Volcanic and sedimentary rock successions of the Oderen Group in the Southern Vosges Mountains (Lower Carboniferous) have been analysed with regard to facies, depositional environments and the former spatial relation between sedimentary and magmatic domains. Fifteen lithofacies assemblages reflect the physical stratigraphic framework in space and time. Basin analysis is combined with published geochemical and geochronological data from magmatic suites of the Southern Vosges. As a result, this work comes up with a basin-dynamical and tectonic scenario, which is compared with current models of the crustal reorganisation in Variscan time that took place following the Devonian plate collisions. Mafic plutonism in an extensional regime and submarine tholeiitic to low-K-calcalkaline volcanism with pillow basalts started at ca. 345 Ma BP in the lower Visean. Enhanced subsidence is documented by mud-rich deep-marine gravity flow deposits with considerable thickness in a slope and basin plain environment. Repeating cycles of pillow basalt and tuffaceous quarzitic turbidites accumulated to great thickness in a fore-arc setting together with deep-marine volcaniclastic gravity flow deposits. A further thickening of the arc-ridge during the middle Visean (ca. 340 Ma BP) led to a medium to high-K-calcalkaline intermediary volcanism located in an upper slope and outer shelf setting. Convergent movements and rising of mantle derived monzogranitic magmas became more dominant due to ongoing collision, leading to a high-K-calcalkaline to shoshonitic explosive volcanism and to basin inversion with delta progradation between ca. 339 and 337 Ma BP in the late Visean. The volcanic evolution in a fore-arc-arc-back-arc basinal configuration shows classic geochemical indicators for subduction-related environments influenced by juvenile crust. In analogy to theories on the geodynamic evolution of the southern Tyrrhenian Sea, a deepening of the Oderen Basin with SE-NW polarity in response to lateral escape tectonics is discussed. Whereas slab roll-back and mature back-arc extension in the wake of the Devonian closure of narrow ocean basins are critically viewed for this time, the geological data from the Southern Vosges remains fully consistent with a highly mobile basement behind an extrusive wedge, which evades at the expense of low buoyancy lithospheric domains, and with syncollisional supra-subduction magmatic processes. The presumed original extent of the identified parts of the basin contrasts sharply with the exceptionally small distance between the individual domains exposed today. Successive deformation processes in a lateral escape setting, including dextral strike-slip faulting, folding and steepening of the strata, block-rotation, and transpressive thrusting are able to explain the extreme telescoping of the basinal domains which took place in a short period of time in the late Visean. Field data argues in favour of a fold and thrust belt, which collapsed by extensional detachment and late transtensional shearing and rifting. The new perspectives on the construction and evolution of the Southern Vosges presented here highlight the particular importance of the volcanic and sedimentary rock sequences for understanding the late Variscan evolution in its internal zone of Central Europe.
Within the framework of the industrial transformation ("Strukturwandel") in the Rhenish Lignite Mining Area, alternative heat sources are becoming increasingly important to meet municipal heat demand. This need becomes even more pressing with the phase-out of the lignite-fired coal power plant in Weisweiler in 2029. It currently provides approx. 165 MWth of heat to district heating networks in the Rhenish Lignite Mining Area. The development of medium-deep (>400 m) and deep geothermal reservoirs (> 1,500 m) could be a partial solution to provide renewable heat to single buildings, residential or commercial neighbourhoods, or districts of the city of Aachen via the existing district heating network. Two exploratory wells (EB1 and EB2) were drilled next to an existing drill site by RWE Power AG within the exploration framework for geothermal energy and the construction of new research facilities on the premises of the power plant in Weisweiler. The first well, EB1, was drilled in October 2023 with a measured total depth of 100 m while the second one, EB2, was drilled in February 2024 with a measured total depth of 506 m. EB1 was equipped with a 3-component seismometer while a double-U heat exchanger was installed in EB2. Both boreholes are equipped with fibre optic cables along their entire length. An enhanced geothermal response test to estimate the effective thermal conductivities was performed in the second borehole. The cuttings, the core material, and geophysical logs provide information about the distribution of Cenozoic and Palaeozoic deposits of the Weisweiler Horst of the Lower Rhine Embayment. The Palaeozoic deposits of the Inde Syncline of the Rhenohercynian Fold-and-Thrust Belt are encountered at a depth of approximately 70 m. The observations enable the characterisation of depositional sequences (cyclothems) of the Upper Carboniferous and support the evaluation of the structural and petrophysical properties of the encountered alternating layers of mudstone, siltstone, sandstone, and hard coal. Current structural geological models of the area can now be revised to include the more certain stratigraphic boundaries of the Breitgang and Aussenwerke formations. Similarly, it will be possible to recalculate the depth distribution of the Lower Carboniferous Kohlenkalk carbonates by performing an uncertainty analysis. These boreholes mark the initial phase of geothermal exploration of the potential reservoirs around Weisweiler. Seismic campaigns and deep exploration wells are planned to continue exploring the subsurface of the region in the coming years.
