referred to as Kangra Recess. Late Quaternary faulting and folding along the Main Frontal Thrust and related back thrusts has created anticlinal structures in the south and piggyback basins in the north. Combined field observations and chronological constraints have shown that the anticline evolved as multiple fault segments, which grew through lateral propagation and led to the permanent deflection of the Sutlej River by ~ 50 km to the southeast. In this work, we present new luminescence and cosmogenic nuclide chronologies combined with previously published data to better identify the sedimentation history. Most importantly, we focus on the cause and final timing of the permanent river deflection. We show evidence for widespread aggradation and sediment deposition by the Sutlej River megafan and its tributaries starting before 47 ka and continuing until ~ 26 ka. Our 10Be and 26Al results in combination with available OSL data document the last widespread throughflow of the Sutlej at ~ 30-25 ka. We argue that a combination of climate and tectonic factors, especially
the variability of monsoonal strength, led to major changes in sediment supply at short time scales and therefore affected the course of the Sutlej River system.

The Himalaya is the highest and steepest mountain range on Earth and forms today efficient north-south barrier for moisture-bearing winds. 1D-thermokinematic modeling of new zircon (U-Th)/He bedrock-cooling ages and >100 previously published mica ⁴⁰Ar/³⁹Ar, zircon and apatite fission track ages from the Sutlej Valley document a consistent rapid decrease in exhumation rates that initiated at ~17-15 Ma across the entire Greater and Tethyan Himalaya and the north-Himalayan Leo Pargil dome. We observe a rapid decrease from >1 km/Myr to <0.5 km/Myr. We explain the middle Miocene deceleration of exhumation with major tectonic reorganization of the Himalayan orogen, probably coincident with the onset of basal accretion, which resulted in accelerated uplift of the Greater and Tethyan Himalaya. The period of slow exhumation in the upper Sutlej Valley coincides with a period of internal drainage in the south-Tibetan Zada Basin farther upstream, which we interpret to be a consequence of tectonic damming. Comparison with other data from the Himalaya and Southern Tibet along strike suggests that by ~15 Ma, southern Tibet was high, located in the rain shadow of the High Himalaya and eroding slowly for at least 10 Ma, before erosion accelerated again by ~5-3 Ma, most likely due to climatic changes. Our new finding document that the location of tectonic deformation processes controls the first order spatial pattern of both climatic zones and erosion across the orogen. Therefore, we think that the rise of Greater Himalaya is linked to the deceleration of exhumation in Southern Tibet.

Most islands host an endemic biota, i.e., present nowhere else on Earth. This is the case, for instance, of Madagascar. It has been shown that different populations of lemurs, endemic to the island, are mostly distributed along the watersheds surrounding Madagascar, creating a so-called micro-endemism, while the populations living on the high-elevated watersheds, on the central plateau, are not showing this micro-endemism. Here we wish to address the question whether there exists a correlation between the evolution of the landforms (i.e., the geometry of the watersheds) of Madagascar and the hybrid evolution of lemur populations? More broadly, can the tectono-geomorphic evolution of an island be advantageous or disadvantageous to the flourishing of micro-biodiversity?

To answer these questions in a quantitative manner, we combined a Landscape Evolution Model based on the Stream Power Law and taking into account flexural isostasy, with a speciation model. We first developed a morphometric index to differentiate between islands with a central plateau surrounded by smaller basins, like Madagascar, from conical islands, like Sri Lanka. We then predicted patterns of biodiversity as a function of the index value and its time evolution. We show that for the tectono-geomorphic evolution to influence patterns of biodiversity requires a specific range of model parameter values, in particular the parameters characterising dispersal and mutation. We finally used phylogenetic observations to constrain some of these parameters.

Changing climatic conditions cause alluvial rivers to aggrade and incise, which can result in the formation of multi-generational fluvial terrace sequences. Such records can be used to investigate past interactions between climatic conditions and the fluvial system and to predict channel responses to future climatic change. To accurately assess such interactions, precise dating of terrace sequences is vital. However, established methods such as ¹⁰Be exposure dating are costly and time intensive. Thus, they are impractical for application to spatially extensive areas and for establishing patterns of along-stream aggradation or incision.

