Conference Agenda

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Session Overview
Session
Poster Session on Monday (themes: 1.3, 2, 3, 4, 6, 7, 9, 11)
Time:
Monday, 12/Sept/2022:
5:00pm - 6:00pm

Location: Hörsaal G // Hörsaal F


Hörsaal G l Poster 1 - 35

Hörsaal F l Poster 36 - 73


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Presentations
MON: 1
Topics: 1.3 Bridging length and time scales in the modelling of geomaterials

Adsorption of the drug molecule carbamazepine in zeolites: Studying host-guest and guest-guest interactions with DFT calculations

Michael Fischer

University of Bremen, Germany

In the past two decades, pharmaceuticals and personal care products (PPCPs) have been identified as environmental contaminants of considerable concern due to their significant hazard potential. The anticonvulsant drug carbamazepine (CBZ, C15H12N2O), widely prescribed in the treatment of epilepsy, is a particularly relevant PPCP contaminant: It is hardly removed by conventional wastewater treatment techniques, shows considerable persistence in environmental waters, and negatively affects different organisms. Currently, various technological options are being considered to remove CBZ and other PPCPs from wastewaters, including (photo)oxidation processes, membrane separations, and adsorption-based separations. Hydrophobic high-silica and all-silica zeolites have been identified as promising adsorbents for the removal of organic contaminants. In this contribution, the adsorption of CBZ in 11 all-silica zeolites having different pore sizes and connectivities was investigated using dispersion-corrected density functional theory (DFT) calculations (CP2K code, rev-vdW-DF2 functional). On the basis of calculations considering a single CBZ molecule per simulation cell, IFR- and AFI-type all-silica zeolites were identified as systems with the highest affinity towards CBZ. Both of these frameworks contain one-dimensional channels outlined by 12-membered rings of SiO4 tetrahedra. An analysis of the lowest-energy configurations showed that a “good fit” of CBZ into the pores, which maximises van der Waals interactions, is critical to achieve a high affinity, whereas hydrogen bonds are only of minor importance. Further calculations investigating the adsorption of two CBZ molecules per simulation cell indicated that attractive guest-guest interactions are more significant in zeolites with larger pores.

Funding by the German Research Foundation (project 455871835) is gratefully acknowledged.



MON: 2
Topics: 1.3 Bridging length and time scales in the modelling of geomaterials

A normal to incommensurate phase transition in malayaite, CaSnOSiO4

Thomas Malcherek1, Michael Fischer2, Boriana Mihailova1, Carsten Paulmann1

1Universität Hamburg, Germany; 2Universität Bremen, Germany

Malayaite, the tin analogue of titanite, has been shown to develop an incommensurately modulated phase with a modulation vector of q=0.26b* at a temperature of 20K [1]. The occurence of the modulated phase confirms density functional perturbation calculations of the phonon dispersion, indicating phonon softening in this particular range of k-space. Single crystal X-ray diffraction experiments at beamline P24 of PETRAIII/Desy at variable temperatures between 20 and 100K indicate a transition temperature of 48±3K for the corresponding normal to incommensurate phase transition. On approaching the phase transition temperature from below, the modulation vector remains almost constant, while the intensity of the satellite diffration maxima decreases. The crystal structure transforms from the C2/c(0b0)s0 superspace group to C2/c. The phase transition is discussed in relation to further anomalies observed between 90K and 400K by single crystal X-ray diffraction and Raman spectroscopy and in particular in relation to mode softening of a low frequency Bg-mode involving Ca-motion parallel to [001]. This mode softening is observable over the entire temperature range between 400K and 90K and culminates in the modulated low temperature structure of malayaite, as evidenced by the corresponding instability observed in the calculated phonon dispersion.

[1] Malcherek T., Paulenz B., Fischer M., Paulmann C. (2020) Acta Cryst. B76, 316-321



MON: 3
Topics: 1.3 Bridging length and time scales in the modelling of geomaterials

Speciation of Rare Earth Elements (REEs) in hydrothermal systems

Rajorshi Chattopadhyay, Sandro Jahn

Institute for Geology and Mineralogy, University of Cologne, Germany

The Rare Earth Elements (REEs) are an important group of elements both geologically as well as economically. REEs find important applications in the fields of green energy, electric vehicles and electronics. They are also important tracers for geological processes under hydrothermal /high grade metamorphic conditions. The ability of fluids to mobilise the REEs depend on the chemical composition and the presence of suitable ligands like chloride, fluoride. Ab initio molecular dynamics simulations (AIMD) have been used to predict stability constants of various REE complexes and REE speciation under hydrothermal conditions (Stefanski and Jahn, 2020; Guan et al, 2020). However, AIMD simulations often suffer from significant finite time and size effects. Classical potentials on the other hand solve the problems of AIMD to some extent but they often oversimplify the description of atomic interactions. Several interesting phenomena like formation and breaking of bonds are not captured by classical potentials. Hence a good compromise would be to use ReaxFF (Duin et al. 2001). Another potential drawback of simple pairwise additive classical potentials is their implicit description of multipolar effects which play a significant role in solvation of ions in aqueous solvents. These multi-body effects become essential when dealing with multivalent ions, in concentrated solutions and in inter-facial environments (Tazi et al, 2012). Here, we discuss results from preliminary simulations with classical potentials (Migliorati et al. 2017). We demonstrate the finite size and finite time effects associated with AIMD and how classical potentials can be potentially used to overcome them.



MON: 4
Topics: 2.1 Changes of solid Earth´s processes through deep time

The Malolotsha Klippe: Large-scale subhorizontal tectonics along the southern margin of the Archean Barberton Greenstone Belt, Eswatini

Christoph Heubeck1, Benjamin Heredia2, Tonny Thomsen2, Armin Zeh3, Philipp Balling1

1Friedrich-Schiller-University Jena, Germany; 2Geological Survey of Denmark and Greenland (GEUS); 3Karlsruhe Institute of Technology

Whether Archean tectonics were horizontally or vertically dominated is debated because arguments bear on the kinematics and thermal state of the Archean mantle and constrain the formation of the earliest continental crust. Deformed strata of greenstone belts figure prominently in this debate because they record long periods and multiple deformation phases. Among the best-preserved belts counts the Barberton Greenstone Belt (BGB) of southern Africa. Geological mapping of its southern part in Eswatini (Swaziland), combined with U-Pb zircon dating, show that the region preserves a tightly re-folded imbricate thrust stack in which metavolcanic and -volcaniclastic strata of the Onverwacht Group, deposited at 3.34-3.29 Ga, have been thrust on top of ca. 3.22 Ga siliciclastic strata of the Moodies Group. The structurally highest element, the Malolotsha Syncline, forms a tectonic klippe of substantial size and is >1450 m thick. Forward modelling of a balanced cross section indicates that this thrust stack was part of a northwestward-verging orogen along the southern margin of the BGB and records a minimum horizontal displacement of 33 km perpendicular to its present-day faulted, ductily strained and multiply metamorphosed margin. Because conglomerate clasts indicate a significantly higher degree of prolate strain which extends further into the BGB than at its northern margin, the late-stage tectonic architecture of the BGB may be highly asymmetrical. Our study documents that the BGB, and perhaps other Archean greenstone belts, preserves a complex array of both vertically- and horizontally-dominated deformation styles that interfered with each other at small regional and short temporal scales.



MON: 5
Topics: 2.2 From dust to planets

Stable iron isotope fractionation in metal sulfidation at 600–1200 °C

Christian J. Renggli1, Ingo Horn2, Stephan Klemme1, Stamatis Flemetakis1, Stefan Weyer2

1Institute for Mineralogy, University of Münster, Germany; 2Institute for Mineralogy, University of Hannover, Germany

Iron metal and troilite co-exist in ordinary chondrites and iron meteorites [1,2]. Here, we present results from Fe metal equilibrium sulfidation experiments in evacuated silica glass tubes at 600-1200 °C. The two distinct phases, Fe and FeS, were analyzed for their δ56Fe and δ57Fe compositions with MC-ICP-MS (Thermo Scientific Neptune Plus). The materials were ablated using a Spectra-Physics Solstice femtosecond laser ablation system at the Institute of Mineralogy, University Hannover, see [3] for analytical details.

At 600–1000 °C the sulfidation reaction occurred in the solid state and Fe metal is coated by FeS, whereas above 1000 °C we observe Fe and FeS melts. We insured isotopic equilibration by running experiments with different durations. At 600 °C and 71h we observed kinetic fractionation effects, whereas after 260h the sulfide coating was isotopically homogeneous. Overall, FeS is systematically heavier compared to the Fe metal, and the isotopic fractionation decreases with increasing temperature from 600-1200 °C. However, a comparison of the experimental results with δ56Fe data from ordinary [1] and iron [2] meteorites shows the opposite fractionation trend. In the meteorites the FeS is always isotopically lighter compared to the Fe metal. We suggest that this is due to kinetic fractionation effects that occur during cooling of Fe-FeS melts in the meteorites, whereas our quenched experiments retained the equilibrium δ56Fe fractionation.

[1] Needham A. W. et al. (2009) GCA 73:7399–7413. [2] Williams H. M. et al. (2006) EPSL 250:486–500. [3] Horn I. (2007) Spectrochim. Acta B 62:410–422.



MON: 6
Topics: 2.2 From dust to planets

Experimental quantification of the degassing of chalcophile and siderophile elements from metal and sulfide melts

Edgar S. Steenstra, Christian Renggli, Jasper Berndt, Stephan Klemme

WWU Münster, Germany

The chemical composition of magmatic iron meteorites provides fundamental insights into planetary accretion processes. They are distinguished based on their trace element compositions and could represent the cores of more than 50 parent bodies1. The primary difference between the different groups is the degree of volatile element depletions, which increases from class I to IV iron meteorites2. The volatile element loss could have occurred prior to (i.e. nebular) or during parent body accretion/differentiation, for example during exposure of a liquid core following a catastrophic impact3. Investigating the mechanisms of volatile loss from requires experimental constraints on their volatility, for example during evaporation. We therefore experimentally quantified the evaporation of the nominally volatile, transitional and refractory chalcophile and siderophile from Fe-C and Fe-S melts, respectively. Their evaporation was studied as a function of pressure (high vacuum to 1 bar), temperature (1573-1823 K), composition (Fe, FeS) and time (min´s to hours). The results show that the volatilities are significantly different than previously assumed, and that their volatility may be strongly and distinctly affected by the composition of the melt from which they evaporate. The new data is discussed in light of current models that describe volatile element depletions in magmatic iron meteorite parent bodies.

(1) Goldstein et al. (2009) Chemie Der Erde - Geochemistry (2) Scott & Wasson (1975) Rev Geophys (3) Kleine et al. (2018) LPSC 2083.



MON: 7
Topics: 2.2 From dust to planets

Chemical composition and petrography of recent type 1 and 2 carbonaceous chondrite falls

Frank Wombacher1, Imene Kerraouch2, Addi Bischoff3

1Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany; 2ARES, NASA Johnson Space Center, Houston TX, 77058, USA; 3Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany

We analysed the recent (2019 - 2021) brecciated carbonaceous chondrite falls Flensburg (C1), Tarda (C2,) Kolang (CM1/2), Aguas Zarcas (CM2), and Winchcombe (CM2) together with Murchison and Paris for their chemical composition using ICP-MS and for Hg abundances using a direct mercury analyser. Chemical variations were evaluated considering new and published petrological and mineralogical data.

Aguas Zarcas #1 is enriched in Hg relative to a CI reference value of 258 ng/g, while Flensburg, Kolang, Winchcombe and the fusion crust-rich samples Aguas Zarcas #3a and 3b are depleted. The Hg contents in Aguas Zarcas #2 and 4 and both Tarda specimens are roughly similar to those extrapolated from plateau volatile element abundances, with a best fit if a CI Hg content of about 210 ng/g is assumed.

For Flensburg, Kolang, Aguas Zarcas #1 and 2, Murchison and Paris, elements analysed by ICP-MS display a typical CM composition, but Tarda shows less depletion of moderately volatile elements. Deviations for Ca, Sr, Ba, Na, Rb, and Cs in the pre-rain samples Aguas Zarcas #3a and 3b suggest that these elements were mobile within the parent body. The metal-rich lithology of Aguas Zarcas #4 displays no systematic enrichment in siderophile elements, but peculiar enrichments of refractory elements, most significantly for Zr, Hf, W, Ir, and some heavy REE. The enrichment of Ca, Sr, Mn, and Mg esp. in Tarda #1 reflects the high abundance of carbonates. Unlike for Tarda and some Aguas Zarcas samples, the Flensburg CM-related composition was not affected by intense aqueous alteration.



MON: 8
Topics: 3.1 Novel isotopic insights into high-temperature geochemical processes

Potassium isotope systematics in ocean island basalts from Madeira (East Atlantic) imply recycling of distinct portions of subducted oceanic crust

Haiyang Liu2,3, Ying-Yu Xue2,3, Jörg Geldmacher1, Uwe Wiechert4, Tinggen Yang2,3,5, Fanfan Tian2,3,5, Hai-Ou Gu6, He Sun6, Kun Wang7, Wei-Dong Sun2,3,5

1GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany; 2Center of Deep Sea Research, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, P. R. China; 3Deep-Sea Multidisciplinary Research Center, Qingdao Pilot National Laboratory of Marine Science and Technology, Qingdao, P. R. China; 4Institute of Geological Sciences, Freie Universität Berlin, Berlin, Germany; 5University of Chinese Academy of Sciences, Beijing, P.R. China; 6Ore Deposit and Exploration Center, Hefei University of Technology, Hefei, P. R. China; 7Department of Earth and Planetary Sciences, Washington University in St. Louis, St Louis, USA

Subduction of oceanic lithosphere is widely considered as the primary cause of mantle heterogeneity as reflected by the chemical variation of ocean island basalts. However, the fate of deeply subducted oceanic lithosphere (i.e., remaining intact, getting segmented or completely destroyed and intermixed with ambient mantle) is still largely unknown. Based on trace element and radiogenic isotope systematics, it has been suggested that the geochemical difference of shield and post-erosional stage lavas of the volcanic Madeira archipelago reflects recycling of different portions of subducted lithosphere (e.g., Geldmacher and Hoernle, 2000, EPSL 183; Gurenko et al. 2013, Lithos 170-171). Accordingly, the geochemical composition of the shield stage magmas reflects altered upper oceanic crust, while the isotopically less enriched post-erosional magmas preferentially stem from less-modified, lower crustal/lithospheric mantle portions of the recycled slab. New, high precision potassium (δ41K of -0.75‰ to -0.50‰) and oxygen (δ18O of 4.90‰ to 5.21‰ in olivine phenocrysts) isotope data from Madeira lavas support this model. Subduction dehydration can cause large K isotope fractionation in the upper, seawater-altered parts of oceanic crust resulting in lighter K isotopes (lower δ41K) in ocean island basalts containing such material. The measured δ41K represents the lowest range among oceanic basalts published so far and overlaps with obducted eclogite, indicating the involvement of dehydrated oceanic crust. The correlation of light K with light O and enriched radiogenic isotope ratios supports the model that Madeira’s magma source contains different portions of subducted oceanic crust, which were preserved over millions of years without significant intermixing.



MON: 9
Topics: 3.1 Novel isotopic insights into high-temperature geochemical processes

Kinetic zinc isotope fractionation in olivine phenocrysts records magma evolution history of intra-plate basalts

Chun Yang1,2, Sheng-Ao Liu2

1Institut für planetologie, WWU Münster, Germany; 2State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, China

Zinc isotope systematics of basaltic magmas have been widely used as novel proxies for terrestrial mantle heterogeneity induced by recycled crustal materials [1-2]. The influence of mineral-melt isotope disequilibrium during magma differentiation on Zn isotopic composition of basaltic melts, nonetheless, has received limited attention. No quantitative constraint has yet been given for the diffusion-driven Zn isotope fractionation between olivine crystals and melts. Here we present high-precision zinc isotope data (δ66ZnJMC-Lyon) for a series of olivine phenocrysts separated from intra-plate basalts from the Jiaodong Peninsula in Eastern China, together with in-situ trace element analysis. Olivine phenocrysts have Zn isotopic compositions which are too light in comparison with the host basaltic melts to be explained by equilibrium isotope fractionation at magmatic temperatures. Instead, the decrease of δ66Zn values with decreasing Mg# and increasing Zn contents in olivine phenocrysts suggests diffusion-driven kinetic fractionation during olivine crystallization. The data is well-fitted with a diffusion model in which Zn diffuses from surrounding melt into olivine crystals due to the large chemical gradient with a kinetic Zn isotope fractionation factor βZn of 0.07. It is suggested that diffusion-induced isotope disequilibrium during olivine crystallization may drive Zn isotopic composition of the residual melt toward heavier values by utilizing the fractional crystallization model. Thus, kinetic effects between phenocryst and melt must be considered when applying zinc isotope systematics of any basaltic magma to probe the source heterogeneity.

