The presentation provides an overview of BGR's deep-sea mineral resource exploration and informs on recent developments in deep-sea mining. Metals such as copper, nickel and cobalt play a vital role in the production of regenerative energies and high-tech electronic products. Currently, these metals are solely extracted from land sources, but increasing global demand has spurred interest in deep-sea deposits located in areas beyond national jurisdiction. Polymetallic nodules, cobalt-rich manganese crusts and massive sulphides found at water depths of 1 to 5 kilometers are seen as potential sources of such raw materials. Germany, as an industrial country with high raw material demands, heavily relies on metal imports. As a potential measure to reduce dependence and secure supply, Germany has invested actively in the exploration of marine mineral deposits and their environment in the eastern Pacific and southwestern Indian Ocean during the last two decades. The International Seabed Authority (ISA) is currently negotiating regulations for the mining of these resources (“Mining Code”). At the moment, the focus is on adopting regulations for polymetallic nodule mining, possibly by 2024. However, companies could potentially already submit mining applications today, to be considered by the Council despite the absence of a full set of binding regulations. Significant progress has recently been made in overcoming the technical challenges of mining the deep sea. Several contractors have successfully tested mining systems and are currently monitoring the resultant impacts on the environment and the biodiversity.

Two zoned inactive chimney samples from the SMAR 26°S (Xunmei) hydrothermal field were studied petrographically and by in-situ LA-ICP-MS analysis. Morphologically different pyrites precipitated with increasing temperatures from the outermost chimney wall to intermediate zone, then to the inner zone, and finally to interstice pore fillings which represents the late mature stage. The distribution of trace elements in pyrites across the chimney indicates a strong dependence on time, temperature, and associated sulfide minerals. The variation of trace elements in different paragenetic stages of pyrite reveals that the hydrothermal system most likely evolved from low-temperature low-chloride liquid-dominated fluids (enriched in Zn, Cd, Tl, Ag, Pb, Mn, Mo, and V) to higher temperature, vapor-dominated fluids (Cu, Au, Te, and Bi), probably representing magmatic volatiles, and then to high-temperature fluids (Co and Se). In the waning stage of the hydrothermal system, circulating hot fluids in auxiliary conduits were depleted in most trace elements. LA-ICP-MS time-depth profiles reveal that Co, Se, and Mo are present mainly in lattice substitution, whereas Cu, Zn, Cd, Tl, Ag, Te, and Bi are related to micro-/nano-inclusions. Profiles for As, Pb, Au, and Sb can be either smooth or irregular, indicating both lattice substitutions and inclusions. Adsorbed films on pyrites control the distribution of V and Mo. To conclude, the behavior of trace elements is strongly associated with the fluid evolution during chimney growth, where trapping of micro-/nano-inclusions and surface adsorption are seen more frequently at the low-temperature stage, whereas lattice substitutions are dominant at elevated temperature stages.

Analytical challenges such as low concentrations and a saline matrix, contamination risks during sampling and analysis, and the accessibility of remote ocean areas limit available methodologies for the investigation of trace elements in the open ocean and call for innovative, easy to use and robust investigation tools. Furthermore, the application of methodologies for the monitoring of e.g., deep-sea mining activities as part of environmental impact assessments will become of increasing importance for future marine research. We here evaluate an in situ passive sampling method using the technique of diffusive gradients in thin films (DGT), focussing on Mn, Cu, Ni, V, Cd, As, Sb, and rare earth elements and yttrium. Sampling was performed in bottom seawater above the BGR contract area for polymetallic nodule exploration in the Clarion Clipperton Zone in the NE Pacific. We present data from different passive sampling setups at depths between 0.3 m and 550 m above the seafloor accumulating trace metals for periods of 3 days up to 2 years, and discuss the effects of deployment time and the binding membrane type. Derived concentrations represent the labile fraction of the metals and hence that fraction that is (bio)available for an uptake through cell membranes. Results are compared to point sampling of seawater providing trace metal concentrations for different size fractions, which allows to constrain the degree of lability of dissolved trace metals. We further present results from the monitoring of a collector mining test of polymetallic nodules with respect to trace metal mobilization at the seafloor.

Methane (CH₄) is an important greenhouse gas, but our understanding of the magnitude of its sources is fraught with considerable uncertainties. Quite neglected in early atmospheric methane budget studies, Earth’s degassing is today considered a major natural source of methane. Geological (natural fossil) methane emissions, including gas seepage in petroliferous sedimentary basins (macro-seeps, microseepage, marine seepage) and geothermal exhalations, were estimated at the global scale by several research groups, based on bottom-up and top-down procedures, and accounting for ~40-50 Tg CH₄ yr^-1 (latest review and discussions on conflicting estimates are in Etiope and Schwietzke, 2019, and Thornton et al. 2021). This value is equivalent to roughly one-third of the average emission attributed to wetlands, and it rivals with the high uncertainty of freshwater sources. Global gridded mapping was developed to provide the spatial distribution of the geological methane sources, as well as their isotopic (¹³C/¹²C) composition and potential intensity (Etiope et al. 2019), and it has been used to refine fossil fuel industry and microbial CH₄ emission budget. Geological emission breakdown at continental scale could be derived (e.g., Petrescu et al. 2023), with the emission values that must be considered only in terms of “order of magnitude”. The geo-CH₄ sources are now included in the methane budget of the Global Carbon Project (Saunois et al. 2020), where they are compared to other natural and anthropogenic sources, including an analysis of double-counting with some biological sources. Correct definitions, source attribution, uncertainties and limits define the roadmap strategy for refining emission estimates.