An alternative approach of dating fluvial terraces is based on the degradation of the slope (riser) between successive terraces by down-slope sediment transport. Here we present a tool for analyzing high-resolution elevation profiles across alluvial terrace risers and inferring their age since abandonment, based on linear and nonlinear hillslope diffusion models. We extend this workflow to the analysis of DEM-derived riser profiles that can provide a greater spatial extent and resolution than GNSS profiles or exposure ages. A set of ¹⁰Be exposure ages dating back to ca. 1 Myr from terraces around the Río Santa Cruz, Patagonia is used for calibration and to test the method’s viability. Preliminary results highlight the importance of post-abandonment riser disturbances and variability in hillslope sediment-transport rates.

This technique provides a low-cost, spatially extendable way of dating fluvial terraces and analyzing landscape dynamics in fluvial systems. We are currently preparing to release an open-source Python package for performing these analyses.

Slab break-off is a geodynamic process in which the lower portion of a subducting plate detaches from its uppermost one. This process changes the force balance acting on the lithosphere causing tectonic uplift that can affect the sedimentary basin architecture by reducing the accommodation space and increasing the sediment supply due to source rejuvenation. While sediment supply intensity is commonly attributed to tectonic and/or climatic factors, recent studies have highlighted that the erodibility of the source area can have a significant effect on the timing of these signals.
To investigate this hypothesis, we modify the stratigraphic forward modeling software GPM (Geological Process Modeling software provided and produced by SLB), to consider the impact of topography-dependent steady flow. The simulation involved clastic deposition in a deltaic environment and included variations in source area erodibility, sea level changes, tectonic rates, and variable water discharge. Simulations were conducted with increasing complexity to quantify the sensitivity of catchment scale depositional rates to the aforementioned changes.

Southern Patagonia hosts uniquely well-preserved fluvial cut-and-fill terraces, formed along rivers fed by glacial meltwater, recording the onset of a regional phase of net incision. However, the timing and driving mechanism of incision remain debated. Published thermochronometric dating and modelling suggest increased exhumation in the last 1–3 Myr. Radiometrically dated basalt flows establish the existence of a eastward-draining paleo-valley with flows going existing terraces by 3.2 Ma. To better constrain the timing of Pleistocene river incision and landscape evolution in southern Patagonia, we present new cosmogenic ¹⁰Be exposure ages of terraces near Tres Lagos and the upstream reaches of the Río Santa Cruz (50ºS). Preliminary terrace surface exposure ages at Tres Lagos are between 70 ka–1.02 Ma, whereas upstream Río Santa Cruz terraces are between 390 ka and 1.04 Ma. The terrace age sequence shows that a phase of net incision started ~1 Myr after the widespread emplacement of basalts, concomitant with enhanced climatic forcing following the Mid-Pleistocene Transition. Our new exposure ages are in agreement with dated fluvial terraces of other Patagonian rivers, where ages range from 400 ka–1 Ma (47ºS; Tobal et al., 2021). Moreover, our record of Pleistocene landscape evolution is similar to other records throughout the Andes, where the timing of fluvial incision has been linked to enhanced climatic forcing after ~1 Ma. Our results point to a strong influence of the Mid-Pleistocene Transition on landscape evolution at a continental scale, notably including southernmost South America.

The measurement of ^239,240Pu in environmental samples can play a key role in investigating Anthropocene Earth (sub-)surface processes. As a consequence of atmospheric nuclear weapon tests conducted in the 1950s and 1960s, Earth’s outermost skin was supplied with fallout radionuclides (FRNs), providing distinct geochronological markers. The application of FRNs is well established, with ¹³⁷Cs being most commonly measured. However, ^239+240Pu activities are more decay-insensitive (t_1/2 ²³⁹Pu: ~24.1 ka; ²⁴⁰Pu: ~6.6 ka), there is less soil inventory contamination arising from nuclear power plant accidents than reported for ¹³⁷Cs, and only a few grams of sample material can be sufficient for a measurement. Ultimately, the (separate) quantification of ^239,240Pu inventories measured by Accelerator Mass Spectrometry (AMS) represents a further evolution step towards more precise measurements than achieved by other mass spectrometry or decay counting techniques.