[1] Liu et al., 2016, EPSL 444, 169–178. [2] Beunon et al., 2020 Earth-Sci. Rev., 103174



MON: 10
Topics: 3.2 Composition and evolution of deep planetary interiors

Complex electronic, magnetic, and structural transformations in FeO

Xiang Li1, Elena Bykova2,4, Georgios Aprilis2,3, Denis Vasiukov2,3, Stella Chariton2, Valerio Cerantola5, Maxim Bykov2, Anna Pakhomova5, Fariya Akbar2, Elena Mukhina6, Davide Comboni5, Catherine Mccammon2, Aleksandr Chumakov5, Carmen Sanchez-Valle1, Leonid Dubrovinsky2, Ilya Kupenko1

1University of Muenster, Germany; 2Bayerisches Geoinstitut (BGI)–Germany; 3Laboratory of Crystallography, Material Physics and Technology at Extreme Conditions, Universität Bayreuth–Germany; 4Deutsches Elektronen-Synchrotron (DESY)–Notkestraße85 D-22607 Hamburg, Germany; 5ESRF-The European Synchrotron (ESRF) France; 6KTH Royal Institute of Technology – Sweden

Iron oxides are important materials for Geoscience but also for basic science and applied technologies (Kupenko et al., 2019). Iron monoxide is likely to be the final constituent of the evolution of subducted banded iron formations and might be a source of the low-velocity zones at the Earth’s core-mantle boundary (Dobson and Brodholt, 2005). The stability and high-pressure properties of FexO could, thus, determine the fate of banded iron formations and their potential role in processes in Earth and planetary interiors, including controls on redox cycles.

FexO has the NaCl (B1) structure at ambient pressure and temperature and transforms into rhombohedral distorted-B1 phase (rB1) at about 16 GPa. A further transition from a rhombohedral rB1 phase to a hexagonal B8 phase has been proposed at 74 GPa and 900 K (Fei and Mao, 1994). Although numerous studies were focused on the investigation of the electronic and magnetic properties and phase diagram of FexO, information on the Fe2+/Fe3+ interplay, magnetic and structural coupling of FexO at high pressures and high temperature are very limited.

We will present our investigation on the pressure dependence of the electronic, magnetic and structural properties of FexO by means of Synchrotron Mössbauer Source spectroscopy and Single-Crystal X-ray diffraction with diamond anvil cells up to 94 GPa and 1200 K. We will discuss the interplay between Fe2+ and Fe3+ and its effects on the electronic and magnetic properties of FexO and their potential role in the mineralogy, chemistry, and physics of the Earth’s deep interior.



MON: 11
Topics: 4.1 Magmas and Fluids in the Crust

Basalts from the intratransform domain at the Doldrums Megatransform (7-8° N MAR) reveal mantle re-melting

Camilla Sani1,2, Alessio Sanfilippo1,3, Felix Genske2, Sergey Skolotnev4, Marco Ligi5, Andreas Stracke2

1Department of Earth and Environmental Science, University of Pavia, Pavia, Italy; 2Institut für Mineralogie, Westfälische Wilhelms-Universität, Münster, Germany; 3Istituto di Geoscienze e Georisorse, Consiglio Nazionale delle Ricerche, Pavia, Italy; 4Geological Institute, Russian Academy of Sciences, Moscow, Russia; 5Consiglio Nazionale delle Ricerche, ISMAR, Bologna, Italy.

In the Equatorial Mid Atlantic Ridge at 7-8°N the Doldrums Fracture Zone (FZ) is located: a complex transform system characterized by four ‘intratransform’ ridge segments (ITRs) bounded by five active transforms (Skolotnev at el., 2020). We determined major element, trace element and Sr, Nd, Hf and Pb isotope compositions for on-axis lavas erupted along the entire fracture domain. Basalts from the central ITRs are selectively enriched in alkalis (Na2O+K2O= 4.3 wt%; Na8 up to 3.7) and LREE (La/SmN=0.86 -0.97), in agreement with low melting degrees in a cold intra-transform regime. Despite this, they have the most depleted Sr and Pb isotope compositions in the entire Equatorial MAR (i.e. 87Sr/86Sr = 0.70237 and 206Pb/204Pb = 18), coupled with comparatively less depleted Nd and Hf isotope compositions, which instead plot in the field of regional MORB (143Nd/144Nd = 0.5131-0.5232; 177Hf/176Hf = 0.2831-0.2832). Hence, the magmatism at the ITRs was predominately sourced by a depleted mantle source, melted at very low melting degrees. On this basis we suggest that the upper mantle currently melting beneath the central portion of the Doldrums FZ has previously undergone partial melting at the MAR axis, consuming the most fertile, isotopically enriched heterogeneities.

Skolotnev, S.G., Sanfilippo, A., Peyve, A., Muccini F., Sokolov, S. Y., Sani, C., Dobroliubova, K.O., Ferrando, C…& Ligi, M., 2020. Large-scale structure of the Doldrums multi-fault transform system (7-8ºN Equatorial Atlantic): preliminary results from the 45th expedition of the R/V AN Strakhov. Ofioliti, 45(1), 25-41.



MON: 12
Topics: 4.1 Magmas and Fluids in the Crust

In-situ fractionation at the decameter scale in lower oceanic crust

Dominik Mock1,2, David Axford Neave3, Samuel Müller4, Dieter Garbe-Schönberg4, Benoît Ildefonse2, Jürgen Koepke1, Oman Drilling Project Science Team5

1Institut für Mineralogie, Leibniz Universität Hannover, Germany; 2Géosciences Montpellier, CNRS, Univ. Montpellier, Montpellier, France; 3Department of Earth and Environmental Sciences, University of Manchester, United Kingdom; 4Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Germany; 5Geoscience Institutions, Worldwide

As the best-preserved fragment of paleo oceanic crust on land, the Samail ophiolite (Sultanate of Oman) allows extensive field studies on fast-spread lower oceanic crust. Drill core GT1 of the Oman Drilling Project in the frame of ICDP (International Continental Scientific Drilling Program) spans about 400 m from the layered gabbros between ~1200 and 800 m above the crust-mantle boundary (maM). The drilled samples are mostly gabbros or olivine gabbros and we applied petrological, geochemical, and microstructural methods to identify those magmatic processes relevant for the lower crust accretion. Mg# (Mg/Mg+Fe x 100; molar basis) in olivine and clinopyroxene and the Ca# (Ca/Ca+Na x 100; molar basis) in plagioclase show parallel fractionation trends from 800 to 1070 maM which can be subdivided into four 25 to 80 m-thick smaller trends. Above 1070 maM, phase compositions change towards more primitive compositions over a 15 m-thin horizon, revealing decameter-scale fractionation over the uppermost 80 m of the core. These trends are confirmed by bulk rock Mg# and Cr/Zr ratios and thermodynamic modeling suggests that they can result from in-situ fractionation by a crystallization degree of less than 30 mol% followed by primitive melt replenishment. Thus, the necessity of removing latent heat which is regarded as critical in terms of in-situ crystallization is only limited, because most melt migrates upwards, without crystallizing. Our results suggest that magma replenishment and fractional crystallization are the key processes responsible for the accretion of the layered gabbro section of the Oman paleocrust.



MON: 13
Topics: 4.1 Magmas and Fluids in the Crust

Age differences between separate magma pulses in two laccoliths (Halle Volcanic Complex): insight into processes of silicic magma formation

Arkadiusz Przybyło1, Anna Pietranik1, Christoph Breitkreuz2

1University of Wrocław, Poland; 2TU Bergakademie Freiberg, Germany

The Halle Volcanic Complex includes several laccoliths emplaced during Carboniferous-Permian flare-up (Breitkreuz & Kennedy, 1999). Previous dating of the laccoliths yielded a range of ages from 301±3 Ma (Landsberg) to 292±3 Ma (Petersberg). Textural and whole rock chemical composition of samples from several depths from both laccoliths suggest formation of the laccoliths in several pulses and in this study we have checked if a complementary record is preserved in chemical composition of accessory phases. Altogether seven depths have been analyzed from two laccoliths including electron microprobe analyses of zircon and apatite and U-Pb SHRIMP dating. Additionally four depths were analysed for U-Pb zircon age by CA-ID-TIMS. Zircon is chemically homogenous within and between laccoliths and has similar sets of inclusions. On the other hand, apatite shows variable Nd contents decreasing with depth for both laccoliths and apatite from Petersberg has more Cl, when apatite from Landsberg has more Na. The implication is that apatite chemistry is better at recording magma evolution than zircon. SHRIMP ages are scattered over 30 Ma for a single sample, which suggests the presence of antecrysts and lead-loss, or alternatively indicates formation of the laccoliths over a prolonged period of time.

Acknowledgements: The research was funded by the National Science Centre (Poland) the OPUS project UMO-2017/25/B/ST10/00180 to APietranik.

Breitkreuz, C., Kennedy, A. (1999) Magmatic flare-up at the Carboniferous/Permian boundary in the NE German Basin revealed by SHRIMP zircon ages. Tectonophysics. 302, 307-326.



MON: 14
Topics: 4.2 Advances in Geochronology: From present techniques to future applications

Mantle metasomatism constraint: LA-ICPMS U-Pb dating of single garnet xenocrysts from the V. Grib kimberlite, Russia

Leo J. Millonig1, Elena V. Agasheva2, Alexey M. Agashev2, Richard Albert1, Aratz Beranoaguirre1,3, Axel Gerdes1

1FIERCE, Goethe University Frankfurt am Main; 2Sobolev Institute of Geology and Mineralogy, Novosibirsk; 3Karlsruher Institut für Technologie, Karlsruhe

Mantle metasomatism largely controls the physical and chemical properties of the lithospheric mantle and exerts control over the genesis of kimberlitic magmas and diamond formation. In this context, garnet xenocrysts from kimberlites are fundamental for decoding metasomatic events in the lithospheric mantle and to decipher the variation in rock types with depth. However, dating mantle lithologies and processes is complicated by high ambient temperatures that allow the equilibration of most isotopic systems up to the time of kimberlite eruption.

In this study we investigate garnet xenocrysts from the ~376 Ma V. Grib kimberlite, Russia to evaluate the potential of garnet for dating metasomatic events in the subcontinental lithospheric mantle. Based on major and trace element compositions and REE patterns, harzburgitic, wehrlitic, lherzolitic (4x) and megacrystic garnet xenocrysts are distinguished.

Our preliminary data indicates that garnet can record the ages of different metasomatic events. Garnet from harzburgitic and lherzolithic lithotypes indicate at least 30 myr of mantle metasomatism prior to kimberlite eruption. This age spread reflects distinct metasomatic events, but partial resetting of the U-Pb isotope system also has to be considered.



MON: 15
Topics: 4.2 Advances in Geochronology: From present techniques to future applications

Formation and deformation of Triassic skarn (Uppermost Unit, Crete/Greece)

Gernold Zulauf1, Axel Gerdes2, Jochen Günther Krahl3, Jolien Linckens1, Horst Marschall2, Leo Millonig2, Nicolas Neuwirth1, Rainer Petschick1, Jörg Pfänder4, Paris Xypolias5

1Universität Frankfurt a.M., Germany; 2FIERCE, Universität Frankfurt a.M. Germany; 3Agnesstraße 45, 80798 München, Germany; 4TU Bergakademie Freiberg, Germany; 5University of Patras, Greece

The nappes of the Uppermost Unit of Crete are counted among the most enigmatic constituents of the Eastern Mediterranean. U-Pb dating of zircons separated from felsic metavolcanics of the deepest Preveli nappe yielded Triassic emplacement ages at 237.3 ±1.8, 241.5 ±1.2 and 242.1 ±1.2 Ma. U-Pb dating of andradite-grossular of subvolcanic skarn yielded the same age at 239.3 ±2.3 Ma. The skarn is dominated by hydrous phases (ferri-actinolite, hydro-grandite, epidote), which developed at T = 400 – 450 °C in a rift-related setting due to fluid-assisted metasomatic reactions between limestone and mafic veins. Thus, U-Pb dating of skarn grandite allows dating the complementary record of hydrothermal activity related to the cooling of the causative melt. Early Cretaceous subduction caused deformation under epidote-blueschist facies conditions at T = 360 ±40 °C and P >1.0 GPa. An 39Ar-40Ar age of 125 ±10 Ma obtained from synkinematic ferri-winchite is interpreted to reflect the time of Eohellenic HP-LT metamorphism. During subduction, the differential stress was >300 MPa. Under these conditions, the garnet strain was accommodated not only by fracturing, but also by strain-induced grain boundary migration and subgrain formation. Thus, crystal plastic deformation of garnet is possible at temperatures far below the threshold temperature (ca. 500 °C) commonly reported for dislocation creep.

The new ages obtained from the Preveli nappe suggest the Uppermost Unit of Crete to be derived either from the peri-Rhodope domain of the Internal Hellenides or from the Pontides of northern Turkey.

Funding by DFG (Zu 73-34) is acknowledged.



MON: 16
Topics: 4.3 The role of fluids in metamorphic and metasomatic reactions

C-O-H-S fluids released by subducted serpentinite and the implications for arc-magma oxidation

Wenyong Duan, Hans-Peter Schertl, Arne P Willner

Ruhr-Universität Bochum, Germany

Serpentinites are able to carry H2O, ferric iron, carbon and sulfur into subduction zones, where they stepwise released fluid during dehydration. These C-O-H-S fluids are intimately linked to magma oxidation and ore formation within magmatic arcs. However, the mechanism of the transfers of carbon, sulfur and ferric iron into fluids is poorly known. It is also controversially discussed if C-O-H-S fluids can oxidize arc magmas. Our new thermodynamic models focus on the species produced by C-O-H-S fluids during subduction. Closed system modeling provides molar concentrations of such species under different P-T conditions, showing that reducing species generally have high solubilities at low P-T conditions. Oxidizing species mainly remain in the fluid after increasing P-T conditions. Open system fluid fractionation shows that only 5-14% of carbon is transported to the mantle wedge, while the amount of sulfur loss is as high as 55-100% at sub-arc depths. Almost all lost carbon and sulfur are released as oxidizing species. The redox properties of the fluids are controlled by sulfur, resulting in an oxygen fugacity of the fluids being 0.6-0.95 log units higher than that of the HM buffer. Sulfur loss is a function of the whole-rock compositions and the subduction geothermal gradient, demonstrating elevated sulfur fluxes to be released from serpentinite in cold subduction zones compared to warm ones. Our modeling results are consistent with petrological observations and global-arc-basalt oxygen fugacity calculations and highlight that the C-O-H-S fluids released from the subducted slab can considerably contribute to the composition of arc magmas.



MON: 17
Topics: 4.4 Deciphering orogenic processes: Combining metamorphism, anatexis, metasomatism and geochronology

Low-grade Blueschist-facies Metamorphism in the Central Yarlung Suture Zone, Southern Tibet

Guangming Sun

Ruhr-University Bochum, Germany

Blueschists are mostly metamorphosed basaltic rocks that form at high-pressure and low-temperature conditions and characterize sodic amphibole as the major constituent mineral. Blueschists in southern Tibet are distributed as discontinuous blocks in sedimentary-matrix mélange within the Yarlung Suture Zone (YSZ). In this paper, petrographic and mineral chemical studies and pseudosection modelling were carried out to constrain the metamorphic conditions and evolution of blueschists in the central YSZ. Blueschists from Sangsang area are characterized by presence of sodic amphibole, epidote, chlorite, muscovite, omphacite and sphene in the peak metamorphic assemblage. Sodic amphiboles in Sangsang blueschist are identified as magnesioriebeckite in chemical compositions. Pseudosection calculations and intersection of isopleths indicate peak metamorphic conditions of 7.8kbar at 355°C. Blueschists from Kadui area contain metamorphic assemblages of sodic amphibole, epidote, chlorite, omphacite with accessory sphene. The amphibole in Kadui blueschist shows zoned from actinolite core to ferrowinchite/riebeckite rim and actinolite outmost rim. The metamorphic conditions of Kadui blueschists are estimated to be 360°C and 7.5kbar based on available phase equilibria and sodic amphibole compositions. These P–T conditions are consistent with metamorphism in the low-grade blueschist facies, burial depths of 25–27 km and a thermal gradient of 13–14°C/km. Our new findings indicate that the blueschist in the central part of YSZ experienced low-grade blueschist-facies metamorphism at shallow depths in subduction channel as a response to a northward subduction of the Neo-Tethyan oceanic lithosphere during the initial India–Asia collision stage.