In spite of the decreasing production, Romania remains one of the most important oil and gas producers in Europe. The European inventories of anthropogenic methane release reveals unexpectedly high emissions related to the oil and gas industry in Romania. The number of drilled wells in Romania is exceeding 60,000, with the majority of them currently being inactive. A first approach to quantify the methane emissions from active wells was conducted within the ROMEO project. The highest emissions were observed at the facilities with poor technical maintenance. As part of the UNEP-funded project Global Analysis of Methane Emissions from Abandoned Oil and Gas Wells, an evaluation of methane release from inactive wells is ongoing. No comprehensive inventory of the inactive wells is available for the moment at a national level. The ENVERUS (DrillingInfo), database provides information on 6348 wells in Romania, out of which 776 wells in the Transylvanian Basin. More than 72% of the reported wells were dry, while different amounts of oil and/or gas have been found in the others. According to the nationally applicable closure procedure, most of the wells are plugged and buried, making their identification and detection of gas leaks difficult. In a few cases, substantial methane emissions have been reported, which may pose a threat to neighboring residents.

Acknowledgment: this contribution was supported by the project Global Analysis of Methane Emissions from Abandoned Oil and Gas Wells, funded by UNEP.

All hydrocarbon reservoirs leak slightly. At sites with only minor leakage the hydrocarbons (HC) infiltrating the sediment from below are completely metabolized before reaching the sediments surface due to microbial activity, thus not creating any surface manifestations, e.g. seeps. Nevertheless, the HC influx will change geochemistry as well as microbial community composition and activity in the affected area because electron donors are added into the system. The PROSPECTOMIS project wants to detect these changes to develop a minimally invasive and low-cost tool do detect HC reservoirs using omics and geochemistry techniques.

In November 2021 we recovered fifty 2-3 m long sediment cores from three minor HC seepage zones and two non-seepage reference zones in the southern Barents Sea and sampled sediment and pore water with high spatial resolution.

While Fourier-transform ion cyclotron resonance mass spectrometry and cell abundances did not show any differences between HC seepage zones and reference zones, multiple pore water concentration profiles e.g. for Manganese, Calcium, Silicon, Strontium, Sulfide revealed differences. Also, higher fluxes of sulfate and alkalinity in HC zones indicate that the sink for sulfate and the source of alkalinity must be shallower in HC zones, most probably caused by anaerobic oxidation of methane (AOM) below the sampled depth interval. Linear sulfate pore water profiles indicate no net turnover of sulfate. Nevertheless, we observed low rates of sulfate reduction using radiotracer incubations, mostly in HC zones.

Combining these parameters with multi-omics datasets will reveal potential indicators for minimal HC seepage.

The crystalline basement below the giant Norwegian Troll field has been subject to research and publication for many decades. Still no well bore has penetrated the deep crystalline basement. An ever-increasing amount of geophysical information, documents pronounced basement heterogeneity. The seismic reflection patterns suggest the presence of mappable fluid reservoirs within metamorphic basement rocks.

High-reflection-low-density geobodies appear to be connected to major detachment zones with varying seismicity, but avoiding younger transform lineaments. The features are considered to have formed during the collapse of the Caledonian mountains, opening the precursor basins of the North Sea and the Northern Atlantic Ocean. The structures are partly inherited from contractional features, formed during the Caledonian continental collision between Baltic and North American plates. Former and present-day fluid migration, using this inherited deformation pattern, is significant for understanding the development of one of the most important energy sources for Europe.

While earlier speculations about origin and significance of the strong seismic reflections had to be based on presumed analogues on the Norwegian mainland, we will present evidence from new, high quality seismic, gravity, magnetic and magneto-telluric data and propose new working hypotheses for their geologic origin. Pointing to low density, low magnetism and low resistivity, our mapped „geo-bodies“, could form fluid reservoirs that have influenced the regional development of the Greater Troll area.

The continental subsurface contains approximately 12 – 20% of Earth’s biomass. In deep rock environments this biomass dwells in aqueous spaces, fractures and pores of the rock, either attached in biofilms or free-living in the fluids. Meta-analyses have suggested a core deep biosphere microbiome from pre-collected data but face issues such as difference in sampling procedures, DNA extraction methods, negative control protocols, sequencing primers etc., which may introduce false variation. Addressing this issue and striving for consistent methodology, 7 sites of the Finnish Fennoscandian Shield was studied between 2009 – 2021 ranging in depth from 100 to 2300 m. Some of the sites have deep groundwater with more than 50 Ma residence times, whereas in other places the groundwater is considerably younger. All microbiomes contained bacteria, archaea and fungi, and the microbial community composition differed greatly between sites indicating that rock type and hydrogeochemistry play a great role in moulding the communities. Chemoheterotrophy was the universally dominant predicted metabolic strategy. The bacterial numbers in the groundwater were between < 1 to more than 5 x 10⁶ 16S rRNA gene copies mL^-1 but did not necessarily reflect sampling depth, but rather the concentration of DOC and DIC. In addition, dormant microbial communities activated within hours after introduction of CO₂ or methane. Finally, groundwater monitored at one site for 10 years showed that the microbial communities did dot remain static but varied in size (up to 100-fold) and composition over time in a cyclic manner, interchanging between mainly two distinct community compositions.

