Three distinct source areas contributed to sandstones of the Victoria Group within the Transantarctic Basin in southern North Victoria Land. During the Permian, quartzose sandstones were derived from erosion of the local Ross Orogen, likely from an uplifted swell in the area of today's Ross Sea, the Ross High. This source was still active during the sedimentation of lower parts of the Upper Triassic to Lower Jurassic Section Peak Formation. However, at that time the detritus derived from it was mixed with material from a then-active volcanic arc located in Zealandia at the Gondwana margin adjacent to North Victoria Land, indicating that the Ross High was no longer a significant morphological feature. The resulting lithic sandstones interfinger with quartzose sandstones that derive from a high-grade basement source. Within these quartzose sandstones, arc-derived material is a small, but up-section increasing contribution. Most of it is likely to originate from crustal blocks of Zealandia and West Antarctica. As the basin enlarged during its development, the quartzose material became increasingly more widespread in the upper part of the Section Peak Formation.

The 175-year history of the geological societies in Germany began with the aim of promoting geology and all other natural sciences, focusing particularly on the geology of Germany with regard to mining, agriculture and other trades. This practical orientation focused the view on the geological research of the country. The chairmen of the German Geological Society (DGG), which was founded in 1848, were largely state geologists. Against this dominance, the Geologische Vereinigung (GV) was established in 1910 to represent all branches of geology, in particular the interests of general geology, and thus to address interested specialists, teachers and friends of science; it elected its chairmen mainly from among university professors. The separation of Germany into two individual German states after World War II led to the foundation of the Gesellschaft fur Geowissenschaften (GGW) in the eastern country (GDR) in 1954 with the explicit goal of putting the totality of geological research and exploration into practice. The GGW remained an independent society even after the reunification. As the 20th century drew to a close, many economic and ecological issues became more pressing, and the geosciences provided essential insights into these issues. Fragmentation into several geosocieties made dialogue with policy makers and civil society difficult and fostered the desire of many members to merge into a larger geosociety that would, on the other hand, continue to promote diversity in geoscientific research. In 2004, the DGG and GGW finally merged into the German Society for Geosciences (DGG-new), which fused with the GV in 2014 to form the German Geological Society (DGGV).

How can inorganic geochemical data from terrestrial deposits be used as a provenance tool? We demonstrate a new approach as earlier studies have focused on marine deposits. We present a review of the factors that affect the whole-rock geochemical composition of terrestrial deposits and a case study to test how geochemical provenance differentiation can be made for such deposits. We confirm that both K2O/Na2O and immobile trace-element ratios are suitable provenance indicators for terrestrial deposits. We stress that previously developed discrimination schemes constructed for marine deposits of different depositional facies, specific grain size and texture (commonly greywacke) for identification of tectonic settings are unsuitable for terrestrial deposits as they often are related to different tectonic frames, depositional facies, and sorting degrees. Different terrestrial tectonic situations will influence the detrital composition such that rift, foreland, and sag basins likely have different chemical compositions. Humid climatic conditions may reduce such differences.The case study is based on the intracontinental Permian Rotliegend Group and Early Triassic Buntsandstein Group and equivalents in central Europe, mainly Germany and Denmark. Both units had mainly felsic sources. We present results from >1500 sedimentary samples from both published and unpublished data, mostly from sandstone. K2O/Na2O efficiently differentiates sandstone from different regions. The compositional variation is in line with reported variations in feldspar compositions and indicates local catchments. Thus, the feldspar has been preserved in the arid climate due to limited weathering. Y/Co, in combination with other indices (La/Sc, La/Lu, Ti/Nb, Th/Sc), is one of the most successful mafic-felsic trace-element indices that we use. We postulate that the trace-element variation is governed by mineral inclusions mainly in feldspar in addition to individual detrital grains. V/Zr and Zr/Sc mostly correlate with Y/Co, which indicates different zircon affinity in the source rocks rather than sorting. More dominance of felsic compositions and higher Zr/Sc for Triassic than Permian strata are in line with more sedimentary recycling during the Triassic than Permian. Thus, the results reveal that source-rock differentiation can be made for different geographical areas and stratigraphic units based on K2O/Na2O due to variations in feldspar compositions in the source areas, provided little chemical weathering. Based on the case study, the mafic-felsic trace-element ratios La/Sc, Th/Sc, Y/Co, and Ti/Nb seem most promising for provenance discrimination, in combination with La/Lu, and Zr/Sc and V/Zr as tracers of heavy minerals. We conclude that the combination of arid climatic conditions and terrestrial depositional environments makes it possible to use both major oxides and trace element ratios to reveal source-rock differences. For robust provenance interpretations, we recommend to focus on immobile elements that are little affected by grain-size variations, to combine several element ratios for interpretation, to avoid comparison of data produced by different methods (for instance x-ray fluorescence and mass spectrometry), and to complement geochemical investigations with data from other methods.