The development of ^239,240Pu measurement capabilities at the Centre for Accelerator Mass Spectrometry (CologneAMS), University of Cologne (UoC), has given the go-ahead to exploit the wealth of possible ^239+240Pu applications to decipher modern Earth (sub-)surface processes in different settings. Based on tailored sample processing protocols applied at the Institute of Geology and Mineralogy and the Division of Nuclear Chemistry (both UoC), we present first results from a selection of ongoing projects. The sample processing workflow applied together with the AMS measurement precision achieved allows for resolving specific activities below ~5 mBq kg^-1. Accordingly, a spatial focus is laid on study sites where ultra-high precision of measurements is required (e.g., the Atacama Desert in northern Chile).

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The weathering of silicate rocks removes CO₂ from the atmosphere-ocean system on geological timescales but the time required for weathering intensity to respond to changes in climate is poorly constrained. The radiogenic isotopes of hafnium and neodymium are decoupled during silicate weathering with the isotopic composition of river clays being offset from bulk rocks. Here we examine the decoupled Nd-Hf isotopes of clays deposited in marine sediments from the northern Bay of Bengal near the mouth of the Ganga-Brahmaputra rivers. The sediment core (SO188 17286-1) covers the last 130 kyrs and has been used to study the past intensity of the South Asian Monsoon (SAM). The deviation of the Hf isotope compositions from the array defined by global river clays (ΔεHf clay), has a pattern of variability similar to the record of SAM intensity inferred from the reconstructed δ¹⁸O of seawater and δD of leaf waxes. These variations in silicate weathering intensity occur on timescales near 20 kyrs and appear to be paced by orbital precession. This suggests a strong, and rapid (on geological timescales), link between SAM hydroclimate and silicate weathering in this region. In contrast, changes in the source provenance of the clays as recorded by their Nd isotope signatures follow a glacial-interglacial pattern indicating either a sea level or global climate influence on changes in sediment transport to the shelf. This contrast demonstrates the great utility of ΔεHf clay to record changes in weathering intensity while directly accounting for shifts in sediment source provenance.

The deep Southern Ocean (SO) circulation is of major significance for understanding of the ocean´s impact on Earth’s climate as uptake and release of CO_­­­2 strongly depend on the redistribution of differently ventilated water masses.

Here, we present new authigenic neodymium isotope data (εNd) of the deep-sea sediment ODP1093 in the Southern Atlantic that reveals several systematic temporal glacial-interglacial changes in a range of 6.3 e-units. Assuming Nd-isotopes as mostly conservative tracer and neglecting possible reginal influences, the observed radiogenic εNd values of up to -2.5 during peak glacial periods suggest a predominance of glacial PDW at depths of >3 km. This results in a volume increase of carbon-rich water, aiding in atmospheric CO₂ drawdown during glacials.

The ability of εNd to trace water mass changes relies on the sensitivity of water masses to conservative Nd-isotope mixing. The εNd gradient ΔεNd is here defined as the North-South difference in εNd/10° latitude and is a measure for the sensitivity to changes in εNd signature over a given distance. Compared to further existing εNd records across the Atlantic Ocean the calculated mean εNd gradient for the Atlantic Ocean is approximately 0.89 ε-units/10° latitude and the εNd values of ODP1093 are constantly the most radiogenic. This suggests, that changes in ocean circulation during glacial-interglacial transitions are not purely induced by the Northern Hemisphere deep convection and southward flow but rather strongly influenced by equally strong changes of the SO circulation. This reinforces the importance of the SO in past and future climate changes.