MON: 18
Topics: 4.4 Deciphering orogenic processes: Combining metamorphism, anatexis, metasomatism and geochronology

First Lu-Hf ages of garnet-bearing lithologies from the Saxonian Granulite Massif

Madeline Richter1, Sebastian Weber2, Niko Froitzheim3, Kathrin Fassmer4, Carsten Münker5, Kamil Ustaszewski1

1Friedrich-Schiller Universität Jena, Germany; 2Landesamt für Umwelt, Landwirtschaft und Geologie Sachsen; 3Universität Bonn; 4Universität Innsbruck; 5Universität zu Köln

The Saxonian Granulite Massif is an antiformal gneiss dome with granulite facies rocks in the core, enwrapped by uppermost amphibolite to lower greenschist facies metasediments. Their subduction and exhumation histories during the Variscan orogeny are still poorly understood. Samples of two garnet-bearing serpentinites and one eclogite from the dome-core, as well as one garnet-cordierite gneiss from the lowermost schist-cover were dated using Lu-Hf chronometry.

The granulitic core mostly consists of leucocratic granulites with scarce and laterally discontinuous slivers of mafic and ultramafic rocks. All samples were taken at the largest occurrence of ultramafics at the Rubinberg, where granofelsic eclogites (CPx, Grt, Pl, Rt) are found as two 1 m-thick, foliation parallel layers within foliated garnet-bearing serpentinites (Grt, relics of CPx, Amp, Ol, Spl). Garnet is better preserved within eclogites than in serpentinites. Within eclogites, EPMA major element zoning profiles of garnet blasts show a prograde metamorphic path, partially modified by diffusional relaxation leading to flattening of chemical zoning profiles. Complete homogenization of major elements is characteristic for all pyrope-rich, strongly kelyphitic garnets in the serpentinites. Garnet blasts within the garnet-cordierite gneiss (Pl, Grt, Sil, Bt, Crd, Qtz, Ilm, Spl) reveal complex compositional zoning profiles with a prograde metamorphic zonation pattern in the core and a secondary increase of Ca and Mn in the rims.

The eclogite yielded a Lu-Hf age of 347.5±6.7 Ma, which is interpreted to indicate the timing of peak metamorphism within the granulitic core, predating the retrograde exhumation-related fabrics. Ages of serpentinites and gneisses are still pending.



MON: 19
Topics: 4.4 Deciphering orogenic processes: Combining metamorphism, anatexis, metasomatism and geochronology

Timing and metamorphism of the root of a magmatic arc on the West Gondwana margin: a case study of the Socorro Nappe and São Roque Domain in south-eastern Brazil

Mikaella Balis1, Bernhard Schulz1, Mario da Costa Campos Neto2

1TU Bergakademie Freiberg, Germany; 2University of São Paulo, Brazil

The assembly of West Gondwana resulted in a high-grade nappe system of south-eastern Brazil that comprises a magmatic arc remnant (Socorro-Guaxupé Nappe). The UHT metamorphism is product of the collision between the Paranapanema block (active margin) and the São Francisco craton (passive margin) and decompression, but also related to a pre-collisional stage (Rocha et al., 2017; Tedeschi et al., 2018). The U-Pb ID-TIMS and U-Th-PbT EPMA monazite peak metamorphic ages systematically decrease towards the lower nappes describing an orogenic front migration from ca. 630-570 Ma (Campos Neto et al., 2011; Westin et al., 2021). The southernmost segment (Socorro Nappe) comprises gneisses with varied degrees of migmatization that unveil UHT-HT conditions, e.g., spinel + quartz and melt (quartz + K-feldspar) inclusions in garnet, neosomes with garnet + orthopyroxene and garnet + cordierite that are associated with amphibole ± pyroxene-bearing mesocratic gneisses. The paragneisses host a peak assemblage of garnet + sillimanite (needle trail inclusions) whereas biotite + sillimanite in the foliation are potentially retrograde. SEM-MLA and BSE imaging of monazite reveal complex microstructures. Monazite from the paragneisses displays homogeneous, moderate zonation and/or cloudy internal structures. A spinel-cordierite-garnet leucosome hosts peritectic garnet in which monazite inclusions are cloudy and weakly zoned. EPMA core-to-rim profiles of garnet show Fe-Mg zonation in a paragneiss whereas none in the neosomes. The overall composition is almandine and pyrope (XAlm 55-70%; XPrp 25-37%) and low Ca. We combine geothermobarometry and petrochronology of monazite to understand the metamorphic transition from lower to upper crustal rocks in the Neoproterozoic orogen.



MON: 20
Topics: 4.4 Deciphering orogenic processes: Combining metamorphism, anatexis, metasomatism and geochronology

No unique temperature of equilibration for mantle peridotites - Thermal histories told by differently diffusing cations based on novel calibrations

Vasileios Giatros1, Dimitrios Kostopoulos1, Panagiotis Pomonis1, Evangelos Moulas2

1National and Kapodistrian University of Athens, Greece; 2Johannes Gutenberg-Universität Mainz, Institut für Geowissenschaften, D-55128 Mainz, Germany

We generated novel thermometric formulae for cation exchange reactions between mantle minerals involving species of different diffusivities (FeMg orthopyroxene-spinel; CrAl & CaMg clinopyroxene-orthopyroxene) and used them in conjunction with published expressions (FeMg olivine-spinel; CaMgFe clinopyroxene-orthopyroxene) to decipher the thermal history of peridotites from diverse tectonic settings. When tested on abyssal peridotites, TCrAlopx-cpx vs. TCaMgcpx-opx form tight trends with TCrAlopx-cpx ≥ TCaMgcpx-opx at T<1060oC and TCrAl opx-cpx ≤ TCaMgcpx-opx at T>1060oC in accordance with crossing diffusivities of Cropx and CaMgcpx at about that temperature, with the latter becoming smaller at higher temperatures and blocking higher as the peridotites are quickly emplaced and cooling at the ridge. Both TCrAlopx-cpx and TCaMgcpx-opx are higher than the widely used TCaFeMgcpx-opx in abyssal peridotites by ~100°C on average. On a TCrAlopx-cpx vs. TFeMgopx-sp plot there is clear-cut distinction between peridotite massifs (major ocean basins, oceanic forearcs, oceanic backarcs, ophiolites, ocean-continent transitions, Alpine-type) from peridotite xenoliths (cratons, intracontinental rifts, continental backarcs, active continental margins, oceanic within-plate) with TCrAlopx-cpx being invariably larger than TFeMgopx-sp for the peridotite massifs reflecting the blocking of the slower-diffusing cations at higher temperatures upon cooling. The higher TFeMgopx-sp exhibited by the xenoliths are ascribed to some, probably magmatic, heating event at a time prior to their transport to the surface. The Alpine-type peridotites of Beni Bousera, Morocco, that were exhumed in the footwall of a lithosphere-scale extensional shear zone display increasing TCrAlopx-cpx and TCaMgcpx-opx towards the shear zone but flat TCaFeMgcpx-opx, TFeMgopx-sp and TFeMgol-sp profiles demonstrating the memory of the slower-diffusing cations.



MON: 21
Topics: 4.5 Tectonic Systems (TSK Open Session)

Physics of microfabric generation: insights from a new deformation theory

Falk H Koenemann

n.a., Germany

The mechanics of solids theory from the 18th C is obsolete since energetic physical thinking, thermodynamics, and bonds in solids were discovered in 1840-1870. Elastic deformation is by nature a change of state in the sense of the First Law of thermodynamics; this cannot be concluded from the common theory. A proper approach to elastic deformation – stress – must begin with the equation of state, and be based on the First Law. – The thermodynamic theory (in scalars P, V, T) is isotropic by nature. It has been transformed into vector field form (f, r, T) to consider anisotropic boundary conditions. The displacement field has a contracting eigendirection [ED] at 111°, an extending ED at 11° to the foliation plane. EDs can neither rotate nor shear. The maximum shear directions, the bisectors between the EDs, are also the directions of maximum angular velocity. Therefore, the common idea of crystallographic glide planes aligning with the bulk shear direction, thereby permitting unlimited dislocation glide, is unrealistic. Not the glide planes control the fabric orientation, but the maximum material anisotropy aligns with the extending ED. The crystals populating a maximum are in a locked position, they cannot glide. It follows that extended plastic flow by dislocation glide alone is physically impossible. Secondary processes must be active simultaneously, such as grain boundary glide, recovery, heterogeneous shear zones. The new approach correctly predicts all observed features of plastic simple shear, such as S‑C, sigma-delta clast systematics, and microfabric obliquity.



MON: 22
Topics: 4.5 Tectonic Systems (TSK Open Session)

Interim report about geological survey in the Monticiano-Roccastrada metamorphic core complex (MRMCC, S-Tuscany, Italy) with considerations about its stratigraphic and tectonic development

Hubert Engelbrecht

Environmental Geology, Germany

The study area is part of the Mid Tuscan Ridge: a linear belt of metamorphic core complexes, exhumed during M-L-Tertiary times. They separate the N-Apenninic main belt from the Tuscan metamorphic zone, which originated during the opening of the N-Tyrrhenian back arc basin. This resulted from postcollisional rollback of the steeply W-dipping Adriatic subduction zone: effecting the migration of eastbound, paired compressional-extensional deformation fronts and of magmatism in the overlying crust (literature data).

The central part of the MRMCC (Farma Valley) was chosen for revision of geological field work. The already accomplished map part including resulting stratigraphic and tectonic facts are displayed:

Results: Above a fragmented and extended uniform base - Devonian pelagites - different Carboniferous, coeval, predominantly siliciclastic depositional areas developed as highstand systems tract above a downlap surface. Their recent proximality trend is westbound and their sedimentary environments, separated by normal faults, represent the shelf, lower slope, base of slope and basin margin. Sediment input was triggered by tropical storms and/or seaquakes. The deposits of these environments are covered by regressive, littoral-deltaic siliciclastics (Permian).

During E-M-Tertiary subduction related tectonic burial, the Carboniferous normal faults were reactivated, so that mentioned slope and basin deposits were thrusted onto inner shelf deposits. M-L-Tertiary unroofing caused exhumation from ca. 25 km depth. A megabreccia got exposed. It is arranged in subzones, characterised by distinctive metamorphism and deformation.

Farma Valley is probably geomorphological expression of an exhumed tear fault, part of the fracture system controlling the eastward migration of the Tuscan Magmatic Province.



MON: 24
Topics: 4.5 Tectonic Systems (TSK Open Session)

Rheological inversion and mullion formation of a composite sill under bulk constriction (Odenwald, Germany).

Janet Zulauf1, Jolien Linckens2, Axel Gerdes1, Horst Marschall1, Filip Loeckle3, Harro Schmeling1, Gernold Zulauf1

1Goethe Univerity / Institut for Geoscience / Germany; 2Tata Steel / R& D / CA Ijmuiden / Netherland; 3BGR Hannover / Germany

We present new data from a composite sill, which intruded at deep structural levels (ca. 18 km depth) into quartzmonzodiorite of the southern Odenwald. Zircons and titanites of the quartzmonzodiorite yielded similar U-Pb ages at 344.3 ±0.6 and 343.2 ±2.1 Ma, respectively, reflecting fast cooling (≥76°C/m.y.) until the solidus was attained at ca. 680°C. Under these conditions, the quartzmonzodiorite was cut by a spessartite sill, which yielded a U-Pb titanite age at 342.0 ±1.0 Ma. Fast migration of contact melt into shrinkage cracks of the sill resulted in thin felsic veins.

Bulk constriction at T = ca. 660°C led to (1) subvertical prolate grain-shape fabrics, (2) increase of the sill’s dip, (3) doubling of the sill’s thickness, (4) mullions with cusps pointing into the host, and (5) boudinage of the felsic veins. The shape of the mullions, the boudinage of the felsic veins and the sigmoidal foliation/lineation indicate that the mafic sill was incompetent and the felsic material of host and veins was competent. This inversion in rheology can be explained by phase-boundary diffusion that was more effective in the fine grained mafic sill than in the coarse grained felsic host.

Funding by Deutsche Forschungsgemeinschaft (Zu73-35) is acknowledged.

References

Zulauf, G. et al. (2021). Development of a synorogenic composite sill at deep structural levels of a continental arc (Odenwald, Germany). Part 1: Sederholm-type emplacement portrayed by contact melt in shrinkage cracks. Tectonophysics, 805 and (2022). Part 2: Rheological inversion and mullion formation under bulk constriction. J. Struct. Geol., 155



MON: 25
Topics: 4.5 Tectonic Systems (TSK Open Session)

U-Pb zircon geochronology of the Siebengebirge Volcanic Field - Implications for the dynamics of the Lower Rhine Basin (Germany)

Frank Tomaschek1, Severin Zumkeller1,2, Leoniedas Reschke1,3, Sascha Sandmann4, Markus Lagos1

1Institut für Geowissenschaften, Universität Bonn, Germany; 2Institut für Geologie und Mineralogie, Universität zu Köln, Germany; 3Physikalisches Institut, Universität Bonn, Germany; 4Geologischer Dienst Nordrhein-Westfalen, Krefeld, Germany

The Oligocene Siebengebirge Volcanic Field (SVF) is located at the south-eastern termination of the extensional Lower Rhine Basin (LRB). Tuffitic deposits, repeatedly embedded within the siliciclastic basin sediments, provide a largely untapped record on the evolution of intracontinental volcanism and basin dynamics. With the aim to provide radiometric age constraints, we applied laser-ablation U-Pb zircon geochronology on trachytic rocks from Siebengebirge surface outcrops, and tuffitic layers within drill cores of the Köln Formation.

While the lithostratigraphic sequence of the LRB is perfectly established [1], previous attempts using K-Ar on trachyte tuff sandine returned conflicting results, possibly due to diagenetic alteration [2]. Sampled tuffitic layers within the Oligocene of the Köln Formation (archived drill cores Haus Ölgarten and Niederpleis, GD NRW) returned U-Pb zircon populations from the Horizons 05/06 transition, as well as from Horizon 08 to Horizon 1, that are identical to those from the Siebengebirge trachytic outcrops.

In accord with previous results from Ar-Ar sanidine [3], U-Pb zircon geochronology confirms that differentiated volcanism in the SVF is restricted to a single, relatively short time period. First results for the Köln Formation suggest that the trachytic volcanism should indeed be placed at the base of Horizon 06 within the lithological standard profile, whereas similar material in younger horizons had probably been reworked. As a consequence, the voluminous trachytic SVF volcanism seems to coincide with accelerated subsidence of the rift basin.

[1] Schäfer et al. (2004) Newsl Stratigr; [2] Todt & Lippolt (1980) J Geophys; [3] Przybyla et al. (2018) IJES.



MON: 26
Topics: 4.5 Tectonic Systems (TSK Open Session)

U-Pb dating of fluid interactions: Hidden tectonic events in the Telemark domain (southern Norway)

Deniz Öz1, Frank Tomaschek1, Ronald Werner2, Markus Lagos1, Thorsten Geisler1

1Rheinische Friedrich-Wilhelms-Universität Bonn, Germany; 2Evje og Hornnes geomuseum Fennefoss, Postboks 24, N-4748 Rysstad, Norway

Regional tectonic events are difficult to detect in a stable continental crust, especially in the absence of major tectonic structures. Tectonic events may, however, trigger crustal fluid migration, leading locally to the formation of alterations zones in uraninite and uranium-bearing minerals. Accordingly, these events may be assessed, for example, by U-Th-Pb dating.

The Evje-Iveland pegmatites intruded at the end of the Sveconorwegian orogeny into the metamorphic basement of the Telemark tectonic domain of southern Norway. After magmatic crystallization, several fluid interactions lead to the alteration of igneous minerals and to the formation of discrete secondary mineral assemblages. We investigated uraninite and secondary uranium-phases from a range of Evje-Iveland pegmatite localities.

Pegmatites in the Landsverk area have been subjected to a prominent hydrothermal brecciation event, leading to the crystallization of hydrothermal minerals, including quartz, albite, epidote and titanite assemblages. A broad age group around 500 Ma is also obtained from hydrothermally altered domains of the Einerkilen uraninite. In addition, secondary uranium phases uranophane-β and uranophane yield chemical ages corresponding to the Early Cretaceous and Paleogene. The post-Sveconorwegian mineralisation can tentatively be related to the Caledonian orogeny, opening of the North Sea rift system, and Scandinavian uplift, respectively.