The Lower Triassic Buntsandstein in Central Germany comprises one of the major clastic, lithified hydrocarbon reservoirs, it is a major groundwater aquifer and it is considered as a potential underground gas storage lithology. Thus, sandstones of the Buntsandstein from Thuringia and NE Hesse were used to analyse their geochemical composition combined with mineralogical data in order to investigate the origin of several bleaching phenomena in primary red beds, since these give a hint for mineral alteration, mineral formation and mineral reactivity in the course of fluid-rock-interactions. This is relevant for e.g. recent Carbon Capture and Storage (CCS) efforts. The origin of the observed bleaching phenomena is diverse and it is linked to certain stages of diagenesis and different episodes of fluid flow: (1) eodiagenetic bleaching coupled with palaeosoil formation and iron mobilisation, (2) mesodiagenetic bleaching as a result of hydrocarbon migration, (3) Tertiary bleaching due to CO2 degassing from Miocene volcanism, (4) Tertiary telodiagenetic bleaching due to weathering under humid climate conditions, and (5) weathering processes related to recent telodiagenesis/pedogenesis. This study emphasizes the multiple nature of fluids, which can induce iron mobilisation and bleaching of red beds.

The Lower Triassic Buntsandstein is an economically important clastic underground reservoir and aquifer unit in the Central European Basin (e.g. for hydrocarbon reservoirs, gas storage, geothermal energy use, drinking water supply). Its quality mainly controls its prospectivity, storage capacity and exploitability. Thus, predictions for the realization of economic intentions depend most notably on a substantial understanding of the parameters that control reservoir quality, such as facies and diagenetic alterations resulting from fluid-rock interaction. Therefore, research of even small-scale relationships between hydraulic heterogeneities and rock properties is necessary. The study area is the Thuringian Syncline, which is a small sub-basin of the North German Basin located at its southern margin. One of its major aquifers is built from siliciclastic sediments of the Buntsandstein, which are characterized by rapid changes of depositional environments from channel to sandflat to lacustrine depositions resulting in large heterogeneities at a relatively small scale (few to some hundred meters). Furthermore, burial history and subsequent basin inversion and uplift led to only minor depths of 700 to 1000 m in the center of the syncline and an exposure at the surface at syncline margins, which allows for the exploration of the recent impact of meteoric water infiltration vs. former burial evolution on aquifer quality. We combined a petrographic study focusing on mineral composition and diagenesis with a study of depositional facies and linked the results with petrophysical data like permeability and porosity. The corresponding dataset consists of measurements on more than 300 plug samples from 12 wells and additionally more than 400 thin sections. All in all, the Buntsandstein exhibits a very complex relationship of hydraulic parameters with diagenetic evolution in relation to depositional preconditions. For example, high amounts of channel deposits in the sandstones result in better aquifer qualities. The same holds true for increasing grain sizes. Finally, there is a major influence of telodiagenetic processes and meteoric water infiltrations. Thus, major pathways for fluid flow are not solely controlled by sedimentary facies, but also by present-day cement dissolution and mineral alteration, especially in the vadose zone.

Mainly acidic Stephanian to early Permian volcanic rocks and intercalated sediments accumulated in the Thuringian Forest Basin (TFB) in central Germany to a total thickness of ca. 2000 m. This basin offers a wide range of biostratigraphic information. New high-precision U–Pb CA–ID–TIMS (chemical abrasion–isotope dilution–thermal ionization mass spectrometry) zircon data are obtained from volcanic rocks for the first time in the TFB. Pre-treatment of the zircons by chemical abrasion was important to get rid of severe Pb loss. The zircon ages of the investigated formations indicate that the total duration of the volcanic activity in the TFB was considerably shorter [ca. 4 Myr: from 300 Ma for the oldest formation (Möhrenbach) until ca. 296 Ma for the youngest volcanic-rock-bearing formation (Rotterode)] than suggested in previous studies (ca. 20 Myr; 295 Ma to 275 Ma). Consequently, the well-documented gap of the sedimentary record from the early Permian volcanic rocks up to the Illawarra geomagnetic reversal has to be extended to ca. 25 Myr from the previously proposed 5 Myr. The zircon ages of the investigated volcanic rocks allow the constraining of some intercalated fossiliferous horizons crucial for biostratigraphic correlation of latest Carboniferous–early Permian (Rotliegend) sections. The high-precision age data require a new interpretation of the evolution of the TFB but also offer the chance to obtain a more reliable comparison of the timing of the main magmatic activity across intramontane basins as well as to obtain links to the Standard Global Stratigraphic Scale.