In this contribution, we discuss our latest results from the project “Deformation Mechanisms along the Main Marmara Fault (DEMMAF)”, funded by the ICDP priority program of the German Science Foundation. The Main Marmara Fault (MMF), is the northern branch of the North Anatolian Fault along the Marmara Sea (NW Turkey). The MMF has produced several major earthquakes (M7+) in the past with a recurrence of about 250 years, and has not ruptured since 1766. The goal of the DEMMAF project is to investigate what controls the deformation mechanisms along the MMF, using data collected at the ICDP GONAF observatory (Geophysical Observatory at the North Anatolian Fault) and a combined work flow of data integration and process modelling approach.

Here, we use a forward numerical approach that implements frictional faults and visco-elastic off-fault materials to investigate the space- and time-scales of the long-term seismic behavior of the Main Marmara Faults and its main controlling factors. The MMF is modelled following a Coulomb frictional constitutive law and the spatially variable off-fault rock properties are derived from a data-integrative lithospheric-scale 3D structural model of the region around the MMF. The forward model is used to test the effect of varying boundary conditions (i.e. kinematic) and fault strength properties (i.e. coefficient of friction). Our modelling approach highlights the first order role of crustal rheology and fault-strength in the long-term behavior of the MMF (spatial distribution and recurrence of seismic events), as well as their potential to explain the along fault locking degree variability.

The erosive convergent plate margin offshore Costa Rica represents a seismic zone that produces high-magnitude earthquakes and tsunamis. The overriding Caribbean Plate is tectonically eroded by the subducting Cocos Plate, resulting in strong and widespread deformation of the upper plate. Differences in composition, compaction or deformation of the clay-rich marine sediments can have a significant impact on the strength of the continental plate, as well as the frictional behavior of the rocks entering the subduction channel.

Core samples from IODP Expeditions 334 and 344 of the Costa Rica Seismogenesis Project (CRISP) recovered from a depth range of 5–125 mbsf were experimentally deformed in triaxial tests under isotropic consolidated and undrained conditions at confining pressures of 400–900 kPa, room temperature, axial displacement rates of 0.0025–0.01 mm/min and up to ~50% axial compressive strain. Deviatoric stresses range between 127 and 418 kPa, pore pressure between 615 and 822 kPa. The samples exhibit internal friction angles of 8-42° and cohesion values of about 29-34 kPa.

The stress-strain records show exclusively structurally weak behavior and a higher consolidation of the upper plate compared to the incoming plate sediments. The sediments from prism toe and middle slope of the Caribbean Plate display systematically higher peak stresses despite a similar overburden. This together with the consolidation state indicate a loss of overburden, for example due to slumping at the continental slope. The mechanical properties might be crucial for fracturing and localized brittle deformation of the continental forearc during tectonic erosion.

As the world warms due to rising greenhouse gas concentrations, the Earth system moves toward climate sthistoricalhout historic precedent, challenging societal adaptation. One way to investigate these unprecedented conditions is to study past climates and ecosystems that share similarities to our current and future ones. One such period is the Eocene (~56 – 33 Ma), during which the climate changed from a hot-house to a greenhouse state, comprising a wide range of atmospheric CO2 concentrations. However, our knowledge of the Eocene climate evolution is incomplete because of a lack of terrestrial records covering the entire period. To address this gap in our understanding, we propose to obtain drill cores at Geiseltal in Eastern Germany.

This former lignite quarry is famous for its exceptionally well-preserved Eocene m. Still, itssils, but its potential as a climate archive has not yet been explored due to the lack of existing drill cores. By drilling a maximum of three cores, we aim to create a spliced 100-120 m long record comprising the entire Eocene archived in Geiseltal as an alteration of lignite seems intercalated with fluvial strata. High-resolution, multi-proxy analyses of the obtained sediments will allow the generation of a unique record of (sub)orbital climate variability under various atmospheric greenhouse gas concentrations. To advance this project, we welcome scientific input from a wide range of disciplines (e.g., stratigraphy, sedimentology, paleolimnology, paleobotany, paleontology, and organic/inorganic geochemistry) as well as are actively seeking interested groups and individuals to collaborate with us on this project.