Distinct age populations from hydrothermally overprinted uranium ores can be correlated with regional tectonic events, not otherwise detected in a stable continental crust.



MON: 27
Topics: 6.1 Earth surface processes in extremely water-limited environments

Palaeomagnetic analyses in the Atacama Desert - challenges and chances

Stephanie Scheidt, Volker Wennrich, Patrick Grunert, Jassin Petersen, Pritam Yogeshwar, Martin Melles

University of Cologne, Germany

Magnetic polarity stratigraphy and magnetic palaeointensity stratigraphy is often used on sedimentary rocks to correlate outcrops and establish chronologies. The concept is based on the assumption that dipolar geomagnetic variations are globally synchronous and independent of climate and depositional conditions. The strengths of the method include the wide dating range and the applicability to a large variety of sediments and rocks. Best results are gained if long continuous sequences with high and uniform sedimentation rates are available. In the Atacama Desert, however, these perfect conditions are rare, as the landscape is strongly influenced by tectonic processes and extreme climatic conditions. Within the CRC1211 “Earth Evolution at the Dry Limit” magnetic stratigraphy is used to improve the age control of long drill cores from the claypans PAG, Huara, and Paranal, and of discrete samples from the marine Bahia Inglesia Formation. In addition, a first methodological attempt is being made to validate the potential of gypsum wedges as possible palaeomagnetic archive. The analyses are particularly carried out in order to specify the time covered by these geoarchives. Challenges for the palaeomagnetic analysis of the different archives arise from the often quite brittle nature of the unconsolidated sediments, the weak magnetizations and the complex magnetic mineralogy, potentially biased by diagenesis. Here we present challenges of the ongoing studies, as well as first results and perspectives.



MON: 28
Topics: 6.1 Earth surface processes in extremely water-limited environments

Geomorphological significance of the Atacama Pediplain as a marker for the climatic and tectonic evolution of the Andean forearc

Sebastián Muñoz-Farías1, Benedikt Ritter2, Tibor J. Dunai2, Jorge Morales-Leal1, Eduardo Campos1, Richard Spikings3, Rodrigo Riquelme1

1Departamento de Ciencias Geológicas - Universidad Católica del Norte, Av. Angamos 0610, Antofagasta, Chile; 2Institute of Geology a. Mineralogy – University of Cologne, Zülpicher Str. 49b, 50674 Cologne, Germany; 3Departament of Earth Sciences – University of Geneva, 13 Rue des Maraichers, Geneva, Switzerland

The Atacama Pediplain (AP) is a major element in the Atacama Desert landscape, commonly used as an indicator of climatic and tectonic stability. We choose the El Salado Canyon area (26°S) that longitudinally exposes the AP to study its relationship with the Andean forearc evolution, combining geomorphologic and stratigraphic observation with new geochronological data (40Ar/39Ar biotite ages on ignimbrites, and 21Ne exposure ages on quartz-clasts). The AP alluvial deposition occurred in two episodes of alluvial backfilling spatially and temporally separated from each other (Early Miocene - Mid Miocene in the Precordillera, and Mid Miocene - Early Pliocene in the Central Depression), and both triggered by semiarid to arid conditions restricted to the higher Precordillera. Both episodes occurred despite the regionally recorded Mid Miocene onset of hyperarid conditions, revealing the local control of the upstream humidity in the downstream sedimentation. Clustered exposure ages from the Pliocene reveal the abandonment of the alluvial plains due to the incision of the El Salado Canyon, whereas younger and individual exposure ages from the Early Pleistocene, explained by minor surficial activity, reveal a climatic control on the surfaces after the incision that ended with the increase of the Pleistocene hyperaridity. Therefore, the development of alluvial deposition despite the regional Mid Miocene hyperaridity, and the development of a deep canyon incision after the last recorded Andean uplift, reveals that the AP has been strongly influenced by local conditions that do not allow its use as a general marker of a single climatic or tectonic event.



MON: 29
Topics: 6.1 Earth surface processes in extremely water-limited environments

River evolution in the Atacama Desert: comparisons of cosmogenic nuclide and molecular clock dating approaches

Ariane Binnie1,2, Ambrosio Vega Ruiz3, Pia Victor3, Katrin P. Lampert4, Klaus R. Reicherter1, Gabriel Gonzalez5, Laura Evenstar6, Steven A. Binnie2

1Neotectonics und Natural Hazards Group, RWTH Aachen University, Germany; 2Institute of Geology and Mineralogy, University of Cologne, Germany; 3Helmholtz Centre Potsdam, GFZ German Research Center for Geosciences; 4Institute of Zoology, University of Cologne, Germany; 5Departamento de Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile; 6School of Environment and Technology, University of Brighton, UK

The Atacama Desert in northern Chile is considered to be the driest, oldest desert on Earth. None-the-less, even the hyperarid core of this desert is host to several deeply incised, fluvially active river canyons. The history of these drainages is tied to the tectonic and climatic evolution of the region, however, the timing and hence the mechanisms driving canyon formation are poorly constrained.

We have used cosmogenic 10Be exposure ages to define the Quaternary incision history for the southern tributary of the Tiliviche River, which exits to the Pacific approximately 19.5°S. Ages from flights of fluvial fill-cut terraces at two separate locations are consistent and suggest this branch of the river formed shortly after 2 Myr ago by relatively slow fluvial incision. This slow incision persisted until around 300-400 kyr ago, whereupon rates of downcutting increased by around an order of magnitude.

In this contribution, we discuss how the timing of the Tiliviche River incision rate increase may relate to tectonic mechanisms, both local faulting and with regards to proposed increases in regional scale crustal uplift. We include exposure ages from several proximal sites and suggest linkages between these events and the Tiliviche River evolution. Lastly, our project aims to compare the results from cosmogenic nuclide dating with fluvial histories derived from the timing of amphipod speciation. Our initial results show that there is much potential in combining cosmogenic nuclide approaches with molecular clock dating and implies river evolution in this area is controlled by a common, regional-scale process.



Application for Ramdohr Award in Poster session on Monday
MON: 30
Topics: 6.1 Earth surface processes in extremely water-limited environments

CaSO4 crust as potential habitat for microbial life in the extreme hyperarid Atacama Desert and their reciprocal effects

Lina Raffelsiefen, Aline Zinelabedin, Benedikt Ritter, Helge Mißbach-Karmrodt, Christine Heim, Tibor J. Dunai

Institute of Geology and Mineralogy, University of Cologne, Germany

The Atacama Desert is one of the most extreme landscapes and environments on Earth. Due to its predominant hyperarid climate and high UV radiation, life is mostly absent. Prolonged aridity causes the formation of CaSO4-rich soils and crusts from mostly atmospheric deposition and aeolian input, creating a blanket covering vast landscapes. Water as the defining pre-requisite for life is scarce, however, infrequent precipitation events, fog and dew are potential moisture sources. CaSO4-rich soils in the Atacama Desert are cemented due to secondary modification (dissolution, transport and re-precipitation) of CaSO4 minerals (Gypsum-Basanite-Anhydrite) and other soluble salts, which form an indurated surface cover with several dm to meters thickness. Within these CaSO4-rich soils, cavities and cracks are partly covered with recrystallized evaporitic minerals indicating the temporal presence of water activity (of unknown state and volume). Harsh environmental conditions on the surface contrast life in the subsurface. Microbial communities from different groups of bacteria, archaea and eukaryotes inhabit such endolithic environments, living from captured moisture within the soil, or potential from hydrated CaSO4. Their presence and interaction, however, can also influence pedogenic processes, contributing to CaSO4 dynamics as landscape forming agent and as preconditions for higher developed life. We present some initial results from a CaSO4-rich soil crust study from the Atacama Desert, using XRD, ICP-OES, and SEM imaging along with the lipid-biomarker analysis to explore and characterize the CaSO4-rich soil as habitat for microbial life, and to unravel the potential impact of microbial life on landscape forming processes, i.e. CaSO4 soil dynamics.



MON: 31
Topics: 6.1 Earth surface processes in extremely water-limited environments

The struggle of choosing the “best” data basis for remote geomorphological analyses – Quality assessment of open-source digital elevation models in Northwest Namibia

Julian Krieger, Janek Walk, Frank Lehmkuhl

Department of Geography, RWTH Aachen University, 52056 Aachen, Germany

Today, digital elevation models (DEM) form the data basis for most geomorphological analyses. With the wide range of freely available, global DEMs, the question arises which option is the best choice for the desired analysis. The quality of DEMs of equal spatial resolution can be characterized by their vertical accuracy and precision. While the vertical accuracy describes the one-dimensional difference between the DEM and the Earth’s surface, the precision describes the spatial error distribution within the dataset.

To study the geomorphologic evolution at the dry limit, the sparsely vegetated Northwest of Namibia provides a promising landscape due many ephemeral rivers incised differently far into the geologically complex Kunene Highlands and draining towards the Skeleton Coast, which is covered to a large extent by dune fields. This versatility, however, provides challenging condition for the assessment of DEMs, strongly dependent on the respective underlying remote-sensing technology. For this reason, we conducted a quality assessment of the commonly used SRTM, ASTER, ALOS and GLO-30 DEMs – all featuring an equal spatial resolution of one arc-second (~30 m). The absolute vertical error has been assessed by validation using geodetic ICESat-2 data. To quantify the precision of the DEMs in relation to the morphometric complexity of the terrain, surface roughness measures were applied. In addition, it was investigated whether the lithology has an impact on the accuracy and precision. In conclusion, the GLO-30 turned out to be as yet the most accurate (RMSE = 1.1 m) and precise open-source DEM for Northwest Namibia.



MON: 32
Topics: 6.1 Earth surface processes in extremely water-limited environments

TephATA: A Tephrostratigraphic Framework for the Atacama Desert and its Application on Regional Sedimentary Archives

Niklas Leicher1, Volker Wennrich1, Bernd Wagner1, Dirk Hoffmeister2, Tanja Kramm2, Vincent Feldmar2, Georg Bareth2

1Institute of Geology and Mineralogy, University of Cologne, Germany; 2Institute of Geography, University of Cologne, Germany

A fundamental aspect to study past Earth surface process variations over time and to set local observations in a regional and global context is their temporal understanding. However, accurate dating of sedimentary archives documenting these variations can be hampered in extremely water-limited environments by applicable dating methods (type of archive/temporal range). Tephrostratigraphy and -chronology can be applied independent of the type of sedimentary archive and thus represent powerful tools for dating and synchronization of archives. In the Atacama Desert, tephra layers occur in various types of archives and on various time‑scales. A tephrostratigraphic framework, which sets the tephra layers in a stratigraphic and chronological order and shows the regional dispersal of individual tephra layers is currently lacking. Within the CRC1211 “Earth-Evolution at the dry limit”, the project TephATA aims at setting up a regional tephra database to develop the first comprehensive tephrostratigraphic framework for the Atacama. The database TephATA is currently integrated as a web-based part of the CRC1211 database and uses an extended IGSN metadata schema. TephATA combines existing and new chronological as well as stratigraphical information of tephra layers with their glass geochemical compositions, which is the backbone for reliable correlations of tephra layers and identification of widespread marker horizons. If the geochemistry-based approach allows a correlation of tephra layers, age information can be transferred to tephra layers that does not contain sufficient minerals for absolute dating. Particularly widespread tephra layers will function as independent tie-points for the synchronization of the various sedimentary records investigated within the CRC1211.



MON: 33
Topics: 6.1 Earth surface processes in extremely water-limited environments

A 16 ka record of high-amplitude precipitation events from the southern part of the hyperarid Atacama Desert.

Volker Wennrich1, Marlene Lenz1, Mark Reyers2, Jan H. Schween2, Florian Kerber3, Katharina Walber-Hellmann1, Bárbara Vargas-Machuca A.1, Dirk Hoffmeister4, Simon Matthias May4, Joel Mohren1, Benedikt Ritter1, Tibor Dunai1, Martin Melles1

1University of Cologne, Institute of Geology and Mineralogy, Cologne, Germany; 2University of Cologne, Institute of Geophysics and Meteorology, Cologne, Germany; 3ESO, European Southern Observatory, Garching, Germany; 4University of Cologne, Institute of Geography, Cologne, Germany

The Atacama Desert in Chile is known to be one of the driest deserts on Earth, with dominating hyperaridity since the Miocene. During recent times, however, especially the southern part of the Atacama repeatedly experienced exceptional precipitation events, like in 2015 and 2017. Locally, these events with rainfall rates of >50 mm within 48 hours caused catastrophic floods with significant destruction and human fatalities. Although the meteorological drivers of these heavy rains are widely understood, only little is known about the frequency and amplitude of similar events on geological timescales.

Here we present the results of a study in an endorheic claypan from the southern edge of the hyperarid core of the Atacama, an area with mean annual precipitation of 5 mm/a. A modern ground-truthing approach applying remote-sensing and meteorological as well as climate-modelling data indicate that during the past 30 years, the claypan reacted very sensitive to local precipitation, with events >20 mm of rain causing sufficient surface run-off in the catchment to partially flood the basin. A short sediment core recovered from the center of the claypan covers approx. the past 16,000 years. First sedimentological, mineralogical, and geochemical findings imply strong variations in the amplitude of the recorded precipitation events over time, with a clear shift from more intense to lower-amplitude events from the late Pleistocene to the Holocene. The results of the study shed new light on the glacial-interglacial precipitation variability in the Atacama Desert and its driving mechanisms.



MON: 34
Topics: 6.1 Earth surface processes in extremely water-limited environments

Deciphering the Gypsum - Anhydrite Phase Transition in the Atacama Desert

Niklas Wehmann, Christoph Lenting, Sandro Jahn

University of Cologne, Germany

Present as gypsum (CaSO4∙2H2O), bassanite (CaSO4∙0.5H2O) and anhydrite (CaSO4), calcium sulphates comprise a significant fraction of the surface and soil in the Atacama Desert.
Field observation suggest a secondary formation process for the dehydrated sulphates.
These thermodynamically predicted phase transitions were ruled out by previous studies to occur by heating under ambient conditions of the Atacama Desert or by suppressing the water activity with simplified brine-solutions[1]. Furthermore, high induction times for nucleation hampers anhydrite growth.
Recent studies[2,3] have shown that precipitation of anhydrite can be achieved in flow-through reactors at room temperature even with high water-activity (aw = 0.98).
Results from our own flow-through experiments with gypsum seeded with anhydrite under a variety of temperatures and salinities contradict the notion that the production of anhydrite is a consequence of simple hydrological factors. It appears essential to gain a deeper understanding of catalytic processes that stabilize anhydrite nuclei.
Possible responsible catalysts could be of ionic, nano-particulate or organic nature. The effects of these catalysts have been studied in the literature extensively[4] and especially nanoparticles and ions from soluble salts are abundant in Atacama Desert sediments.
We show results from experiments performed on natural and synthetic samples that systematically explore the domains of solution flow, ionic contamination and nanoparticles.

[1] Ossorio, M., et al., Chemical Geology 386 (2014): 16-21.
[2] Dixon, E., et al., Journal of Geophysical Research: Planets 120.4 (2015): 625-642.
[3] Miller, Kayla., (2017).
[4] Cody, R. D., and A. B. Hull., Geology 8.10 (1980): 505-509.



MON: 35
Topics: 6.1 Earth surface processes in extremely water-limited environments

A new experimental approach for the determination of the diffusivity fractionations of water isotopes in air

Mohammed El-shenawy, Daniel Herwartz, Michael Satubwasser

University of Cologne, Germany

Water isotopes are key tools to understand the dynamics of the global hydrological cycle. A well constrained hydrological model requires a precise definition of isotopic diffusion and equilibrium fractionation factors (DIFF and EIFF, respectively) among water phases. Although there is a consensus on the EIFFs in the community, there is still a debate regarding the precise DIFF. Few experimental studies were performed to define the DIFFs of water in air, however, their data are scattered significantly. Most of these experiments were designed to gradually evaporate a small body of water forced by a stream of either dry nitrogen or air. This design induced several complications, including turbulence, surface cooling and isotopic heterogeneity in the water body, which required additional steps of corrections that may affect the final calculation of the DIFF.

In this study, we performed a passive approach using a hygroscopic salt (Anhydrous CaCl2) to absorb water vapor from air (nitrogen) under controlled relative humidity at room temperature in a glove box. Once the CaCl2 granules exposed to humid air, it progressively absorbed water vapor until it dissolved into the water forming a brine. At the early stage of the absorption the thin water film upon the surface of CaCl2 reflects a pure isotopic diffusion of water vapor, while the final stage of absorption (i.e., brine) represents a pure isotopic equilibrium between water vapor and the brine. Hydrogen and oxygen isotope measurements of these two stages of absorption will be presented in the meeting.