Nano-magnetite is a potential archive for biosignatures of iron-cycling microorganisms in hydrothermal systems, which are widely considered to be among the most ancient microbial habitats on Earth. Sulfidic diagenesis driven by hydrothermal fluids and microbial sulfur cycling potentially causes the rapid transformation of magnetite to iron sulfide minerals. Thus, identifying nano-magnetite and its transformation products in hydrothermal sulfide deposits is crucial for reconstructing iron- and sulfur-cycling microbial life in deep time. However, the identity and characteristics of iron sulfide minerals resulting from nano-magnetite sulfidation at hydrothermal conditions have previously not been constrained. Here we present experimental data on sulfidation reactions of synthetic and biogenic nano-magnetite at physical and chemical conditions relevant to microbial habitats in hydrothermal systems on early Earth (<121°C, anoxic, sulfidic). We characterize the resulting precipitates with analytical imaging techniques, mineralogical methods, and geochemical approaches (e.g., SEM-EDS, µXRD, Raman spectroscopy, sequential Fe extraction). Our results demonstrate a potential taphonomic bias against nano-magnetite in sulfidic hydrothermal habitats and suggest that biosignature records of iron- and sulfur-cycling microorganisms in ancient hydrothermal sulfides are affected by diagenetic fluid-mineral interactions.

Lake Towuti, Indonesia is a stratified ferruginous (iron-rich, sulfate-poor) system whose deep basin experienced dynamic changes in trophic and redox conditions since the Middle Pleistocene. As wet and dry periods alternated and sediment accumulated, microbial life sustained by metals and organic substrates became entombed in the subsurface. A 1 Ma stratigraphic archive retrieved by the International Continental scientific Drilling Program (ICDP) was sampled aseptically on site for microbiology analysis. Through taxonomic and functional analyses (16S rRNA amplicons, metagenomics), the BioMetArchive project aims at the first comprehensive characterization of the lacustrine subsurface biosphere in terms of diversity, abundance and metabolic functions.

Metagenomic data combined with high resolution cell counts and pore water geochemistry allowed to characterize the distribution of microorganisms throughout the core and to identify which microbial taxa and metabolic features are involved in the major biogeochemical cycles and organic matter remineralization during sediment burial. Results show a drastic decrease in the cell counts (from 10⁹ to 10⁴) as electron acceptors in the pore water chemistry become depleted within the upper 5 m of the sediment. Results of taxonomic and metagenomic analyses indicate that the sediment ferruginous conditions predominantly select for fermentative Bathyarchaeia. Metabolic features attributed to this entirely uncultivated phylum explaining their selective growth were indicative of sulfur transformations, organic matter fermentation and homoacetogenic dark carbon fixation. Thus, Lake Towuti shelters a deep biosphere displaying similarities to early life’s processes in ferruginous systems, which provides a direct link between cryptic sulfur cycling and redox conservative fermentations.

Seismic activity and consistently high CO₂ fluxes make the Eger Rift in Western Bohemia (CZ) a rare subsurface ecosystem and scientifically relevant location to study microbial behavior and assess how geologically derived compound are used in the deep subsurface. Studying microbial life in this ecosystem provides the opportunity to investigate how high CO₂ levels and mineralogy influence microbial community composition and metabolic activity. Seismic activity in this region can also release H₂, a process which may provide the basis for primary production through methanogenic archaea and should be explored.

To assess microbial processes associated with the Eger Rift subsurface we investigated diversity, community structure and metabolic attributes of bacterial and archaeal communities in drill core sediments and groundwater samples. We also analyzed the geochemical conditions in this subsurface system and studied the physiological responses of native Eger microbial communities to high CO₂ via enrichments

Genomic analysis of sediment and water samples, covering depths between 17m and 230m, provided novel insights into a CO₂ adapted microbial community. We detected strong Cyanobacteria and Proteobacteria signatures as well as unexpected archaeal diversity in sediments, and high abundances of acidophiles and sulfate reducers in water samples. Enrichment cultures from the recovered sediments suggested subsurface populations can actively utilize CO₂ and H₂, while reconstruction and annotation of MAGs provided insights into microbial processes driven by CO₂.

Going forward our data will be used to further investigate cellular processes under high CO₂ conditions and identify pathways and biomolecules which may be of industrial and biotechnological relevance.

Material flow data are generally used to assess the environmental footprint of economic activities, e.g. through life cycle assessments (LCAs). This is particularly relevant for the resource-intensive sector of primary raw material extraction and the associated raw material supply chains. As LCAs are firmly established in industry, research, and governmental organizations to support decision-making, e.g. for comparing the environmental impact between recycling processes and primary raw material extraction, an up-to-date and transparent database is the basis for meaningful results. However, the ecological parameters for primary raw material extraction up to refining in the databases often do not reflect the current status. In addition, the data for many metals are often only aggregated values and not available for individual process steps of mining, processing, smelting and refining.

To address this challenge, we conducted a comprehensive survey of emissions data and other project- or deposit-specific data on copper mining, smelting and refining, and correlated the results with currently available general sector data. The data collection was carried out, on the one hand, through a customized questionnaire completed by the companies participating in the studies and, on the other hand, through literature research. The newly acquired project-specific knowledge enables improved calculation of the carbon footprint and greenhouse gas emissions of representative mining projects and smelters/refineries. Furthermore, it serves for a direct analysis of the calculation bases for life cycle assessments and the data on CO₂ emissions of other data providers and their evaluation.

Because of its specific properties, nickel is set to play a key role in the implementation of new megatrends such as the energy and mobility transition. Nickel is used in many industries, primarily in the manufacture of stainless steel and nickel alloys. In addition to these established areas of application, a considerable increase in global nickel demand for battery production is expected until 2030, particularly due to the rapid global ramp-up of electric mobility.