Lake Bosumtwi, formed after a meteorite impact at ~1.07 Ma, contains a sedimentary archive that yields an excellent high-resolution record of climate- and environmental change in Sub-Saharan West Africa. The region is highly susceptible to climate changes due to shifts of the tropical rain belt and variation in dust dynamics in the tension field between the North African Monsoon (humid, wet) and the Harmattan (dry and dusty winds from the Sahara). Consequently, Lake Bosumtwi has been intensively studied and in 2004, supported by the International Continental Scientific Drilling Program (ICDP), sediment cores were recovered and downhole logs were performed that allow for the analysis of the complete ~300 m lacustrine sequence. However, detailed climatic and environmental reconstructions for the record are incomplete, mostly due to the absence of a robust age model prior to 500 ka. In 2022, we conducted core scanning natural gamma ray measurements for the ~300 m lacustrine sedimentary sequence. Based on the resulting data, we are generating a correlative age model that is tested by cyclostratigraphic tools and that can be directly compared to the available independently dated sections, but extends farther back in time. Our age model will provide critical chronologic context for the numerous existing and new proxy data that facilitate a study of changes in climate, environment, and ecosystems. This will allow a robust framework to analyse climatic interferences with archaeological findings that might shed new light on habitat availability for our ancestors in tropical Western Africa.

Ferruginous conditions prevailed in the oceans through much of Earth’s history. However, past biogeochemical cycling inferred from mineral components identified in ancient iron formations remain poorly understood in terms of microbial processes prior to lithification. In Lake Towuti, Indonesia, ferruginous sediments sink through a stratified water column and are deposited under anoxic conditions that mimic the Earth’s early oceans, thereby allowing the study of both geochemical conditions in pore waters and long-term diagenetic evolution of its 1 Ma stratigraphic record.

We combined detailed pore water geochemistry and stratigraphic proxies with scanning electron microscopy imaging of authigenic phases. Although variability in elemental profiles attests to climate- and tectonic-driven processes along the 100-m-long sediment sequence, deposition of ferruginous minerals appears transient as particulate iron, reworked from surrounding lateritic soils, undergoes partial dissolution-precipitation during sinking and after burial. Minerals found to form in situ included magnetite (Fe₃O₄), millerite (NiS), siderite (FeCO₃) and vivianite (Fe₃[PO₄]₂ ∙ 8H₂O). Acicular millerite aggregates overgrown by siderite and vivianite indicate that they directly precipitated from saturated pore waters (Ostwald ripening). This also suggests that these mineral phases may constitute a diagenetic sequence stemming from the progressive consumption of terminal electron acceptors with sediment organic matter remineralization during shallow burial. Thus, we consider that these minerals act as biosignatures of redox processes driven by autochthonous sedimentary microbial populations that actively control pore water geochemistry after deposition, thereby differentially imprinting the stratigraphy of bulk sediment during burial.

To investigate the interior structure, dynamics and evolution of terrestrial planets, numerical models of varying complexity have become an essential tool for many researchers. Modelers often struggle with outreach and accessibility, especially when the demographic includes students and scientists who are less versed in programming and modeling. To provide easily available teaching material, we have compiled a collection of several codes developed at our institution.

Firstly, we present an updated Version of the code CHIC, which is a collection of applications, spanning 1D parameterized interior structure and thermal-evolution models to 3D thermo-chemical convection models. The code will now be published under an open-source software license. The release will include an updated documentation of the code. Once released, we plan to update the codebases, if sufficiently impactful changes have been implemented.

Furthermore, we will release multiple Python codes, mainly as teaching material. These will include models of:

- Tidal heat dissipation, for variable planetary systems.

- Interior structure in 1D, based on the planet’s properties.

- Thermal evolution in 1D, based on interior structure and tectonic regime.

- Simplified 2D thermal convection with temperature- and pressure-dependent viscosity.

Instructions on installation, application and evaluation, are presented in short tutorials. We also provide several educational examples and showcases of common benchmarks. The goal is to create a framework for our institute to publish software related to modeling of planetary interiors. The demographic includes students, teachers and scientists, as the codes range from educational material to advanced scientific models.

Currently, no search engine is available for specific and easy searches of published research datasets stored in institutional repositories. Most commonly, primary research data in institutional repositories are accessed via its Digital Object Identifier (DOI), which must be known.