MON: 36
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

The new Cologne Noble Gas Laboratory – Extraction and Analysis of cosmogenic Ne Isotopes

Benedikt Ritter, Andreas Vogt, Tibor J. Dunai

University of Cologne, Institute of Geology & Mineralogy, Germany

We established a new laboratory for noble gas mass spectrometry that is dedicated to the development and application to cosmogenic nuclides at the University of Cologne. At the core of the laboratory are a state-of-the-art high-mass-resolution multicollector Helix MC Plus (Thermo Fisher Scientific) noble gas mass spectrometer and a novel custom-designed automated extraction line. The mass spectrometer is equipped with five combined Faraday multiplier collectors, with 1012 and 1013 Ω preamplifiers for faraday collectors. We installed and build up a new extraction line to conduct Ne isotope analysis, including laser extraction and cryogenic automated separation. Except for the laser, the extraction process is completely automated and allows a high standard of reproducibility, which prevents variations due to manual operation. Performance tests were conducted using gas of atmospheric isotopic composition (our primary standard gas), as well as CREU‑1 intercomparison material, containing a mixture of neon of atmospheric and cosmogenic composition. The precision in determining the abundance of cosmogenic 21Ne is equal to or better than those reported for other laboratories. The absolute value we obtain for the concentration of cosmogenic 21Ne in CREU is indistinguishable from the published value. We now regularly perform analysis of samples for cosmogenic neon for running projects and are open to new collaborations. For further information we refer to our publication Ritter et al. 2021 - Technical Note: Noble gas extraction procedure and performance of the Cologne Helix MC Plus multi-collector noble gas mass spectrometer for cosmogenic neon isotope analysis – Geochronology - https://doi.org/10.5194/gchron-3-421-2021



MON: 37
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

Weathering geochronology of a deep (> 120 m) lateritic profile in northern Brazil

Beatrix Heller1,2, Thierry Allard2, Caroline Sanchez1, Guilherme Taitson Bueno3, Jean-Yves Roig4, Cécile Gautheron1

1GEOPS, Université Paris-Saclay, CNRS, France; 2IMPMC, Sorbonne Université, CNRS, IRD, MNHN, France; 3Universidade Federal de Goiás, Brazil; 4BRGM, France

Tropical weathering leads to the formation of deep weathering profiles called laterites. The Guiana shield has been tectonically stable and in tropical latitudes supposedly since the Cretaceous, allowing the formation of very deep (> 100 m) and old (tens of Ma) lateritic profiles.

In this contribution we present a coupled data set of kaolinite electron paramagnetic resonance (EPR) ages and (U-Th)/He ages of supergene hematite and goethite from a deep (> 120 m) weathering profile exposed in an open pit gold mine in the northern Brazilian state of Amapá. Coupling of the two methods which target different components of the lateritic profile allows us to reconstruct the formation and evolution of the presented profile throughout the entire Cenozoic. While (U-Th)/He ages on supergene hematite and goethite from the ferruginous duricrusts on the top of the profile record three discrete weathering events during the Late Cretaceous/Early Paleocene, Oligocene and Middle Miocene, kaolinite ages allow an insight into the vertical evolution of the profile. The oldest kaolinites, which are very well-ordered, are preserved in the saprolitic part of the profile whereas the kaolinites in the top of the profile show very recent (< 5Ma) rejuvenation. Disordered kaolinite captured in the lateritic duricrust was protected from this rejuvenation.



Application for Ramdohr Award in Poster session on Monday
MON: 38
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

Deriving basin-wide erosion/denudation rates of basaltic rocks using cosmogenic Kr isotopes, vulcanic complex Vogelsberg, Germany

Sabrina Niemeyer, Joel Mohren, Tibor J. Dunai

University of Cologne, Institute of Geology and Mineralogy, Germany

The Vogelsberg area located in Hessen, Germany, comprises the largest contiguous volcanic complex in Central Europe, covering an area of about 2300 km². After volcanic activity ceased during the Mid Miocene, the complex was subject to extensive erosion and weathering. Fluvial erosion has shaped the area, which is now characterised by Pleistocene valleys and a radial river system exposing primitive alkali basalts and basanites. The inference of time-integrated erosion rates from regularly measured cosmogenic nuclides (e.g. 10Be, 26Al) remains challenging in such an environment due to the apparent mafic and thus quartz-poor composition of the local bedrock. However, the application of cosmogenic Kr isotopes on the weathering-resistant mineral zircon provides a novel tool to infer basin-wide denudation rates from quartz-poor lithologies. In our project, we aim to exploit the advantage of the applications of Kr and sample zircons from sediments of six streams radially draining the Vogelsberg. After zircon purification, these samples will be measured at the Cologne Noble Gas Mass Spectrometer to quantify Kr concentrations in these samples and to assess the time-integrated erosion patterns shaping the volcanic complex.



MON: 39
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

Towards a more robust assessment of internal K-content for single-grain feldspar luminescence dating.

Linda Maßon, Svenja Riedesel, Anja Zander, Tony Reimann

University of Cologne, Germany

Accurate dose rate determination is essential in luminescence dating studies and when using feldspars, the internal K-content has to be considered. Until recently it was common practice to base the estimates for the internal content of 40K and 87Rb of feldspar extracts used for infra-red stimulated luminescence dating on literature values. However, in some regions of the world (e.g. Atacama, Java), feldspar extracts prepared for single-grain luminescence analyses exhibit a complex mineralogy affecting the reliable determination of the internal dose rate (e.g. Sontag-González et al., 2021). A proof of concept study on luminescence dating in the central Atacama Desert for example demonstrated that values suggested by literature overestimate the K-content of the luminescent feldspars (Zinelabedin et al., 2022).

Here we test and evaluate different methods to determine the K-content of feldspar grain separates and its impact on single grain luminescence dating. For a set of chemically and structurally different samples from various geological origins, we compare the labour-efficient determination of the K-concentration on 100 µg subsamples utilising a β-counter with two more time-consuming techniques (EDX, micro-XRF) measuring the K-content of the individual grains.

We test the validity of the time- and cost-efficient β-counter dose rate estimation procedure in comparison to more cost- and labour-intensive alternatives. We aim at establishing a methodological foundation for spatially-resolved and single-grain luminescence-based analysis of feldspar samples with the ultimate goal to investigate geomorphological processes on the μm-scale in the Atacama Desert.

References:

Sontag-González et al. 2021, QG 65, 101181.

Zinelabedin et al. 2022, QG 101341.



MON: 40
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

A multi-methodological approach to investigate the erosion of arable land caused by the July 2021 flood event in Erftstadt-Blessem, Germany

Joel Mohren, Steven A. Binnie, Matthias Ritter, Tabea Kautz, Sabine Tiegelkamp, Tibor J. Dunai

Institute of Geology and Mineralogy, University of Cologne, Germany

Severe flooding in July 2021 has caused massive erosion of arable land located close to the village of Erftstadt-Blessem, Germany. Backward incision formed local drainage networks, evacuating Quaternary sediments towards a gravel pit located to the north of the village. The fluvially shaped topography was largely preserved after the flooding, providing the opportunity to characterise the mode of erosion and to identify factors that governed the manifestation of processes involved. The presence of somewhat exotic erosive features (e.g. amphitheatre-shaped channel heads, natural pipes) leads us to the hypothesis that groundwater sapping could have played a major role in eroding the arable land and underlying sediments. To test this hypothesis, we use Structure-from-Motion Multi-View Stereo photogrammetry to reconstruct drainage geometries (drone imagery provided by the Kreisverbindungskommando Köln, M. Wiese; supported by T. Gersthofer, ESRI Deutschland GmbH) and for in-situ density measurements of subsurface layers. Subsurface characteristics are further assessed by grain size analyses and X-ray diffractometry. The data are used to compare the post-flood topography of Erftstadt-Blessem to sapping-shaped topography on Earth and Mars. Furthermore, 239+240Pu activities are measured in pipe infills to investigate hypothetical spatial connections to the uppermost soil horizons. Burial dating techniques (cosmogenic 26Al/10Be and optically stimulated luminescence) are used to constrain the age of the eroded sediments. Our overarching goal is to use our data as input for landscape evolution modelling to assess the importance of individual factors (e.g. substrate properties, vegetation cover) on the severity of erosion in Erftstadt-Blessem and comparable settings.



MON: 41
Topics: 6.2 Rates and Dates of Earth Surface processes: Methods & Applications

Applications of fallout plutonium at the University of Cologne to resolve Anthropocene Earth (sub-)surface processes

Joel Mohren1, Steven A. Binnie1, Erik Strub2, Stefan Heinze3, Tibor J. Dunai1

1Institute of Geology and Mineralogy, University of Cologne, Germany; 2Division of Nuclear Chemistry, University of Cologne, Germany; 3CologneAMS, Institute of Nuclear Physics, University of Cologne, Germany

Anthropogenic fallout radionuclides (FRNs), in particular 137Cs, are frequently measured to investigate Anthropocene sediment or soil particle redistribution patterns and rates. However, applications of 137Cs can be complicated due to contaminations from nuclear power plant accidents. In addition, decreasing global 137Cs activities mean that it will become increasingly difficult to measure in coming decades. Fallout 239+240Pu measured by Accelerator Mass Spectrometry (AMS) remains largely unaffected by these issues and allows more precise measurements on smaller sample sizes. There is thus much potential for 239+240Pu in modern Earth (sub-)surface processes investigations. The Institute of Geology and Mineralogy, together with the Division of Nuclear Chemistry, and the Centre for Accelerator Mass Spectrometry (CologneAMS), University of Cologne, have developed 239+240Pu capabilities, calibrated against published and externally referenced in-house standards. Measurement uncertainties regularly achieved are < 5%. Based on these preconditions, we now aim to comprehensively exploit the wealth of possible 239+240Pu applications to decipher modern Earth (sub-)surface processes. We present a selection of ongoing projects, in which we assess deflation processes (South Africa, northern Chile), aspect-induced differential soil erosion (central Chile), seismic-induced boulder slip rates (northern Chile), and sediment transport through natural pipes associated with sapping processes (Germany). Furthermore, we test the application of 239+240Pu as proxy for rainfall in the Atacama Desert (northern Chile). Our approaches contribute to a better understanding of Earth (sub-)surface processes in the Anthropocene, and, where applicable, we seek to compare these data to longer-term background rates of topography formation.



MON: 42
Topics: 6.4 Landslides – detecting, monitoring, modeling, assessing hazards, and coping with risks

Towards high efficacy Early Warning in Europe

Andreas Nikolaus Küppers

The Potsdam Conventus

Early Warning Systems for natural disasters are the most promising means of saving lives, property and societal integrity in cases of impending natural hazards. They are expected to be critically required, even more in the future, as either new and hitherto unknown phenomena are expected to become substantial threats, or climate change brings increasing intensity, impact and frequency of adverse weather related phenomena, or cascading hazardous processes appear more frequently. Since the 1994 Yokohama World Conference on Disaster Risk Reduction, Early Warning Systems are acknowledged as the most efficient elements of societal resilience, however the ‘State of the Global Climate 2021’ (World Meteorological Organization, WMO, 2022) concludes the very low implementation level and often extremely poor performance of existing systems. In order to foster the implementation and improvement of systems in all 193 Member States, the United Nations have declared the coming five years as ‘Years of Early Warning ‘. Based on a broad range of practical and organizational experiences from 1980s events in Japan, the Yokohama World Conference, the 1998 Potsdam Early Warning Systems Conference, several successful scientific and technical development projects financed by the European Union, this contribution delivers an architectural design structure as well as a comprehensive roadmap for Early Warning implementation in Europe. It encompasses the necessary steps in national and international policies, in diverse fields of legislation, in various involved scientific and technical disciplines, and in the harmonization of ethical approaches. The creation of a European Centre for Early Warning Information is suggested.



MON: 43
Topics: 6.4 Landslides – detecting, monitoring, modeling, assessing hazards, and coping with risks

Comparing data-driven landslide susceptibility mapping methods and the impact of modifying the study area and sampling method in the Hunza Valley (Pakistan)

Nick Schüßler, Jewgenij Torizin

Federal Institute for Geosciences and Natural Resources, Germany

We compared artificial neural networks (ANN), frequency ratio (FR), logistic regression (LR), and weights of evidence (WoE) for landslide susceptibility mapping in the Hunza Valley, Pakistan. We applied different data manipulation techniques (e.g. feature masking and sampling) to analyze their effects on the model. The landslide inventory was collected using Google Earth satellite images. The corresponding potential causative factors were derived from a geological map, a digital elevation model, and satellite imagery data. We evaluated the models with receiver operating characteristics curves using cross validation. Using the validation data, ANN showed the best performance, followed by LR, WoE, and FR. All applied procedures achieved good and comprehensible results. However, the susceptibility patterns show substantial differences. Modifying the study area (e.g. excluding trivial areas, such as glaciers) and using different sampling strategies significantly impacts the susceptibility patterns in all models. We recommend the use of WoE and FR in large areas with few causative factors, despite their lower performance, as their models are more robust in areas with few observations compared to LR and ANN. ANNs unfold their potential for landslide susceptibility mapping only completely in areas with many non-linear correlated continues data sets, where they are superior to other methods. Modifying the study area and sampling technique can have a bigger impact on the final susceptibility model than using another data-driven landslide susceptibility mapping method.


MON: 44
Topics: 6.4 Landslides – detecting, monitoring, modeling, assessing hazards, and coping with risks

A Review and Database of Landslide Induced Tsunamis

Katrin Dohmen, Anika Braun, Tomás Manuel Fernandez-Steeger

Technische Universität Berlin, Germany

Landslide induced tsunamis are a well-known phenomenon and have been reported many times in the international literature. The research has focused so far on the investigation of individual case studies and on modelling of tsunami waves but up to now there is no overview of all documented landslide tsunamis that happened in the past and what might be learned from those events.

The objective of this study is a review and comparison of the known case studies. A database of parameters that are relevant for the tsunami generation and propagation is established. Those include the properties of the landslide, the waterbody geometry and tsunami properties.

Particularly high waves can be triggered when slopes collapse and fall into waterbodies with little water volume like rivers, lakes or narrow bays that are widely isolated from the open sea. Catastrophic landslide tsunamis occur frequently in fjord landscapes with elongated and narrow waterbody geometries with steep and - due to deglaciation processes - instable slopes. Also, in seismically active regions where earthquakes can trigger landslides, many landslide tsunamis have been reported. A third scenario with an especially high potential for landslide tsunamis are reservoir lakes, where seasonal water level variations may cause slope instabilities.

The findings of this work will contribute to a better understanding of the generation of landslide tsunamis. They can be used in a next step to identify potentially endangered areas and to take preventive measures regionally, for example to set up monitoring systems on slopes at risk.



MON: 45
Topics: 7.2 Living Earth – geobiological perspectives on an evolving planet

Fossilization of Precambrian microfossils in the Volyn pegmatite, Ukraine

Gerhard Franz1, Peter Lyckberg2, Vladimir Khomenko3, Vsevelod Chernousenko4, Hans-Martin Schulz5, Nicolaj Mahlstedt5, Richard Wirth5, Johannes Glodny5, Ulrich Gernert6, Jörg Nissen6

1Technische Universität Berlin, Germany; 2Luxembourg Nat. Museum of History, Luxemburg; 3Nat. Acad. Sci. of Ukraine, Kyiv; 4Volyn Quartz Samovety Co., Khoroshiv, Ukraine; 5GFZ German Res. Centre Geosci., Potsdam, Germany; 6ZELMI at TU Berlin, Germany

The Volyn biota are a distinct and uncommon example of 3D-preservation of ~1.5 Ga old Precambrian fossils, recovered from cavities in pegmatites, which were the habitat for microorganisms in the deep biosphere. The Volyn pegmatite district is associated with the Paleoproterozoic Korosten Pluton, Ukraine. Breccias, formed during collapse of miarolitic cavities, contain decaying OM, which released NH4+, responsible for the late-stage formation of buddingtonite and tobelite-rich muscovite. The age of the fossils can therefore be restricted to the time between the pegmatite formation, at ~1.760 Ga (zircon U-Pb), and the breccia formation at ~ 1.5 Ga (muscovite Ar-Ar).