Within this decade the global nickel demand is forcast to double. While the battery production in recent years was based mainly on the dissolution of nickel metal (so-called class 1), things changed in 2022 with intermediates (mainly MHP and nickel matte) representing the by far dominant nickel feed for the batttery production.

Currently, Indonesia is the only country to significantly increase the mine production to provide the necessary nickel intermediates to meet the future demand. Indonesia holds the largest nickel reserves and until 2013 was the worldwide leading nickel ore supplier. With the introduction of an nickel ore export ban, the country became the leading producer of refined nickel products within less than ten years. Moreover, Indonesia is already the by far largest exporter of nickel intermediates for the global battery value chain. However, this dramatic change is based mainly on Chinese investments. It raises questions on the secure and sustainable global nickel supply.

Hyperspectral remote sensing already is important in geoscientific research in the fields of geology, soil, exploration and mining. New hyperspectral satellite systems are already in operation (e.g. EnMAP, PRISMA and DESIS) and more systems are planned e.g. the European Copernicus Next Generation Hyperspectral Satellite CHIME. Investigated are the information contents of hyperspectral data for exploration target recognition and their dependency on spatial resolutions of different sensor platforms. Airborne data offer high spatial resolution of 2.5 m with limited areal data acquisition, whereas hyperspectral spaceborne sensors guaranty nearly worldwide data availability with the same spectral characteristics but medium spatial resolution (30 m). The aspects of high spectral resolution and high versus medium spatial resolution targeted mineral mapping is demonstrated. Hyperspectral satellite data are analyzed successfully to map major mineralogy and proxy minerals such as hematite for the ore mineralization at Gamsberg. The results indicate, that hyperspectral satellite data are an important data source for exploration activities despite the moderate spatial resolution. However, for detailed mapping especially within a mineralization zone, hyperspectral high spatial resolution data from airborne or unmanned aerial vehicle (UAV) systems are important, to understand and to map the mineralogy of such a zone in their complete complexity.

Mechanical excavators have been widely used for the excavation of rocks in mining and civil engineering projects. The excavation of hard rocks by mechanical machines is difficult due to low advance rate and high tool wear. This difficulty can be overcome by exposing hard rocks to microwave energy just before cutting. This paper presents the newly developed a microwave-assisted laboratory hard rock linear cutting machine. The cutting machine which can be equipped with disc cutter or conical cutter has been integrated with a microwave treatment system. The microwave system is composed of 25 kW-magnetron with a frequency of 915 MHz, wave guide, circulator, water load, stub tuner, and directional coupler. A rock sample is first exposed to microwave energy, then cut by cutter using the test system. During cutting tests, normal and cutting forces are measured, and specific cutting energy values are calculated. A preliminary cutting tests were carried out on some rock types using the cutting machine at different microwave power levels. It was observed that the optimum specific energy values ​​of the samples exposed to microwave energy were considerably lower than those that were not exposed to microwave energy. It was also observed that the optimum specific energy values ​​decreased quite steadily with increasing microwave power. The experiments using the new microwave assisted laboratory hard rock cutting machine showed that microwave treatment of rocks before cutting was an efficient method for the excavation of hard rocks.

The growing lithium demand and the dependence on poorly diversified oversea sources point towards a high strategic importance of domestic resources. Furthermore, potentially lower CO₂ emissions and reduced areal use during production favor local co-production of geothermal energy and lithium.

Based on a technology comparison for direct lithium extraction from geothermal fluids and the current state of geothermal energy production in Germany, different scenarios for the extractable amount of lithium carbonate were considered. In the most optimistic scenario, taking into account all currently active wells, a maximum production of 4700 t/a of lithium carbonate equivalent is expected. This could cover 2 – 13% of the annual demand of the planned German battery cell production.

Uncertainties in the resource assessment regarding its size, and the sustainability of its management, are still considerable. Yet a full-scale Li extraction from geothermal brines is missing and thus long-time behavior is not clear. For this purpose, a generical model, based on Upper Rhine Graben geothermal settings was developed, and a Li extraction over a 30-year operation time was simulated. Despite a significant Li depletion, a mean Li production of 231 t/a (1230 t/a LCE) is achieved, for a current state-of-the-art geothermal power plant.

This could significantly increase the economics of a geothermal power plant as well as, if transferred to several plants, a partly independency from global imports. The strongest influence on productivity is the achievable flow rate, which provides access to the raw material, highlighting the importance of good geological reservoir exploration and development.

Highly saline lithium-rich hydrothermal fluids occur in the deep calcareous Muschelkalk aquifer of the northern Alpine foreland basin. We have combined geologic, hydraulic, hydrochemical, and stress field data of the Triassic Muschelkalk aquifer beneath sediments of the Molasse basin of SW-Germany for a synthesis to constrain the origin and development of these brines. In contrast to the regional southeast plunge of Mesozoic and Cenozoic strata, low gradient groundwater flow in the Upper Muschelkalk aquifer is to the north, induced by regional recharge from west, south, and east. North trending maximum horizontal stress axes might provide development of fracture permeability in the competent carbonates of the Upper Muschelkalk aquifer for northward flow. The highest lithium concentrations and total dissolved solids (TDS) can be found in the southeastern parts of the Muschelkalk aquifer, close to the Vindelician High, whereas during northward transport TDS and lithium concentrations are increasingly diluted. We argue that the highly saline lithium-rich fluids originate from fluid-rock interaction of meteoric water with Variscan crystalline basement rocks and entered the Muschelkalk aquifer by permeable faults and fractures. The marginal calcareous sand-rich facies of the Muschelkalk enables the inflow of brines from crystalline basement faults and fractures into the aquifer. We thus argue for an external origin of these brines into the aquifer. Potentials are considered as 100±25 t Li/yr per well.