The global findability of research data can be increased by mapping its metadata to a search tool that allows finding and accessing information from a single search point. For this purpose, we mapped the TRR170-DB planetary data repository (https://planetary-data-portal.org/) with its XML metadata to the search engine PRIMO via the OAI-PMH method. PRIMO is the central search interface of Freie Universität Berlin for searching and accessing local and external resources. Metadata mapped to PRIMO can be found by global search engines such as Google.

Data in the TRR170-DB repository reflect the different methods and approaches applied to investigate planet formation in the collaborative research center ‘Late Accretion onto Terrestrial Planets’ (TRR 170). Datasets are stored in open electronic formats such as csv (tables), pdf (text), and jpeg and tiff (images). Once a dataset is published, the repository guarantees archival and long-term access to the dataset with a DOI persistent identifier. At present, most datasets are in the public domain and represent replication data of peer-reviewed articles which appeared in international journals since 2016. PRIMO’s harvesting of TRR170-DB metadata ensures that the datasets remain easily accessible to the global community in the long term while providing a setting that amplifies the use of best practices and collaborative and interdisciplinary research.

The mission of the Helmholtz Metadata Collaboration (HMC, https://helmholtz-metadaten.de/en) is to facilitate the discovery, access, machine readability, and reuse of research data of the Helmholtz Association. Concepts and services are developed and established, allowing the enrichment of research data with standardized metadata in the various phases of their creation. The aim of HMC is to co-ordinate these services with the national and international scientific community in order to establish widely accepted practices in the handling of research data.

In the Earth and Environment Hub, we are in the process of setting up a transparent virtual round table where all communities can come together to decide which guidelines are recommended for the Helmholtz Association. Jointly agreed principles are discussed and agreed in a moderated co-design process.

Primary stakeholder profile

• Infrastructures – leadership, technical personnel organising, standardising, and sharing their (meta)data
• Data stewardship teams - these include personnel working for infrastructures, libraries, or thematic (meta)data management solutions/services
• Personnel in research groups working to standardise and curate (meta)data

In this presentation we will introduce to the current HMC activities and outcome: Our process for developing a guideline is planned as a coordinated procedure. For every single implementation guide, we go through the same questions, up to tests - based on use cases and definition of abstract test classes, in order to be able to validate the implementation. Our planned results are recommendations and detailed implementation instructions that enable interoperability - not only in the Helmholtz Association, but also in national and international communities.

The seismic wave velocity configuration of the mantle provides constraints on its thermal and hence density structure, although the proposed methods of wave velocity conversion differ significantly. The V2RhoT_gibbs is a Python tool that allows converting mantle seismic velocities to temperature and density using a Gibbs free energy minimization algorithm applied to a defined mantle chemical composition to guarantee thermodynamic stability of the correspondingpressure (P) and temperature (T) dependent phase and mineral assemblages. Alternative methods, in contrast, start the conversion process with a pre-defined, P and T independent mineralogical composition, while yet other conversion methods involve a set of empirical equations. To better understand the differences between these conversion approaches, we have applied different methods to a shear-wave velocity tomographic model of the mantle below the South China Sea region. The resulting thermal fields are compared regarding the depth of the 1300 °C-isotherm which is a proxy of the lithosphere-asthenosphere boundary. In addition, we present the conversion results in terms of their respective gravity responses. This sensitivity analysis has important implications for better understanding the thermomechanical state of the lithosphere in the region.

The deep thermal field in the continental lithosphere varies significantly depending on the age of the lithosphere, its tectonic setting and the time since the last tectonic event. Accordingly, orogens with a thickened radiogenic crust will be hotter in their crust than cratonic areas that had billions of years time to equilibrate after the last tectonic event. Areas affected by continental rifting and passive margins also may be characterized by specific lithospheric configurations and a distinct geothermal fingerprint. Using data-integrated models of different continental areas we evaluate the first-order controlling factors of the related threedimensional temperature distributions. We find that the resolution of subsurface heterogeneities and the consideration of the appropriate heat transport mechanisms are key in predicting the characteristics of the deep thermal field. Accordingly, the superposed effects of varying thermal conductivities, contributions of radiogenic heat and variations of the thermal lithosphere thickness together result in setting-specific background 3D thermal fields. These effects are superposed by the effects of coupled fluid and heat transport in the the upper few km of the crust. Knowing the first-order characteristics of the local thermal fingerprint is key for geothermal exploration but also for estimating the expected mechanical thickness as well as the nature and magnitude of seismicity.