The organic matter (OM) is characterized as (oxy)kerite. Microanalytical investigations show that fossilization likely occurred during a hydrothermal, post-pegmatitic event, by silicification dominantly in the outermost 1-2 µm of the microfossils. The hydrothermal fluid, derived from the pegmatitic environment, was enriched in SiF4, Al, Ca, Na, K, Cl, and S. The OM shows O enrichment where N and S content is low, indicating simultaneous N and S loss during anaerobic oxidation. Mineralization with Al-silicates starts at the rim of the microfossils, continues in its outer parts into identifiable encrustations and intergrowths of clay minerals, feldspar, Ca-sulfate, Ca-phosphate, Fe-sulfide, and fluorite. As geological environment for growth and fossilization of the microorganisms we assume a geyser system, in which the essential biological components C, N, S, and P were derived from microorganisms at the surface. Fossilization was induced by magmatic SiF4-rich fluids.



Application for Ramdohr Award in Poster session on Monday
MON: 46
Topics: 7.2 Living Earth – geobiological perspectives on an evolving planet

Pressure anomaly of the ATP hydrolysis rate facilitates life of extremophiles

Christoph Moeller1, Christian Schmidt2, Denis Testemale3, Francois Guyot4, Max Wilke1

1Universität Potsdam, Germany; 2GeoForschungsZentrum, Germany; 3CNRS, Université Grenoble Alpes, France; 4IMPMC Muséum National d'Histoire Naturelle, France

Life is prevalent on Earth even in extreme environments, e.g., near black smokers. This biological community has to face temperatures of up to 120 °C and pressures of 40 MPa. To maintain vital reactions, extremophiles have developed varies mechanisms to survive. The stability of the energy-storing molecules adenosine triphosphate (ATP) and adenosine diphosphate (ADP) are of essential importance because reactions involving these phosphates constrain the range of life. ATP is limited by the non-enzymatic hydrolysis, which is kinetically enhanced at high temperatures. If this abiotic process is too rapid, metabolism as we know won’t be possible anymore. The effect of elevated temperatures on the hydrolysis rate constants of ATP is widely known and is best described by an Arrhenius relationship. In contrast to previous studies, our first findings showed a decelerating effect from 0 – 60 MPa with a minimum in the reaction rate at 20 – 40 MPa at 100 °C. The rate constants of the non-enzymatic hydrolysis of ATP are decreasing from 5.8 x 10-4 s-1 at 0.1 MPa to 4.2 x 10-4s-1 at 20 MPa at 100 °C. The corresponding half-lives are 1195 s and 20 MPa. This observation is extremely fascinating as Takai et al. (2008) have seen a similar pressure anomaly at extreme temperatures for Methanopyrus Kandleri.



MON: 47
Topics: 7.3 Assessment of the Earth System through Micropaleontology

Temperature calibration for high Mg-calcite planktic Foraminifera shells from the Gulf of Aqaba

Noy Levy1,2, Adi Torfstein2,3, Ralf Schiebel1, Natalie Chernihovsky2,3, Klaus Peter Jochum1, Ulrike Weis1, Brigitte Stoll1, Gerald H. Haug1,4

1Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany; 2The Fredy & Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem 91904, Israel; 3Interuniversity Institute for Marine Sciences, Eilat 88103, Israel; 4Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland

Hypersaline, oligotrophic seas have been shown to accommodate planktic Foraminifera (PF) with enriched Mg/Ca in their calcareous shells, compared to other marine environments. Although Mg/Ca is a widely used proxy applied as a paleothermometer, its systematics in extreme hypersaline systems is not well understood.

We measured element ratios using LASER ablation ICP-MS on the tests of the two abundant PF species, Globigerinoides ruber albus and Turborotalita clarkei, obtained from monthly resolved time series sediment traps at various water column depths in the northern part of the GOA.

Globigerinoides ruber albus shows a positive relationship between Mg/Ca and surface water temperatures of the surface mixed layer down to 60 m water depth. Although T. clarkei does not show the same positive relationship, it exhibits high Mg/Ca during water column mixing (March–April) possibly reflecting the movement of two water masses in the water column.

Using common calibration equations (Anand et al., 2003; Kisakürek et al., 2008; Gray et al., 2018), the high-Mg (5-25 mmol/mol) provided higher than measured in-situ (IS) ambient seawater temperatures (TMg/Ca and TIS, respectively). The high salinity at the GOA (>40) is assumed to be the main reason of the high shell-bound Mg.

Comparing surface dwelling G. ruber albus versus subsurface dwelling T. clarkei may facilitate reconstruction of the absolute and relative seasonal development temperature and surface water stratification. We suggest that species specific Mg/Ca-T calibrations for the GOA provide more accurate regional palaeoceanography and paleoclimate reconstruction of hypersaline environments.



MON: 48
Topics: 7.3 Assessment of the Earth System through Micropaleontology

Significance of millennial-scale coastal upwelling and Rio Loa variability for Atacama paleoclimate during MIS 2

Jessica Fabritius, Andrea Jaeschke, Jassin Petersen, Volker Wennrich, Patrick Grunert

Universität zu Köln, Germany

The Atacama Desert located in northern Chile is one of the driest places on earth. The factors determining recent hyperarid climate conditions are known and their interplay and variability on interannual and decadal time scales are generally understood. Evidence for wetter (yet arid) conditions in the Atacama’s past is provided by episodic lacustrine and fluvial deposits. The main watercourse of the Atacama Desert is the Rio Loa sourced by rainfall in the Andean mountains. Information on changes of terrestrial supply to the ocean is recorded in marine sediments.

The sediment core SO-104-52KL has been collected on the upper continental slope (∼340 m water depth, 21°S) off the Rio Loa during a cruise with RV Sonne. The preliminary age model based on 14C-dating constrains the top and base of the core to 16 and 42 ka, respectively. Very high average sedimentation rates will allow paleoceaonographic and paleoclimatic studies of high resolution (millennial to centennial time scales) during the last glacial period. The location of the core on the continental slope off the Rio Loa mouth allows for the parallel evaluation of the Humboldt Current System and Andean rainfall as moisture sources for the Atacama Desert. Microfossils such as benthic foraminifera from this interval are abundant and well-preserved. Together with XRF-data, grain-size and lipid biomarker analyses, the expected proxy data will provide new insights into the dynamics of land-ocean coupling between the Atacama Desert and the eastern Pacific Ocean through characterization of coastal upwelling properties and Rio Loa runoff.



MON: 49
Topics: 7.3 Assessment of the Earth System through Micropaleontology

Neoflabellina reticulata (Reuss 1851) – The Fossil of the Year 2022

Anna Charlotte Pint, Peter Frenzel

Institut für Geowissenschaften, Friedrich-Schiller-Universität, Jena Burgweg 11, 07749 Jena, Germany

The Paläontologische Gesellschaft (Palaeontological Association) has been awarding the title Fossil of the Year since 2008. Every year an important fossil is chosen to promote palaeontology in the public. This year, after presenting several vertebrate, invertebrate and plant fossils, a microfossil was selected for the first time. Arguments for the selection of the foraminifer Neoflabellina reticulata are:

- Neoflabellina reticulata is a beautiful fossil.

- Neoflabellina reticulata is an index fossil of the Maastrichtian, thus underlines the utility of microfossils in biostratigraphy. The Maastrichtian is the last stage of the Cretaceous and ends with the best known mass extinction event.

- Neoflabellina reticulata lived in marine shelf environments below the storm wave base, i.e., it can be used as palaeoecological indicator.

- Neoflabellina reticulata can be found in practically all chalk environments of the Maastrichtian and is documented from such well known sites as the chalk cliffs of Rügen island.

- The first description of Neoflabellina reticulata was published by August Emil Reuss in 1851, in the period of the establishment of micropalaeontology as a science.

- The locus typicus of Neoflabellina reticulata are the chalk marls of Lemberg, todays Lviv in Ukraine. This underlines the connectivity of science.

The Fossil of the Year was presented in a public lecture in the Pommersches Landesmuseum in Greifswald 22 May 2022. Here, we provide more information on our poster.



MON: 50
Topics: 7.3 Assessment of the Earth System through Micropaleontology

Neogene palaeoceanographic changes off northern-central Chile based on benthic foraminifera from the Bahía Inglesa Formation

Fatima Bouhdayad1, Laura Makowka1,2, Laura Schneider1, Tiago Freire1, Jassin Petersen1, Sven Nielsen3, Marcelo Rivadeneira4, Patrick Grunert1

1Institute of Geology and Mineralogy, University of Cologne, Germany; 2Universidad de Salamanca, Salamanca, Spain; 3Instituto de Ciencias de la Tierra, Universidad Austral de Chile, Valdivia, Chile; 4El Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile

The modern oceanographic setting off northern-central Chile is characterized by highly productive waters and an extensive Oxygen Minimum Zone (OMZ), both resultant from coastal upwelling induced by the Humboldt Current System. However, oscillations of upwelling and OMZ properties during the Neogene are still poorly understood. Here, we assess palaeoceanographic conditions based on benthic foraminifera assemblage data of marine sediments from the Bahía Inglesa Formation (Upper Miocene-Pliocene), recovered from the Quebrada Tiburón outcrop (27°42' S, 70°59' W). Quantitative paleoenvironmental analyses of benthic Foraminifera >250 µm from 6 samples are currently conducted. Preliminary results show shifts in both, the diversity and abundance of hyaline species over the studied interval. High abundances of planospiral (predominantly epifaunal) morphotypes in sandy, heavily bioturbated parts of the studied section alternate with diatom-rich sediments bearing predominantly serial (infaunal) taxa such as Bolivina aenariensis and Uvigerina peregrina/striata. The observed changes in assemblage composition imply significant changes in biological productivity, bottom-water oxygenation, and ultimately, coastal upwelling off Chile in the Neogene. Further refinements of the stratigraphic model for the studied section will clarify the timing of the here described preliminary observations of paleoenvironmental fluctuations. This study contributes to project A4 Land‐ocean coupling between the Humboldt Current System and Atacama palaeoclimate in the Neogene” of CRC 1211 “Earth-evolution at the dry limit”.



MON: 51
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Magma evolution and epithermal ore formation at Conical Seamount, Papua New Guinea

Louis-Maxime Gautreau, Philipp A. Brandl, Thor H. Hansteen

GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Germany

The Tabar-Lihir-Tanga-Feni (TLTF) island chain in northeastern Papua New Guinea hosts the world-class Ladolam gold deposit on Lihir island as well as several other Au prospects. Several young seamounts are located around Lihir and were studied in detail by three RV Sonne cruises in 1994, 1998 and 2002. While most of these seamounts are considered barren, Conical Seamount, located southeast of Lihir island, shows evidence for epithermal-style mineralization and has been interpreted as a submarine analogue to the Ladolam deposit. It offers a rare opportunity to study a porphyry-epithermal ore system at a juvenile stage and compare it to a mature system nearby.

In the first phase of our research project, we focus on the igneous system underlying the epithermal ore-forming system at Conical. We study the lavas as well as minerals and glass inclusions to reconstruct melting processes, magma evolution and ore fertility using detailed petrology, in situ geochemistry and thermobaric modelling. Special emphasis is given to volatile as well as trace metal and metalloid contents in bulk rocks, glasses and glass inclusions. Mineral zonations and the compositional diversity of pyroxene-hosted glass inclusions point towards repeated magma recharge and the potential existence of multiple magma stagnation levels. While the high melt oxidation state (∆ log fO2 of +0.5 to +2 relative to FMQ) at Conical is advantageous for the enrichment of chalcophile elements in the evolving melt, high volatile contents may promote early fluid exsolution and the transfer of metals and metalloids into the epithermal system.



MON: 52
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Re-distribution of platinum-group elements in supergene ores of the Merensky Reef, Eastern Bushveld Complex, South Africa

Maximilian Korges1, Malte Junge2, Gregor Borg3, Thomas Oberthür4

1University of Potsdam, Germany; 2Mineralogical State Collection Munich, Germany; 3Martin Luther University Halle-Wittenberg, Germany; 4Federal Institute for Geosciences and Natural Resources (BGR), Germany

The Merensky Reef of the Bushveld Complex, South Africa, is one of the largest resources of platinum-group elements (PGE) worldwide. Near-surface supergene ores of the Merensky Reef contain high grades of PGE and are economical ore bodies. Unfortunately, the recovery rates of these ores are low. This is the first study that investigates the variation of PGE in pristine and supergene samples of the Merensky Reef from the eastern Bushveld.

The whole-rock PGE distribution was investigated via ICP-MS and the platinum-group mineral (PGM) distribution with reflected light microscopy, SEM, and microprobe. Pristine samples reveal that the PGEs occur mainly as discrete PGMs and in solid solution in sulfides (especially Pd in pentlandite). The PGMs in the pristine ore are PGE-sulfides, e.g. cooperite-braggite or laurite; and subordinate PGE-bismuthotellurides and PGE-arsenides. During weathering, sulfur and, to a lower extent, Pd, were removed resulting in a PGE mineralogy that mainly consists of relict PGM, Pt-Fe alloys, and Pt-oxides/hydroxides. Additionally, PGEs (mainly Pd) are hosted by Fe-hydroxides and secondary hydrosilicates (e.g., chlorite or serpentine).

The highly variable distribution in the supergene ore results in very low and thus uneconomic recovery rates. The PGEs in the weathered samples occur only partly as discrete PGMs and therefore the processing is not as effective. The PGEs are also hosted by hydrosilicates and Fe-hydroxide and thus hydrometallurgical or pyrometallurgical processing of the bulk rock is necessary for the extraction of PGE, which is still uneconomic and thus new chemical bulk-leaching methods would need to be developed.



MON: 53
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Constraining the interplay of magmatic and hydrothermal processes during ore formation with numerical models

Yulia Gruzdeva, Philipp Weis

GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany

Magmatic-hydrothermal ore deposits form our largest resources of Cu, Mo, Sn and W and are formed by fluids released from magmatic intrusions into a hydrothermal system within the country rock. The potential to form world-class deposits critically depends on cross-boundary fluid fluxes at this magmatic-hydrothermal interface, which is one of the key unknowns in our current understanding of these deposits. Capturing the dynamics of these interface processes with numerical models requires to resolve mass and energy fluxes as a continuum that extends beyond the roots of hydrothermal systems and bridges the gaps between fluid flow and magma dynamics. Magma is mobile during intrusion events and can convect until it reaches a crystal lockup due to cooling and crystallization. During this process, the magma reservoir reaches fluid saturation and exsolves metal-bearing magmatic volatiles to the host rock. This magma solidification behavior depends on its chemical composition, which can be constrained by geochemical analyses of field samples. We have developed a consistent formulation for fluid generation and transport in a coupled model for viscous flow according to the Navier-Stokes Equations and porous flow with Darcy’s Law. Our simulation results suggest that the interplay of magma emplacement, magma convection and fluid release during crystallization exerts a strong control on the ore-forming potential. This contribution will present preliminary results from our coupled magmatic-hydrothermal model.



MON: 54
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Transport and reaction of light elements in pegmatitic systems at thermal disequilibrium – first insights from an experimental approach

Christian Ronny Singer, Harald Behrens, Stefan Weyer

Leibniz University Hannover, Germany

The transition from fossil towards green energy sources is one of the major challenges for our society. In order to accomplish this, large amounts of lithium are necessary as a component in Li-ion batteries. Such resources can be obtained from pegmatites. These magmatic rocks are often associated with highly fractionated granites and are therefore abundant all over the globe. Rare-element pegmatites, a sub-group of pegmatites, are often strongly enriched in Li and B and a variety of strategic elements (e.g. Ta, Nb, Be, Sb, W). There are many models for the formation of such pegmatites, however, the mechanisms leading to strong metal enrichment are yet poorly constrained.

With our experimental study we want to address, whether Li and B isotopes can be used as tracers for magmatic and hydrothermal processes in pegmatites. For this purpose, we investigate the isotope fractionation of Li and B during the interaction between a pegmatitic melt and a fluid phase in a closed system. We have developed an experimental setup, where melt and fluid coexist. Diffusive transport is directed from the pegmatitic melt through an aqueous fluid into a sink (e.g. aluminosilicate melt or muscovite). To mimic natural conditions, temperature gradients ≤ 10 K/cm along the sample can be adjusted. First results of associated diffusion couple experiments show that Li diffusion is 1) several orders of magnitude faster than B and 2) insensitive to melt composition. B diffusion, on the other hand, strongly depends on melt composition and is mainly controlled by melt viscosity.