Lithium mining operations based on direct lithium extraction from brines often use groundwater models such as FEFLOW or MODFLOW for their resource estimation, especially as the amount of extractable lithium (or LCE) depends on how much water can be extracted by pumping wells. At the same time the environmental impact of the pumping (e.g., drawdown) and in some cases the injection (e.g., dilution) needs to be assessed, also using groundwater models.

To effectively use the groundwater models for the mining operation, they should directly be connected to measured data, such as water level data, pumping rates, lithium concentration, to constantly reconcile the measured data with the predictive models. Furthermore, the groundwater model should not be a “black box” that can only be used by specialists, but be interactive and accessible by the mine operators, to run and analyze different mine plan scenarios themselves.

Therefore, an interactive web-based platform was developed based on FEFLOW and MIKE Operations. With the platform the user can, in a simple way, create new groundwater model scenarios by changing pumping rates or adding additional pumping wells, without having to open the software GUI. The model will then run automatically in the Cloud and the results are shown in an interactive map view and dashboard. At the same time the system includes all relevant monitoring and operational data, to easily compare the model data with the monitoring data.

This way the lithium mining operator has the necessary tools and data in one place to make effective decisions.

Batteries are a key part of the energy transition. Lithium(Li)-ion batteries are currently the main source of energy storage in the market and will likely remain so for the foreseeable future. Lithium is currently regarded as a “critical mineral” both for central role in rapidly developing electric technologies and a predicted shortfall in production versus expected demand. Therefore, identification of new resources is both economically and strategically important, driving a boom in Li exploration.

Like other metals, exploration for hard-rock lithium resources faces the challenge of how to bridge scales and dimensions of observations, from field-scale (in 3D-4D) down to laboratory-based imaging and analysis (3D-2D). Moreover, the ability to identify and characterize Li mineralogy present in a sample is important in understanding potential economics of a deposit, including the required mineral processing to extract the Li resource. Combined micro-XRF and Automated Mineralogy (AMICS) is capable of high-speed analysis at the micrometer scale that can identify a wide range of Li mineralogy non-destructively in minimally prepared drill core samples, thus providing valuable information early in exploration. This case study will present mineral characterization from a number of potential lithium resources in Portugal. Preliminary results suggest significant added value of the micro-XRF approach, where a much-improved mineral-textural understanding aids exploration and ongoing evaluation of deposit potential.

Astronomical insolation forcing is now well-established as the underlying metronome of Quaternary ice ages and Cenozoic climate carbon-cycle feedback mechanisms. However, its effects on earlier Eras (Mesozoic, Paleozoic, and pre-Cambrian) are less understood. In this presentation, I will evaluate various pre-Cenozoic modes of response to astronomical forcing, and provide an overview of the Earth System components that were particularly sensitive to astronomical forcing under evolving boundary conditions. Subsequently, the role of astronomical forcing in pacing the global carbon cycle in the Devonian warmhouse and Cretaceous hothouse worlds is discussed. Both periods are characterized by recurrent ocean anoxia and remarkably similar hypotheses exist regarding how astronomical forcing could have amplified a nutrient surplus (from chemical weathering and volcanism, respectively) to tip the ocean system into anoxia. The Triassic-Jurassic boundary cyclostratigraphy illustrates the importance of precession-scale time-control to understand feedback mechanisms and cause-and-effect chains at a resolution that is relevant for making analogies with the present-day. Finally, this presentation provides an outlook on the need for a coordinated approach, using so-called astrochronozones, to establish a fully astronomically-calibrated timescale for the Phanerozoic. Overall, I will highlight the need for a more comprehensive understanding of the role of astronomical insolation forcing in shaping Earth's climate over geologic time.

Sandy alluvial-, deltaic-, and tidal-facies sediments of the Paleoarchean Moodies Group (ca. 3,220 Ma) are preserved several km thick in the central Barberton Greenstone Belt, interspersed with diverse units representing substantial mafic to intermediate (sub-)volcanism. Densely biolaminated sandstones feature common, up to 6 m high fluid-escape structures which fed small sand volcanoes during prolonged and/or recurring discharge of gases, liquids, and solids. The to-date highest documented concentration of fluid-escape structures occurs in a single, largely silicified unit of tidal-facies sandstones ca. 150 m thick, traceable along strike for ca. 14 km and located stratigraphically ca. 1 km above the Lomati River Sill, a 15 km long mafic sill of Moodies intrusive age. Fluid-escape conduits are filled by sand, sericitic clay and fine-grained organic matter. Semiquantitative XRF scanning of several slabbed fluid-escape structures indicates that conduits are enriched in Fe, Cr, Ti, and Mg in comparison to the mean composition of adjacent beds, suggesting that fluid-escape structures may not only have formed due to overpressure build-up from decaying microbial mats in the shallow subsurface but also resulting from release of hydrothermal fluids generated in a thermal aureole above the cooling sill. This inference is also supported by sediment textures characteristic of argillaceous and sericitic alteration, Raman temperatures ca. 50 - 100°C above the regional maximum metamorphic temperature of 320 - 370°C, and associated peperites nearby. Surficial hydrothermal activity in the tidal zone would have likely boosted microbial growth. Surficial pre-compaction carbonation and silicification greatly facilitated the preservation of delicate microbial mats.