Earthquakes are a direct response to the Earth’s state of stress, which is one of the key ingredients controlling the lithosphere rheological behavior. To first order, the total in-situ stress is a function of two main co-players: the long-term tectonic stress, and the short-term (seismic cycle) stress transfer. Despite their diversity in temporal and spatial scales, these components are not mutually independent, but they do interact in the final rheological configuration of the lithosphere

Understanding the relative importance of different tectonic loads and how the stress is transferred is of high relevance for robust earthquake simulators. As the stress transferred to a fault affects its mechanical behavior, it has a direct control on its potential to generate earthquakes.

Recent studies suggest that the regional tectonic environment surrounding the faults (e.g., off-fault lithology, lithospheric structure, and degree of coupling between crustal and mantle domains) can influence fault behavior. However, the importance of such heterogeneities in modulating background seismicity needs to be properly evaluated to unveil the behavior of these complex systems.

3D data-integrative and gravity-consistent models are useful tools for characterizing such lithospheric-scale heterogeneities, and ultimately, to analyze their potential relationship with background seismicity. In this contribution, we present the preliminary results of a 3D lithospheric model of the southern San Andreas Fault system, where the wealth of available data was considered. We demonstrate that this is an important step towards the calculation of the background off fault stresses due to local loadings, which likely influence background seismicity.

Seismic tomography provides important data to understand the physical properties (temperature, density) of the lithosphere and upper mantle. These physical properties are crucial for understanding e.g., strain localization, geothermal potential. However, interpreting tomography models in terms of composition and temperature conditions is highly complex and non-unique. There are mainly two approaches to interpreting seismic tomography models: empirical and thermodynamics-based. In the empirical approach, the tomography models are calibrated with respect to known temperature distributions, such as those derived from age-dependent oceanic lithospheric thickness or heat flow models or temperatures derived from mantle xenoliths in the continental regions. In contrast, the thermodynamics-based approach involves taking into account the composition of the minerals or deriving it from bulk-rock chemical composition using Gibbs-free energy minimization. Recently, a new approach has emerged that combines the second approach with geophysical (potential fields, topography) and seismological data (surface wave dispersion curves). However, this method assumes a steady-state temperature distribution, limiting its ability to infer the second-order temperature and density distribution. To address these challenges, a new thermodynamics-based conversion tool called V2RhoT_gibbs has been developed. This tool is based on open-source Python libraries and coupled with the Gibbs-free energy minimization algorithm Perple_X. It does not assume any thermal state and, using bulk-average chemical composition, derives the temperature and density distribution. Output from this tool could be easily used to incorporate e.g., as voxel in gravity field interpretations, or as lower temperature boundary condition to compute the thermal field.

Throughout history, humans have modified the landscape by farming, extracting natural resources, and deforestation. However, it is not fully understood to what extent such activities have changed vegetation structures and potentially caused accelerated soil erosion. In this study, we investigate the effects of human activities on vegetation and erosion rate changes on the island of Elba, Italy. Previous geoarchaeological studies succeeded in reconstructing human-environmental interaction in the past and providing an independent reference frame for the current study. Hence, we hypothesize that intense iron production on Elba since the 6th century BCE, first by Etruscans, and later by Romans, was accompanied by deforestation and thereby caused increased soil erosion. To test our hypothesis, we collected sediment samples from modern streams and from existing floodplain sediment cores to reconstruct the millennial-scale and more recent changes in landscape-scale erosion rates, and in vegetation and hydrology by means of leaf wax isotopes (d²H, d¹³C). We use in situ cosmogenic ¹⁰Be and ¹⁴C produced in quartz to obtain erosion rates. The different half-life of these two nuclides (~1.4 Myr for ¹⁰Be and ~5.7 kyr for ¹⁴C) makes them sensitive to changes in erosion rates that occur on human time scales. ¹⁰Be results indicate relatively uniform millennial-scale erosion rates on the order of 0.04 mm/yr across the eastern part of the island, where we collected most of the samples. We expect that the combination of these methods will reveal the impact and patterns of human-induced soil erosion in Elba.