MON: 55
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Insight into formation of hydrothermal ore deposits using a hydrothermal autoclave and X-ray absorption spectroscopy

Manuela Borchert1,2, Maria Kokh1,3, Max Wilke3, Marion Louvel4, Pilar Valsera Moreno1, Rami Al Abed3, Wolfgang Morgenroth3, Christian Schmidt5, Denis Testemale6, Edmund Welter2, Stephan Klemme1

1Westfälische Wilhelms-Universität, Münster, Germany; 2Deutsches Elektronen-Synchrotron, Hamburg, Germany; 3Universität Potsdam, Potsdam, Germany; 4ISTO, Orleans, France; 5GeoForschungsZentrum Potsdam, Potsdam, Germany; 6Institut Néel, Grenoble, France

Hydrothermal fluids play an important role during the formation of most economically explored ore deposits. While cycling through the crust these supercritical fluids efficiently dissolve and transport metals from the source rocks; metal-rich minerals precipitate on their way towards the Earth’s surface. In general, compositions of hydrothermal ore fluids are well known, e.g., by analyzing fluid inclusions in ore minerals. However, because sources and physiochemical characteristics of hydrothermal fluids vary widely, complexation and speciation of metals in the fluid and precipitation mechanisms of ore minerals are still matter of controversial debates. Conclusions on metal complexation and speciation in the fluids are usually based on analysis of quench experiments that do not consider the probably non-quenchable nature of hydrothermal metal complexes e.g., as previously reported for gold (Pokrovski et al., 2015). Thus, reliable information on metal complexation and speciation during ore deposit formation can only be obtained using in-situ data.

Here, we present an autoclave dedicated to in-situ characterization of hydrothermal fluids at high pressures and temperatures at Deutsches Elektronen-Synchrotron (Klemme et al., 2021). Besides discussing details of the experimental set-up we will also focus on results of two ongoing projects dedicated to formation of W and Sn hydrothermal ore deposits.

G. Pokrovski et al., PNAS 112 (44), 2015; Klemme et al., Rev Sci Instr, 92, 2021

Funding: Bundesministerium für Bildung und Forschung (BMBF) grant FKZ 05K16PMA, DESY Center for Molecular Water Science - Early Science Project.



MON: 56
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

On the genesis of post-subduction porphyry copper magmas

Jia Chang, Andreas Audetat

Bavarian Geoinstitute, University of Bayreuth, Bayreuth 95440, Germany

For subduction-related porphyry Cu deposits, it is generally agreed that the ore-forming magmas fractionate from mafic magmas produced by slab fluid±melt-fluxed melting of the asthenospheric mantle wedge. This model, however, is not able to explain post-subduction porphyry Cu deposits that formed after the termination of slab subduction. Popular models suggest that post-subduction porphyry Cu magmas are partial melts of former lower crustal sulfide-rich arc cumulates with or without minor contribution from potassic mafic magmas. Here we re-appraise this model via a combined approach of natural sample studies and piston-cylinder experiments. The Sanjiang region of SW China is a typical post-subduction porphyry Cu metallogenic belt that formed during the India-Asia continental collision. Based on a detailed petrographic study, we investigated whole-rock elemental and Nd-Sr-Pb isotopic compositions of variously evolved magmatic rocks and garnet-bearing xenoliths throughout the southern Sanjiang region. The results demonstrate that the continental collision-related porphyry Cu magmas formed solely by fractionation of potassic mafic magmas, and that the lower crustal partial melting model built upon wrong radiogenic isotopic compositions of the investigated garnet-bearing xenoliths. The potassic mafic magma fractionation model is further supported by crystallization experiments using a basaltic trachyandesite sample as starting material. The experimental run products reproduce not only the mineral crystallization sequence of magmatic rocks in the southern Sanjiang region but also the liquid line of descent defined by the whole-rock data. Hence, we suggest that the role of pre-existing lower crustal arc cumulates in forming post-subduction porphyry Cu magmas has been greatly overestimated.



MON: 57
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Fingerprinting fluid evolution and metal distribution in the Skouries porphyry Au-Cu deposit (NE Greece) by mineral micro-analysis

Alica Höss1, Reiner Klemd1, Manuel Keith1, Panagiotis Voudouris2, Vasilios Melfos3, Lisa Gerlach1, Karsten Haase1, Tim Baker4

1Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg, Geozentrum Nordbayern, 91054 Erlangen, Germany; 2National and Kapodistrian University of Athens, Faculty of Geology & Geoenvironment, University Campus, Zografou 15784 Athens,Greece; 3Aristotle University of Thessaloniki, Faculty of Geology, Department of Mineralogy, Petrology and Economic Geology, GR-54124, Thessaloniki, Greece; 4Eldorado Gold Corporation, 1188 Bentall 5-550 Burrard St., Vancouver, British Columbia V6C 2B5, Canada

The Skouries deposit in NE Greece is a platinum-group element enriched (⌀=149 ppb Pd, ⌀=30 ppb Pt) Au-Cu porphyry system hosted by monzonite-syenite intrusions. The porphyry stockwork consists of quartz-rich A- and B-type veins associated with potassic alteration, followed by massive sulfide-bearing veins related to chlorite-sericite alteration, and D-type veins associated with sericitic alteration. The mineralization is dominated by chalcopyrite, pyrite, bornite, and magnetite associated with native gold and Bi-Pd-rich telluride inclusions. The mineral chemistry (EPMA and LA-ICP-MS) of chalcopyrite, pyrite, magnetite, and hydrothermal quartz was used to track the physiochemical fluid evolution, and to define mechanisms enhancing metal enrichment at Skouries.

Textural differences of hydrothermal quartz generations, as reflected by distinct CL-SEM intensities, were linked to Ti-in-quartz-thermometry and quartz trace element ratios, such as Ge/Ti, Sb/Ti and Al/Ti. These ratios record temperatures around 600°C for the A-type veins, suggest a reopening of veins by a second, hotter fluid pulse (>600°C), which was followed by a decrease in temperature below 600°C for the later B-type veins. Furthermore, the sulfide mineralization is characterized by systematic variations in trace element concentrations (e.g., As, Ag, Au) and ratios (e.g., Au/Cu, Co/TI, Se/Te, As/Sb) fingerprinting physiochemical changes in the hydrothermal fluid system. Therefore, sulfide and quartz micro-analysis can help decipher small-scale processes within the porphyry system and allow to establish mechanisms controlling the metal endowment of porphyry deposits on a larger scale.



MON: 58
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

Towards coupled geodynamic and hydrothermal numerical rift models of sediment-hosted Copper and Zinc deposits

Anne Glerum1, Philipp Weis1,2, Joseph Magnall1, Sarah Gleeson1,3, Sascha Brune1,2

1GFZ German Research Centre for Geosciences, Potsdam, Germany, Germany; 2University of Potsdam, Potsdam, Germany; 3Freie Universität, Berlin, Germany

Many large sediment-hosted base metal deposits occur in failed continental rifts and the passive margins of successful rifts, e.g., in the MacArthur Basin, Australia, and the Selwyn Basin in Canada. Continental rifts and their margins provide a specific mix of elevated temperatures and heat flows, fault networks to facilitate fluid flow, sediment supply from the rift shoulders, and ocean water contributing pelagic sediments and sulfate. The large-scale geodynamics thus provide the necessary ingredients for metal leaching and deposition to occur on a variety of spatial and temporal scales. To understand the geodynamic controls on ore formation, we are therefore coupling the geodynamic code ASPECT1,2 (coupled to the landscape evolution model FastScape3,4) with the hydrothermal fluid flow code CSMP++5,6 to include realistic pressure, temperature, and heat flow conditions, as well as permeability and sediment distributions, for fluid flow and metal leaching/deposition. This coupled workflow crosses temporal scales of millions of years to years and spatial scales of hundreds of kilometers to meters. We present preliminary results from geodynamic modelling of large-scale continental rifting and hydrothermal simulations at specific snapshots of the upper 10 km of crust of this large-scale geodynamic evolution, showing the effect of rift duration, adjacent craton thickness, and erosion efficiency on sediment-hosted Cu and Zn deposits.

1Kronbichler et al. (2012). GJI191(1), 12–29.

2Heister et al. (2017). GJI, 210(2), 833–851.

3Neuharth et al. (2022). Geology, 50(3), 361–365.

4Braun & Willett (2013). Geomorphology, 180-181, 170-179.

5Weis et al. (2014). Geofluids, 14(3), 347–371.

6Rodríguez et al. (2021). GCubed, 22(6).



MON: 59
Topics: 9.1 Dynamics of ore-forming processes: constraining mechanisms of metal enrichment

The behaviour of Sn and W at the magmatic-hydrothermal transition: Insights from natural and synthetic fluid inclusions

Julie, Anne-Sophie Michaud, François Holtz, Ingo Horn

Institute of Mineralogy, Leibniz University, Hannover, Germany

Tin (Sn) and tungsten (W) have been established as strategic metals, whose resources are mainly related to highly evolved, volatile-rich granitic systems and related hydrothermal fluids. Their transport and enrichment results from a combination of melt- and fluid-driven processes. To evaluate the relative importance of these processes, we propose to combine the study of natural and synthetic fluid inclusions (FIs). Natural FIs occurring in early (associated with cassiterite) to late hydrothermal (associated with wolframite) quartz of the Argemela magmatic-hydrothermal system (Central Portugal) are mainly of aqueous (average XH2O = 0.94±0.04) L+V±S type. Raman spectrometry revealed an evolution from V-rich CO2-CH4-N2 to L-rich CO2±N2-CH4 inclusions through the transition and graphite is present in several early inclusions, suggesting relatively reduced conditions and a potential inheritance from the source. In addition, and because further work is needed to understand the fluid/melt partitioning of Sn and W, several experiments were conducted at 700 and 800°C, 200MPa and variable fO2 and salinities to synthetize FIs. A synthetic glass was produced to mimic the major element composition of the Argemela highly peraluminous intrusion and concentrations of W, Sn, P and Li were varied. Inclusion-free quartz were used to trap the fluids. First results prove the feasibility of the study. Microthermometry and LA-ICP-MS analyses are in progress for both natural and synthetic FIs.



Application for Ramdohr Award in Poster session on Monday
MON: 60
Topics: 9.2 Energy and technology critical raw materials: from genesis to processing

Microstructural investigations of the interaction between embedded fuel particles and Portland cement clinker

Charlotte Linden1, Matthias Böhm2, Thorsten Geisler1, Aneta Knöpfelmacher2, Nils Bodendiek2

1Rheinische Friedrich-Wilhelms-Universität Bonn; 2Verein Deutscher Zementwerke e.V.

In view of current climate and energy policies, the cement industry is striving to save emissions and is increasingly using alternative fuels (AF) for the clinker burning process. AF are generally more coarse-grained and have a higher probability to fall incompletely burned onto the clinker bed, where they become embedded and can lead to changes in the material by locally causing reducing conditions. However, the qualitative and quantitative understanding of relationships between fuel particle sizes and the resulting material properties of the clinker is still limited. Here, we show experimentally that local reducing conditions can indeed lead to the reduction of iron and thus to local changes of the phase assemblage. The altered oxygen partial pressure within the pore volume of the sample also causes a brown coloration of the clinker. The extent of the changes was found to depend on the fuel particle size and the residence time of the embedded fuel particles in the clinker bed in the kiln. The new qualitative and quantitative data enable the optimization of the clinker burning process, which in turn can lead to an increasing use of AF in the future.



MON: 61
Topics: 9.2 Energy and technology critical raw materials: from genesis to processing

Sm-Nd dating of fluorites from the Vergenoeg, Buffalo and Morgenzon 533 KQ deposits, Bushveld Igneous Complex, South Africa: Evidence for late hydrothermal fluorite formation

Guillaume Jacques1, Torsten Graupner1, Reiner Klemd2, Friedhelm Henjes-Kunst1

1Bundesanstalt für Geowissenschaften und Rohstoffe (BGR); 2GeoZentrum Nordbayern, Friedrich-Alexander-Universität (FAU) Erlangen-Nürnberg

We investigated three fluorite deposits associated with the Bushveld Igneous Complex in South Africa for their trace element characteristics (e.g., REE+Th+U): the two major and world-class Vergenoeg and Buffalo deposits, as well as the small Morgenzon deposit. Combined with published and unpublished data from the Vergenoeg deposit (host rock and mineral separates), which yield an age of 2050 ± 17 Ma (MSWD = 0.65), the new host rock and fluorite Sm-Nd isotope data confirms a primary magmatic origin for the Buffalo deposit as well. Whereas the host rock data for Morgenzon plot close to the 2050 Ma isochron, the Morgenzon fluorite data significantly diverge and plot along an errorchron corresponding to an age of 318 ± 59 Ma (MSWD = 7.4). The Morgenzon fluorites are also depleted in the abundances of REE+Th+U by almost a factor 100 compared to the Buffalo fluorites. Cathodoluminescence (CL) imaging reveals complex zoning patterns with a wide range in bluish CL colours for the Morgenzon fluorite. In contrast, fluorite from Buffalo is always very homogeneous (pale bluish CL colour), which indicates a single stage and likely primary magmatic formation process for the latter. Combined trace element and isotope data and CL evidence for the Morgenzon deposit suggest a late hydrothermal fluorite formation unrelated to the Bushveld igneous event.



MON: 62
Topics: 9.2 Energy and technology critical raw materials: from genesis to processing

Transtensional fault segments and fluid migration in the Upper Rhine Graben

Felix Allgaier, Benjamin Busch, Christoph Hilgers

Structural Geology & Tectonics, Institute of Applied Geosciences, Karlsruhe Institute of Technology (KIT)

The Upper Rhine Graben is utilized for geothermal- and hydrocarbon exploration, and considered for lithium mining from brines. Subsurface exploration requires an understanding of reservoir- and fault properties, the geomechanical response of faults, and associated fluid migration. Slip- and dilation tendency analysis is conducted to identify fault segments in the stratigraphy, which might potentially act as fluid migration pathways.

Fluid migration is reflected by upward hydrocarbon migration of different oil types sourced from the Posidonia shales along fault zones and locally from the Lower Pechelbronn Beds (eg. Bruss 2000). For example, the reservoir quality of the previously explored and hydrocarbon producing Cenozoic Meletta beds is highly variable, decreasing with depth, ranging from 4.5 to 26.3% porosity and 0.09 to 150 mD permeability at ambient conditions (Bruss 2000, Sauer 1981, Schad 1964).

Published stress field and structural data indicated the considered N-S trending fault section of the generally NNE-SSW oriented Leopoldshafen fault 7 km north of Karlsruhe to have a transtensional character enabeling fluid migration. High slip and moderate dilation tendencies indicate this fault segment to be favourably oriented within the present-day stress field to slip or creep, depending on rock strength and SGR fault properties.



MON: 63
Topics: 9.2 Energy and technology critical raw materials: from genesis to processing

Considering the potential chromite resources of Mirdita (Albania), Troodos (Cyprus) and Muğla (Turkey) ophiolites

Sima Akrami, M. Junge, F. Brandmiller, M. Kaliwoda, W.W. Schmahl

LMU, Germany

Chromitites are economically relevant sources for chromium, and platinum-group elements (PGE). Since chromium is resistant to corrosion and abrasion, it is a vital item in stainless (74%), alloy steel markets (19%) and refractory materials. The PGE are used in catalytic converters, auto-catalysts, chemical manufacture, electrical products, petroleum refining, and jewelry.
The European Commission published the global chromite production in 2020, which amounts to 40 million tons. Currently, the primary chromite production stems from South Africa (46%), followed by Kazakhstan (16%), Turkey (11%), and India (10%). Albania (2%) is the third-largest producer of chromite in Europe after Turkey (11%) and Finland (4%). Although Cyprus has chromite resources, there is currently no economic mining activity in this country. However, Cyprus could be an additional important supplier since it belongs to the European Union and can thus advance as an essential production country for the European Union. Due to the limiting countries mining chromite and the limitation in the refining step, there is a risk that the chromium supply could lead to bottlenecks.
After studying the chromitites of three different places: Mirdita (Albania), Troodos (Cyprus) and Muğla (Turkey) ophiolites from point of Scanning Electron Microscope (SEM), Electron Prob Microanalyzer (EPM). Our preliminary data shows that the chromitites of the different deposits show similarities. However, our data sets also shows that the chromium concentrations in Cyprus are lower compared to the samples from Turkey and Albania. Further research on these samples sets is needed. Therefore, we will conduct Raman spectroscopy and carry out further geochemical and petrological studies to understand the genesis of the chromite deposits.