The Silurian record in the Siljan crater, Europe’s largest impact structure, in the succession at Baizitian (Sichuan Province) in South China, in other Swedish and Estonian sections, together with records from Laurentia and high latitude peri-Gondwana imply a series of glacial events during the Early Silurian. The associated climate shifts are expressed in stratigraphic sections as δ¹⁸O_apatite anomalies and subaerially exposed sequence boundaries with associated palaeokarst in the tropics and subtropics. During the continuing icehouse after the Hirnantian glacial maximum several stratigraphic gaps developed in the basal Silurian in many parts of the world due to extremely low sea levels, erosion, and first onlaps during deglaciations much later in Silurian times.

Our Telychian to Sheinwoodian chemostratigraphic data include several prominent excursions, such as the pronounced Manitowoc Carbon Isotope Excursion (Manitowoc CIE, ‘Manitowoc Excursion’), spanning the upper Pterospathodus eopennatus Zone and the lower Pterospathodus amorphognathoides amorphognathoides Superzone. Well-bracketed by conodont biostratigraphy, the Manitowoc CIE is an essential tie-point for a detailed correlation between the Baizitian succession in South China and the Telychian strata of Baltica and Laurentia.

Here we focus on the Early Silurian climate development spanning the Telychian Valgu glaciation (more widely recognized than older glacials during the Aeronian), the Manitowoc Icehouse including two short-term glacial events and the late Telychian Glaciation (LTG), , and the Sheinwoodian glaciation reflected by the Sheinwoodian Oxygen Isotope Excursion (SOIE) following directly after the maximum δ¹³C values of the widely known Early Sheinwoodian Carbon Isotope Excursion (ESCIE).

Modern-style plate tectonics is characterized by the global operation of deep and cold subduction involving ultrahigh-pressure and blueschist-facies metamorphism. This is a common process since the Neoproterozoic, but a couple of studies indicate similar processes have been active in the Paleoproterozoic, at least on the local scale. Particularly conspicuous are extreme ultrahigh-pressure conditions of ~7 GPa at thermal gradients <150°C/GPa proposed for metamorphic rocks of the Nordre Strømfjord shear zone in the western part of the Paleoproterozoic Nagssugtoqidian Orogen of Greenland (Glassley et al., 2014). By acquiring a large dataset of heavy minerals (n = 52,130) and garnet major-element composition integrated with mineral inclusion analysis (n = 2,669) from modern sands representing fresh and naturally mixed erosional material from the metamorphic rocks, we here intensely screened the area for potential occurrences of ultrahigh-pressure rocks and put constraints on the metamorphic evolution. Apart from the absence of any indications pointing to ultrahigh-pressure and low-temperature/high-pressure metamorphism, the results are well in accordance with a common Paleoproterozoic subduction−collision metamorphic evolution along a Barrovian-type intermediate temperature/pressure gradient with a pressure peak at the amphibolite−granulite−eclogite-facies transition and a temperature peak at medium- to high-pressure granulite-facies conditions. This is in strong contrast to the proposed ultrahigh-pressure conditions and low geothermal gradients, and challenges the existence of a Paleoproterozoic modern-style plate-tectonic regime in western Greenland.

For a robust interpretation in sedimentary provenance analysis studies (SPA) a combination of multiple methods is usually applied to a selected number of samples. To circumvent effects that perturb the provenance signal (e.g. hydraulic sorting) information on radiometric age, chemical composition and mineralogy is collected for mineral varieties usually by means of laser ablation inductively coupled mass spectrometry (LA-ICPMS), electron probe microanalyzer (EPMA), Raman micro-spectroscopy and polarized optical microscopy.

These methods have become increasingly efficient and allow for rapid analysis of statistically relevant numbers of samples which is fundamental to SPA. However, routine combination of these methods on the same grains is rarely realized and sample preparation quickly becomes a bottleneck when sample numbers are significantly increased. The latter is especially important to detect subtle variations in deposits due to processes operating on centennial to millennial time scales such as rapid climatic variability.

Here we present a workflow that is optimized for high throughput of silt to sand-sized sedimentary samples, which allows routine combination of optical microscopy, Raman micro-spectroscopy, EPMA and LA-ICPMS by means of machine learning methods. Due to the high degree of automatization our workflow enables to access sedimentary archives at high spatial and/or temporal resolution and will provide, depending on combined methods, single-grain datasets that contain information on grain-size, shape, roundness, color, mineralogy, degree of metamictization, chemical composition, trace element composition and radiometric age. We demonstrate innovative approaches in the relevant sample preparation steps and showcase data of several loess profiles highlighting the feasibility of our workflow.

Potsdam the provincial capital of the German state Brandenburg started with an ambitious program to reduce its climate impact about 10 years ago. The program includes the substitution of fossil energy sources for district heating by renewable energy. The investigation of the geothermal potential of the urban area forms an important component of this strategy.

Several deep saline aquifers in the closer surrounding of Potsdam show a potential for a geothermal utilization. They are used for different purposes like natural gas storage (Buntsandstein), underground heat storage (Jurassic), balneology (Rhaetian) or injection of process water (Muschelkalk, Jurassic). The exploration campaign started with 2D seismic measurements which were focused on the investigation of the Mesozoic succession up to a depth of about 2,500 m bgl. Based on the seismic results a drill site was determined where a vertical borehole was drilled into a depth of 2,157 m bgl. The exploration well encountered the succession down to the Muschelkalk formation with partly surprising results. The investigation of the encountered aquifers favoured the further exploitation of the Middle Jurassic Aalenian sandstone as a geothermal reservoir. Accordingly, the second well was deviated to reach this horizon in a deeper situated part of the structure.