Rock art is a common cultural manifestation throughout Colombia. Here the Painted Stone of Aipe represents a striking archaeological evidence as an outstanding masterpiece of pre-Hispanic rock art. Several pectorals of different shapes are observed as a central motif used by the pre-Hispanic communities of Quimbaya, Tairona and the southern tribes. In addition to the pectorals, the stylized devil or monkey is seen in various combinations along with nose rings, fishhooks, bead necklaces, pendants, and rattles, among others. The substrate of the Aipe Painted Stone is a yellowish sandstone of oval shape and the low-relieve carvings are mainly on the longer SE-side of the stone block. This study aims to assess the different decay phenomena affecting the ~500-year old pre-Hispanic rock art carved on the sandstone block which is at an altitude of 370m on a main road near the Magdalena River. The artwork has important conservation problems mainly due to weathering creating a complex set of mechanical, chemical and biological processes on the rock. In the sandstone, the ~0,1 mm quartz-grains (45%) and foraminifers (15%) are mainly cemented by cryptocrystalline SiO₂; also phases like phosphates, clays, micas, opaques and a high open porosity of 15 % occur, enhancing chemical dissolution and precipitation of Fe-oxides. Among the main identified deterioration agents are water flows and humidity changes, solar radiation, abrasion caused by dust and sand carried by the often strong wind, internal pressure variations due to temperature variations and salt migration, plants and microorganisms, but also anthropic interventions.

In late 2020, an approximately 650 m long core was drilled at Prees within the Cheshire Basin, England, as part of the ICDP project JET (Integrated Understanding of the Early Jurassic Earth System and Timescale). The main objective of this project is to obtain a complete and continuous sedimentary archive of the Early Jurassic. The Early Jurassic (~200-175 million years) was a period of extreme environmental changes, which will serve as an analogue for present and future environmental change. The project aims to provide a reference record for an integrated stratigraphy (bio-, cyclo-, chemo- and magnetostratigraphy) of this period.

Analysis of geophysical borehole logs will allow the description of sedimentary cycles related to orbital parameters and paleoclimatic history if depositional environment and sedimentation rate permits. Here, downhole logging data from the Prees-2 borehole are used to construct a floating astronomical timescale for the Sinemurian stage, contributing to an integrated timescale for the Early Jurassic. Cyclostratigraphic methods, including a statistical and a visual approach, lead to preliminary durations for the Sinemurian stage of ~6.2 and 6.8 million years, respectively.

The last of a total of three main subsidence episodes of the northern Upper Rhine Graben took place during the Pliocene to Quaternary and allowed the accumulation of thick sedimentary sequences that can function as excellent data source for paleoclimate reconstructions. A 323 m long sediment core drilled in 2020-2021 near Riedstadt-Erfelden (~14 km WSW of Darmstadt) is therefore likely a high-resolution geoarchive documenting climate dynamics during the Plio-Pleistocene epochs. However, so far, the chronostratigraphic framework is based only on lithostratigraphic assignments. This study presents inclination values and magnetic susceptibility obtained from whole-core measurements and discusses initial stratigraphic ideas based on the resulting preliminary magnetic polarity stratigraphy and cyclostratigraphic assessments of the ‘Riedstadt-Erfelden’ core. Our results will be used to study the completeness of the geological record and will enable comparisons to be made with the cores investigated through the Heidelberg Drilling Project. Our aim is to verify the suitability and significance of the ‘Riedstadt-Erfelden’ core as geoarchive for Plio-Pleistocene climate dynamics in Central Europe.