MON: 64
Topics: 9.4 Chemical sediments and mineral deposits in basins: archives of paleoclimatic, hydrogenetic, biogenic, hydrothermal, and diagenetic, processes throughout Earth’s history

Revised lithostratigraphy of the Paleoproterozoic Porkonen banded iron formation and associated sulphidic shales, Northern Finland

Grigorios Aarne Sakellaris

Aristotle University of Thessaloniki, Greece

The Palaeoproterozoic (~2.0 Ga) Porkonen Formation in the Kittilä greenstone belt (or terrane) in northern Finland is an exceptionally well-preserved succession of banded iron formation, shale-dominated units and submarine lava. The Formation comprises six distinct lithological units that from the base upwards include: a. massive chert b. banded magnetite±siderite-chert (iron ore) c. (Mn)siderite±chlorite-chert d. iron sulphide-rich black shale and breccia (3) tuffaceous shale and tuff and, (4) andesite/rhyolite.

The iron ore has a thickness of approx. 8 meters, laterally discontinuous (<12 km) and an average Fe content of 30.5%. The overlying manganese-rich siderite horizon (3-5m) has an average of 2% Mn, whereas the following 7m thick, sulphide-rich black shale averages at 27% Fe showing a maximum content of 47.9% Fe in one-meter interval. The latter shows elevated contents in Zn, Cu, Ni, Ag, Cd and Au.

All lithological units consist of low-grade metamorphic mineral assemblages, exhibiting primary sedimentary and early diagenetic features, and have contacts typically conformable and gradating.

Single-grain layering of micron-sized magnetite alternating with micritic carbonate, apatite and chert characterize the iron-oxide bands whereas primary colloidal textures, abundant contractional fractures, graphite-stylolites and crackle microbreccia characterize the chert bands. In the shale-dominated units the rhythmic, planar-parallel lamination of authigenic carbonates, diagenetic pyrite, and chert and pyrite nodules, have been contorted by penecontamporenous soft-sediment deformation manifested by slump structures, load casts, and intraformational breccia with angular graphite fragments in a massive iron-sulphide matrix.

The lithostratigraphy may predict a layered -in oxygen ocean with hydrothermally-dominated Fe-Mn-rich deep water mass.



MON: 65
Topics: 9.4 Chemical sediments and mineral deposits in basins: archives of paleoclimatic, hydrogenetic, biogenic, hydrothermal, and diagenetic, processes throughout Earth’s history

The Shahejie Formation in the Dongpu Depression, Bohai Bay Basin, China: Geochemical investigation of the origin, deposition and preservation of organic matter in a saline lacustrine environment during the Middle Eocene

Tianyu Zheng, Laura Zieger, Alireza Baniasad, Sebastian Grohmann, Ralf Littke

RWTH AACHEN UNIVERSITY, Germany

A new set of geochemical, petrographical and mineralogical data on important petroleum source rocks from Eocene Shahejie Formation in the Bohai Bay Basin, Eastern China is presented to investigate organic matter precursor material, thermal maturity and paleoenvironment during deposition of the Es3U, Es3L, Es3M and Es4U members. Different maturity parameters determine early mature to peak oil mature stages and maturity increase with burial depth. Alginite is the predominant maceral, whereas vitrinite and inertinite are rare. Studied shales and marlstones were deposited under episodic PZA as revealed by aryl isoprenoids. Bottom water conditions were anoxic most of the time except for Es3M. A fairly uniform biomarker composition displayed in Es4U indicates relatively stable hypersaline lake conditions with a shallow chemocline based on the high Gammacerane Index ˃0.6 and abundant aryl isoprenoids. Salinity changed during deposition of Es3L according to variable C24 Tet-related parameters and evaporite minerals content. The aquatic algal organisms, i.e. haptophyte algae, diatoms and bryophytes which are reflected by abundant nC3739 alkanes, a variable sterane pattern, and other biomarkers, were flourishing during Es3L. Small concentration of specific PAHs, i.e. retene, cadalene, fluoranthene, indeno[1,2,3-cd]pyrene and benzo[ghi]perylene in Es3L, may be attributed to limited terrigenous input. Es3M was deposited in a normal lacustrine environment under rather low salinity conditions with substantial input of organic matter derived from algae. During Es3U, saline lake conditions were re-established accompanied by algal and microbial input, especially cyanobacteria as deduced from MMAs and 2α-MeHs, methanogens from abnormally abundant phytane, PMI, squalane, and methanotrophs from 3β-MeHs.



MON: 66
Topics: 11.1 Shaping the future of geoscientific data: The path to FAIR data

The TRR170-DB Data Repository: Improving Metadata for FAIR Planetary Replication Datasets

Elfrun Lehmann, Harry Becker

Freie Universität Berlin, Germany

TRR170-DB (https://planetary-data-portal.org/) is a re3data (r3data.org) referenced data repository that stores machine-readable replication datasets of the collaborative research center ‘Late Accretion onto Terrestrial Planets’ (TRR 170) and from other institutions in the planetary science community. The TRR170-DB framework aligns their data storage with the FAIR (Wilkinson et al., 2016) data life cycle as promoted by the German National Research Data Infrastructure Initiative (www.nfdi.de) and various national and international funding agencies and initiatives. The TRR170-DB repository will be permanently hosted by Freie Universität Berlin, which ensures long-term preservation of, and access to TRR170-DB’s published data.

TRR170-DB has a flexible data-driven metadata system that uses tailored metadata blocks for specific data communities. Metadata and files of a published replication dataset can be exported in various open international metadata standards and file formats. This ensures that all published data are generally accessible for other external databases and repositories (“interoperability”).

A major requirement for the reuse of data is metadata information that reflects up-to-date analytical developments. Currently, we are expanding metadata templates to incorporate additional standardized information on samples and materials, analytical methods and additional experimental data in the area of geochemistry. This ongoing process will involve international scientific communities and initiatives (OneGeochemistry, Astromaterials Data System, NFDI, etc.) by discussing and testing joint standards and practice. Our efforts on advancing metadata for geochemical analysis data parallel with establishing an interest group on ’metadata standards for instrumental analysis data in geochemistry’ in the context of the German NFDI4Earth, a consortium of the NFDI Initiative.



MON: 67
Topics: 11.3 Young Scientist Session

The Distribution of Geogenic and Anthropogenic Rare Earth Elements and Yttrium in Major European Rivers: The PANORAMA River Monitoring

Addis Kokeb Alemu1,2, Keran Zhang1, Franziska Klimpel1, Anna-Lena Zocher1, Michael Bau1

1Jacobs University Bremen, Germany; 2University of Gondar, Ethiopia

Rare earth elements and yttrium (REY) are vital components in numerous high-technology products and processes. Consequently, they are continuously released into the environment from various point and diffuse sources and have become emerging micro-contaminants in natural waters. The presence of anthropogenic Gd due to the release of Gd-based MRI contrast agents via the effluents from waste water treatment plants is well-documented from all continents except Antarctica. Contamination with anthropogenic La has been reported for the lower reaches of the Rhine River in Germany. However, in spite of these observations of anthropogenic REY in the environment, a systematic overview on the distribution of all naturally occurring geogenic and anthropogenic REY in major European rivers and lakes is still lacking. To fill this gap, waters and organisms (with a focus on mussels) from rivers and lakes in the European Union are studied as part of the EU-ITN “PANORAMA”.

We will report first results from recent sampling campaigns, including samples from the Danube River and its major tributaries between its headwaters in southwestern Germany and just downstream of Belgrade, Serbia, from the Seine River in the vicinity of Paris, France, and for major rivers of the Iberian Peninsula in Portugal and southern Spain. These will be compared to data for rivers in the North German Basin (Ems, Weser, Elbe, Havel), the Rhine River and its tributaries between Lake Constance and the German-Dutch border, and several major rivers on the Fennoscandian Shield in Sweden and Norway.



MON: 68
Topics: 11.3 Young Scientist Session

Maturation and migration processes in intact source rock micro plugs induced by chemical and thermal treatment: A new approach combining Rock-Eval pyrolysis and organic petrography

Arysthasya Arysanto1, Ralf Littke1, Markus Dörner2, Michael Erdmann2, Sebastian Grohmann1

1RWTH Aachen, Germany; 2Equinor ASA, Bergen, Norway

This study proposes a new approach to investigate hydrocarbon generation and migration processes in petroleum source rocks under laboratory conditions. For the first time, programmed open-system pyrolysis using a Rock-Eval 6 instrument is applied on small, polished source rock plugs to induce changes in the type and distribution of solid bitumen, which is qualitatively investigated by means of organic petrography before and after treatments. This approach allows us to directly visualize the evidence of solid bitumen (SB) formation and distribution after the following treatments: (1) thermal extraction (300°C for 3 min), (2) chemical extraction of the surface using dichloromethane (DCM), and (3) artificial maturation up to 400 to 500°C. After each step, the surface of micro plugs was digitally scanned to allow a comparison of specific areas of interest before and after the treatments.

After thermal extraction, the volume of observed SB in the early- and moderately mature samples slightly increased, while most of the thermally mobilized bitumen from inside the plug was evaporated. The initial solid bitumen was not or hardly affected by thermal extraction at 300°C for 3 min, i.e. it was thermally stable at this temperature. After DCM treatment, SB in the early mature samples was almost completely dissolved. While some SB was dissolved in the moderately mature sample showing more mature and stable SB. After the artificial maturation, the volume of SB in early- as well as in moderately mature samples increased, indicating the presence of new SB due to bitumen migration from the plug.



MON: 69
Topics: 11.3 Young Scientist Session

“Heat In Place” assessments for Berlin/Brandenburg’s deep geothermal potential

Laureen Benoit1, Judith Bott2, Magdalena Scheck-Wenderoth1,2

1RWTH Aachen University, Germany; 2GFZ - German Research Centre for Geosciences, Potsdam, Germany

Geologically located in the Northeast German Basin, Berlin and most parts of Brandenburg are known to be potentially suitable for deep geothermal energy usage. This source of energy is not yet well-established in the area. However, regarding Germany’s transition towards climate-friendly and regional energy solutions, the energy demand from renewables is rapidly increasing. Thus, geothermal exploration and assessing geothermal potential is significant. We assess “Heat In Place” (HIP) as quintessential part of the geothermal potential for a series of litho-stratigraphic units for Berlin and Brandenburg.

Geothermal potential is defined as considering characteristics of a specific geothermal plant and/or the geological reservoir. We concentrate on the latter geological aspects and take a 3D geological and two different 3D thermal models of Brandenburg as basis for the HIP calculations. This HIP approach corresponds to a volumetric quantification of contained energy within 16 litho-stratigraphic units, each taking variable thickness, mean temperature, porosity, density, and specific heat capacity into account. This results in a series of new geothermal potential maps derived from different thermal models: Firstly, conductive heat transport, and secondly, coupled thermal-hydraulic simulations. We aim at deepening the understanding of HIP maps for geothermal power plant site decision making by showing how the calculated heat varies between those two modelling approaches, and different parameter estimates.



MON: 70
Topics: 11.3 Young Scientist Session

Neogene-Quaternary evolution of the La Baja Guajira Basin, Colombia: burial and thermal history with implications on petroleum systems

Leidy Castro-Vera1,2, Ralf Littke1, Stefan Back1, Rocío Bernal-Olaya3

1RWTH Aachen University, Germany; 2Grupo de investigación en Ciencias de la Tierra y Energía, Amonite SAS, Colombia; 3Universidad Industrial de Santander, Colombia

The La Baja Guajira Basin is the primary gas-producing region of Colombia. This study analyses regional 2D-seismic reflection and borehole data to better understand the Neogene-Quaternary events controlling the basin.

The basement’s configuration controlled the sedimentation, and its structural depressions formed the main depocenter (Tayrona Sub-basin). The basement is a pre-rift sequence that displays an abrupt westward deepening of its top from 0.8 km to 12 km depth over 30 km.

Two phases of rifting occurred during the Early Miocene: 1) half-graben formation along onshore and proximal offshore areas, and 2) extension migrated westward and formed the necking domain along the distal offshore area.

From the latest Early Miocene to the Early Pliocene, subduction of the Caribbean Plate underneath South American Plate influenced the basin’s offshore area by compressional deformation associated with inverted reactivation of larger normal basement-rooted faults.

During the Middle Miocene, the extension had ceased, sediments filled significant residual accommodation space, and the proximal area remained quieter favouring the deposition of clinoforms that prograded westward until the Quaternary.

Two exhumation pulses (Middle Miocene and Early Pliocene) of adjacent areas resulted in increased subsidence and sedimentation rates, which led the rocks to reach maximum temperature peaks and burial depths. In the Late Miocene, a period of erosion affected the northern proximal areas.

From Late Pliocene to Pleistocene, sea-level changes dominated over tectonism. Ongoing hydrocarbon generation can be expected in the south. High sedimentation rates calculated can lead to microbial gas generation and favour the preservation of biogenic gas accumulations.



MON: 72
Topics: 11.5 Open Session - Geology

Shards of glass: incorporation of trash in modern beachrock on Eleuthera Island, Bahamas, and its implications for in situ studies of fast carbonate cementation

Michaela Falkenroth1, Scarlette Hsia2

1RWTH, Aachen, Germany; 2University of Texas, USA

Beachrocks are bodies of beach sediment cemented with carbonate minerals. They are not only useful archives of coastal evolution, but are also investigated as means of protection from coastal erosion. Beachrock formation is known to permanently alter the morphodynamics of a coastline and lock sediment in place, while reflecting wave energy. The cementation occurs on a scale of years rather than millennia, but observations of very young beachrocks with well constrained ages are still rare. Furthermore, our understanding of the cementation process is limited, although crucial to the creation of artificial beachrocks for engineering purposes.

On the Bahamian island Eleuthera modern beachrocks have incorporated high amounts of trash such as glass, rubber and microplastics. While the inclusion of anthropogenic materials into the rock record raises questions on limestone nomenclature, it also provides chances for the study of beachrocks. The glass is of particular interest as it shows no signs of rounding, indicating very recent cementation. This facilitates an in situ observation of the cementation process over an extended period of time, uncovering possible links to environmental parameters like temperature, availability of freshwater, inundation and weather phenomena like storms. To unravel the structure of the microbial communities involved in cementation a combination of petrography, SEM and environmental DNA can be used on the cements.



MON: 73
Topics: 4.5 Tectonic Systems (TSK Open Session)

Structural and geochemical data of the Mourne nappe near Kerames (Crete): Constraints on the tectonometamorphic evolution of the Uppermost Unit

Nicolas Neuwirth1, Nora Groschopf2, Jolien Linckens1, Horst Marschall1,3, Rainer Petschick1, Gernold Zulauf1

1Institut für Geowissenschaften, Goethe-Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany; 2Institut für Geowissenschaften, Johannes-Gutenberg-Universität, Johann Joachim Becher-Weg 21 55128 Mainz, Germany; 3Frankfurt Isotope & Element Research Center (FIERCE) at Goethe Universität Frankfurt, Altenhöferallee 1, 60438 Frankfurt am Main, Germany

The Uppermost Unit of Crete is attributed to the Internal Hellenides and consists of different nappes derived from an Upper Cretaceous arc (Asterrousia), and a late Jurassic to Cretaceous subduction-accretion complex (Vatos, Arvi, Miamoux).

Blueschists of the subduction-accretion complex of central Crete (Preveli nappe, T = ca. 350°C, P= ca. 1.2 GPa) are resting on top of Pindos rocks and are overlain by Cretaceous Vatos flysch, Jurassic ophiolites and a second sequence of blueschist-facies rocks referred to as Mourne nappe.

The Mourne blueschists show a large variety of amphiboles, such as glaucophane, riebeckite, richterite, ferri-winchite, barroisite, magnesio-hornblende, edenite and actinolite. K-Ar dating of barroisite and phengite yielded late Jurassic ages (Seidel et al., 1977).

Top-to-the SW shearing under epidote blueschist-facies conditions led to the dominant foliation of the Mourne metabasites, which is characterized by the shape-preferred orientation of blue amphibole, omphacite (as relics), epidote, rutile and titanite.

Growth of barroisite, magnesio-hornblende and epidote indicate isothermal decompression under epidote-amphibolite facies conditions.

Cooling and further decompression is indicated by several generations of younger veins mineralized with albite, quartz, epidote, actinolite (greenschist facies) and actinolite, epidote, prehnite, calcite (prehnite-actinolite facies).

The youngest deformation led to discrete foliation-parallel shear zones under brittle conditions, related to the emplacement of the Mourne nappe on top of the ophiolites.

Funding by DFG (Zu 73-34) is gratefully acknowledged.

References

Seidel E et al (1977) Metamorphic rocks of late Jurassic age as components of the ophiolitic mélange on Gavdos and Crete (Greece). Geol. Jb. 28:3–21



 
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