Hydraulic tests of the aquifer show promising results with respect to a future use in a local heating system of the surrounding residential buildings. The overrun could be feed into the nearby district heating network. Besides, the results will be used for the development of further locations for a geothermal utilization.

Low enthalpy geothermal systems are well established in north-eastern Germany. The first German hydrothermal doublet started heat production in Waren/Müritz in 1984. Since then other sites in Mecklenburg-Western Pomerania and Brandenburg were explored and realized. Very recently the geothermal heating plant of Schwerin-Lankow has officially started operations and will substitute about 20 percent of fossil energy use in this town.

In most of these projects deep saline aquifers of Mesozoic age were used, which formed in the eastern part of the North German Basin. The well suited reservoir sandstones were often deposited in fluvial and deltaic systems within up to 15 km wide distributary channel belts. The porosity and permeability of channel facies sandstones reach very high values up to 30 % and >6 Darcy, respectively.

On basis of integrated sedimentological-palaeontological investigation and facies analyses using cores and wire logs of numerous deep wells, 15 different stratigraphic channel systems could be detected and mapped (www.sandsteinfazies.de). The results can be used together with temperature distribution data for a first site evaluation. Estimations of productivity and temperature have to be combined with numbers of potential users and existing or planned heat distribution infrastructure in larger communities.

The Geological Survey and ministries of Mecklenburg-Western Pomerania will encourage politicians and decision makers to think about geothermal energy use in their field of responsibility but also support investors to claim for financial support to realize renewable energy projects. This includes open access to available geological and geophysical data according to the Geological Data Act (GeolDG).

The North German Basin yields enormous resources of heat in place bound to the Palaeozoic–Mesozoic succession and to fault systems. Early exploration campaigns have identified highly permeable Mesozoic sandstones at depth of <2,300 m with temperatures of <100°C. Despite the fundamental knowledge established by these campaigns, the development of hydrothermal reservoirs remained limited due to considerable pre-drilling risks resulting from uncertainties in reservoir predictions at individual localities.

To minimise risks associated to subsurface uncertainties, an interdisciplinary work flow integrating sedimentological, geophysical, and petrophysical methods was designed to re-evaluate the six Mesozoic reservoir complexes of the North German Basin. Within the projects Sandsteinfazies, GeoPoNDD and mesoTherm this work flow was applied to an extensive database of cores and wireline logs leading to high-resolution maps depicting facies, thickness and quality of individual hydrothermal reservoirs. These maps enable reliable predictions of key parameters, i.e. net-thickness and permeability, on regional to local scales and, thus, make a significant contribution to the reduction of subsurface uncertainties. The potential of these subsurface reservoir maps to increase the utilisation of geothermal energy is demonstrated on the example of the reservoir development at Schwerin, a previously underexplored locality. There, reservoir predictions enabled targeting a highly productive sandstone at 1,250 m depth. The operation combines a conventional doublet system with industrial heat pumps to supply 7 MW_th to the local heating grid. The lessons learned from Schwerin demonstrate significant opportunities in medium-deep reservoirs enabling a sustained increase of developments for heat supply in North Germany.

This study focusses on Lower Cretaceous sandstone units of Valanginian and Berriasian age in Lower Saxony. The understanding of the distribution and the hydraulic properties of these aquifers is essential to identify suitable areas for geothermal applications. Relevant aquifer units were defined in this study by a significant regional distribution, a thickness of more than 5 m and suitable hydraulic properties.

Three sandstone units can be mapped for the Valanginian stage: The Bentheim Sandstone, the Dichotomiten Sandstone and the so called Hauptsandstein. For the Berriasian stage, the most important sandstone units are the so-called Kopf-Sandstein (Fuhse Formation) and the sandstones of the Basinghausen Subformation. All of these sandstones are located in depths between several hundreds of meters up to 1500 m with a resulting temperature between 30°C to around 50°C.

Aquifers of Valanginian age have the best transmissivities and could be a target for geothermal application. Sandstone units of Berriasian age barely meet the minimum requirements for geothermal use on a regional scale. Nevertheless, suitable aquifer conditions may be developed locally.

All maps of the Lower Cretaceous sandstones can be found at the NIBIS mapserver and the data compilation is free to download. A base map with the relevant sandstone units and all analyzed data points such as well logs, cores and outcrops are available for each geological unit. Parameters for geothermal applications (e.g. depths of the formation, total thickness, sandstone thickness, porosity, permeability and transmissivity) are available as individual layers.

The Mesozoic succession of the North German Basin (NGB) yields enormous resources of heat in place bound to Mesozoic sandstone reservoirs located at depths of up to 2.500 m. Compared to highly-permeable sandstone reservoirs, which are exploited for heat production since the 1980s, carbonate reservoirs are underexplored so far. This study evaluates the potential of Mesozoic carbonates on the example of the Rüdersdorf Formation (“Schaumkalk”) in the subsurface of Berlin/Brandenburg.

The data are based on an extensive bed-by-bed outcrop study in the Rüdersdorf open-pit mine to the East of Berlin, and examination of well cores from Berlin-Spandau and Potsdam. The vertical succession exposed in outcrop and well cores shows gradual transitions from marly limestone background facies (“Wellenkalk”) to thick cross-bedded oolitic grain- to packstone reservoir facies (“Schaumkalk”). Based on analyses of carbonate microfacies and reservoir properties, oolitic reservoir facies exhibit high secondary porosities but low permeabilities. The late-diagenetic dissolution of oolites contributed to oomoldic porosity volumes of up to 27,4 % resulting in the typical foamy texture. But due to matrix-supported grain fabrics, the pore connectivity remained low as emphasized by the permeability range of 0.004–7.7 mD. The potential of the reservoir facies is further limited as fluid circulation along open fractures and faults did obviously not contribute to an enhanced matrix permeability. Accounting for this and the limited lateral extent of thick oomoldic reservoir facies, proven in regional well-to-well correlations, the opportunities for reservoir developments in the Rüdersdorf Formation seem to be very limited.