The eolian-fluvial sandstones of the Upper Permian Rotliegend formation, which were deposited in the Southern Permian Basin, are today deeply buried (similar to 3-4 km) and constitute important gas reservoirs in the Netherlands and the southern North Sea. The reservoir properties of the sandstones have been documented to be strongly affected by diagenesis, but the primary diagenetic factors impairing reservoir quality and their cause remain variably interpreted in the literature. Here, we present the results of a detailed investigation on the diagenetic processes controlling reservoir quality in the Lower Slochteren formation in the L and K blocks offshore the Netherlands, where fluvial and aeolian sandstones intercalate with playa lake muds in a delta setting. Quantitative analysis of the diagenetic mineral phases occurring in all main depositional facies (eolian, fluvial, playa-lake) was carried out on more than 200 samples from 21 wells, with the authigenic mineral composition of an additional 500 samples being evaluated qualitatively. The integration of petrographical observations with log data and core descriptions reveals that cement distribution/abundance is not dominantly driven by depositional facies, nor are reservoir properties. Early pore-filling dolomite cement can be as high as 40% and represents the main control on reservoir properties. Detailed analysis of its spatial distribution shows it to be distinctly related to mudstone proximity and mudstone/sandstone (M/S) ratio. Sandstones occurring as thin beds in mudstone-rich depositional sequences (high M/S ratio) typically exhibit strong pervasive carbonate cement regardless of sedimentary fades. In contrast, sandstones forming thick beds in mudstone-poor sequences (low M/S ratio) are commonly free/low in dolomite cement. Our results demonstrate, for the first time, that reservoir quality in the Rotliegend sandstones in the delta setting of the Netherlands is primarily controlled by early dolomite cement. The latter is most developed in areas with high (> 70%) vertical M/S ratio, where it may be a devastating factor for reservoir quality. Best reservoir sandstones should be expected where the depositional stacking pattern is poor in shaly deposits (playa-lake and distal sheet-flood sediments), such as in the southern/south-eastern part of the studied area.

The geodynamic activity of the NW-Bohemia / Vogtland region with its earthquake swarm activity is always studied in relation to the local emission of juvenile fluids, in particular of CO2. Based on a 3D interpretation of the geological setting, geophysical results, and new evaluation of existing data, our approach suggests a spatial separation of the upper crust into areas with differing pore fluids. The first area comprises a mixture of juvenile and meteoric pore fluids, where juvenile CO2 diffuses towards the surface. The second area exclusively contains meteoric and no juvenile pore fluids. It is in this area where the earthquake swarm activity occurs. This separation provides an important constraint which influences shear processes as the contrasting fluid chemistry induces different interaction of wall rock with pore fluids. Long-lasting chemical degradation of the wall-rock with clay as a typical alteration product in crustal volumes with pervasive CO2 discharge reduces the friction coefficients resulting in the weakening of the fault zone and allowing an aseismic slip according to the stress field. The presented studies suggest that the junction of two regional geological features of crustal scale, the N S trending seismically active Leipzig-Regensburg-zone and the NW-SE trending fluid emission zone of magmatic volatiles, can be interpreted as a transition from frictional slip in the recent focal zones to aseismic behavior towards the southwest caused by clay coatings on the shear planes induced by a CO2 containing pore fluid.

A combined study of facies and diagenesis variations was carried out with the aim to understand small-scale heterogeneities in porosity and permeability of sandstones within a 219 m completely cored Middle Buntsandstein succession from central Germany. The well Erfurt 1/12 (EF-FB 1/12) allows studying aquifer quality variations by taking 49 plug samples of fresh rock material for thin section analyses and petrophysical measurements. This potential Buntsandstein aquifer is composed of varying portions of sandstones, mudstones and sand-stone-mudstone interlayers, which were deposited on a large terminal fan system and in a large playa-lake in the basin centre. A fluvial channel and a sandflat depositional environment can be distinguished. Both are composed of varying amounts of channel-, sandsheet- and floodplain sediments of mainly massive, cross-bedded, horizontally laminated and ripple cross-bedded sandstones. Best aquifer potential occurs in the horizontally laminated and cross bedded sandstones within channels of the fluvial environment, and in the massive sandstones of channels in sandflat deposits. Aquifer quality does not decrease with increasing depth or stratigraphic position. Instead, it is controlled by grain size and diagenetic evolution. Four diagenesis types were distinguished: (1) cementation type (CT), (2) leaching type (LT), (3) illite type (IT) and (4) mixed type (MT). Best aquifer quality was found in the leaching type (LT) consisting of larger grain sizes (medium sand), which led to the formation of a large primary pore network. Our data suggest a strong relation of hydraulic parameters not only with different facies types, architectural elements and depositional environments, but particularly with compaction and cementation during burial, and dissolution by meteoric water during subsequent uplift history. Thereby, present horizons with good hydraulic properties relate to this complex interaction of sedimentary facies and diagenetic evolution, but are restricted to only very local areas with no relevance for basin-wide fluid flow in the subsurface.