In Germany the heat demand distribution and operational geothermal production show limited spatial overlap and this is related to the geology in the subsurface. Most of the geothermal energy projects are located in the sedimentary areas of the Molasse Basin, the Upper Rhine Graben and the North German Basin. All these areas have in common that a thermal blanketing effect of young shallow sediments with high porosity keep the heat trapped beneath the insulating porous layer. The North German Basin has an additional heat controlling element - the mobilized Zechstein salt. Salt is thermally twice as conductive as clastic sediments and acts as a chimney for heat transport. The third controlling factor is the basal heat input that depends on the depth to the thermal LAB and the thickness of the upper crystalline crust producing ragiogenic heat, thus adding up to a half to the heat budget in the basins. Finally, the coupled transport of heat and fluid and the composition of the moving fluids add a last layer of complexity in defining geothermal sweet spots. As the fluids can move fast, they can take along their heat/cold, but also may transport solved material that can precipitate and destroy permeability if the PT-regime of the solution changes. The meanwhile increasing resolution of data and structural models of the subsurface open new opposrtunities to simulate heat transport considering the heterogenous physical property distribution as well as physical processes , thus enabling predictions far beyond the interpolation of a few temperatures measurements.

The Global Heat Flow Database (GHFDB) is fostered and maintained by the International Heat Flow Commission (IHFC) for nearly 60 years. During these decades, the technological database concepts and storing capabilities evolved, allowing to add entries in the heat-flow database and underlying scientific methods according to the state of the art and database technology. In 2019, a collaborative database revision process started to provide a quality-assured and authenticated database. The community-driven approach, called the Global Heat Flow Data Assessment Project, started with a discussion of a new database structure to substitute the former database structure from 1976. It was designed to scrutinize and reassess the stored heat flow data according to the new structure. In parallel, the DFG-funded World Heat Flow Database project is developing a modern research data infrastructure for the new global compilation of heat flow data. It will offer comprehensive information on heat-flow related data, publications, projects, and researchers. It is designed to reflect the criteria of FAIR and OPEN data policy and to support the interoperability with other geoscientific data services

Deep geothermal energy (DGE) may play a crucial role in the future energy production considering its base load capacity and ubiquitous availability. The EU Interreg North-West Europe (NWE) funded project DGE-ROLLOUT aims to promote the hydrothermal potential of Lower Carboniferous carbonate rocks, which is investigated following a multi-disciplinary geoscientific approach.

Besides the Geological Survey of North Rhine-Westphalia as lead partner, project partners include the national geological surveys of Belgium, France and the Netherlands, as well as industry partners (DMT GmbH & Co. KG; Energie Beheer Nederland B.V.; RWE Power AG) and research institutions (Fraunhofer Institution for Energy Infrastructures and Geothermal Systems; Technical University Darmstadt; Flemish Institute for Technological Research). Sub- and associated partners include the national geological surveys of Great Britain and Ireland and the European Geothermal Energy Council, amongst others.

DGE-ROLLOUT comprises three administrative, one investment and three implementation work packages (WP T1-T3): T1 provides a reconciled knowledge baseline for the DGE market development in NWE, including a transnationally harmonised depth and thickness map of the Lower Carboniferous. T2 fills information gaps through the acquisition of 2D seismic surveys, drillings, reprocessing vintage seismic data, and developing 3D subsurface models. T3 increases the efficiency of existing geothermal systems, implementing new or improved production techniques regarding reservoir behaviour, cascading systems and thermal energy storage.

As DGE-ROLLOUT comes to an end in October 2023, we are keen on presenting our final results and evaluating the extent to which we succeeded in promoting the DGE potential of Lower Carboniferous carbonate rocks in NWE.

Characterizing the subsurface structural and stratigraphic configuration is critical to address current global environmental challenges such as green energy transition and underground storage. Northern Bavaria, as our case study, is mainly covered by Permo-Mesozoic sedimentary units. Local and regional thickness changes are mainly attributed to the partly exposed structural complexity. To the east, the exposed crystalline rocks consist mainly of metamorphic rocks of Variscan affinity and late to post- orogenic intrusions. The presence and extent of granitic intrusions as a source of heat production and the estimation of the depth to the base of Permo-Mesozoic sedimentary cover are the main objectives of this study.

In this study, we integrate the information from wells and exposed basement geology with reprocessed DEKORP seismic reflection, recently acquired 230 km 2D seismic reflection, Bouguer gravity anomaly and magnetic data to improve our understanding of the structural and stratigraphic configuration of the subsurface in northern Bavaria. Our first results confirm the presence of a granitic body (Hassfurt Granite) as the main source of thermal anomaly observed in northern Bavaria. We also show Permian (Rotliegend) grabens and half grabens storing 1-1.5 km thick sedimentary units. Rotliegend units are covered by relatively tabular Mesozoic cover. In structural point of view, we show that some of the Permian basin bounding normal faults are reactivated as reverse faults during the Cretaceous inversion event. Our observations and models contribute to reservoir characterization (buried fault zones and associated brittle deformation) and reduce exploration and potential future development risks.