The German part of the North Sudetic Cretaceous Basin at the northern margin of the Lausitz-Krkono & scaron;e Massif comprises an up to over 1,100 m thick, predominantly marine succession of Upper Cretaceous (Cenomanian to Santonian) deposits. Strata on the German side of the basin are mainly represented by thick, bioturbated marls and calcareous siltstones ('Pl & Oslash;er'). Hemipelagic limestones and shallow marine sandstones occur in specific units close to the base and at the top of the succession, respectively. Because little stratigraphic work has been conducted since the 1970s, basin architecture, facies evolution, and provenance shifts on the German side remain only poorly constrained. In search of a nuclear waste disposal site in Germany, this petrographic study explored the composition and texture of diverse sedimentary rocks from various stratigraphic levels of cored exploration wells. New petrographic and geochemical analyses indicate a wide variety of lithologies, volumetrically dominated by bioturbated, calcareous siltstones with varying clay and sand contents. Rapid transgression from the Cenomanian onward facilitated the formation of significant hemipelagic carbonate deposits during the maximum extension of the Cretaceous Sea in the Turonian. After the deposition of Lower to Mid-Turonian calcareous marland limestones, increasing siliciclastic input and accommodation space were expressed in hundreds of metres of marly to sandy calcareous siltstones ('Pl & Oslash;er') from the Late Turonian till the Coniacian. The Coniacian pelitic deposits interfinger with sandstones toward the southeast, which dominate the whole section in the Polish part of the basin. Deposition of marine, glauconitic sandstones on the German side resumed in the Upper Coniacian. The Lower and lowermost Middle Santonian are dominated by (sub)litharenites that were succeeded by more quartzose counterparts during the Middle Santonian. The expression of Cretaceous sandstones thereby reflects the spatiotemporal changes in source rock supply. The Cenomanian marine complex starts with a few metres of glauconitic hybrid arenites (Gro ss-Rackwitz Formation). Abundant lithoclasts were eroded from underlying Upper Palaeozoic and Mesozoic sediments and cover rock on nearby palaeogeographic highs. The exhumation and redeposition of an older sedimentary basin was followed by a fresh influx of low-to medium-grade metamorphic rock fragments from the West Sudetic Island (the proximal G & ouml;rlitz Slate Belt/westernmost Kaczawa Complex and adjacent Jizera-Krkono & scaron;e Block) or metapelites from the Fore-Sudetic High that had gradually reached the erosion level by Coniacian and Santonian times (likely the upper Kohlfurt Formation). Subsiding input of metamorphic lithoclasts and novel quartz fractions in the quartzose arenites of the Tschirndorf Formation agree with progressive unroofing of the West Sudetic Island and shifting sediment supply toward granitic provenance.
With the abandonment of hard coal mines, mine flooding is typically initiated. This increases the subsurface pore fluid pressure and may induce seismicity. In this study, we aim to understand the origin and spatiotemporal occurrence of post-mining microseismicity in the Saar hard coal district in SW Germany detected between 2013 and 2018. For this purpose, we construct a structural geological 3D fault model and evaluate the fault reactivation potential under the influence of increased pore fluid pressure. The 3D fault model reveals several sub-basins bounded by NE-SW striking normal faults and NW-SE striking transfer faults. Microseismic events are mostly characterised by small magnitudes M-L < 1 and shallow depths between-1.0 and-1.5 km below sea level. The highest microseismic activity (i.e. number of events) was observed during periods with the highest flooding rates measured at shaft Nordschacht indicating fluid-induced microseismicity. In conclusion, (1) the post-mining phase is seismically less active (<= 16 events per month, M-L <= 3.0) than the active mining phase (tens of events per month, M-L <= 4.0) and (2) slip tendencies as well as scaling relationships indicate that large-scale faults (offsets >= 10 m) were not reactivated. Instead, microseismic events may be associated with small-scale fractures (off-sets < 10 m).
After the Second World War, the state geologist Werner Paeckelmann was actively involved in the reconstruction of the Geological Survey in Berlin. In 1946, he was arrested in the eastern part of the city and sentenced to ten years' imprisonment by a Soviet military tribunal in 1947 for alleged espionage. He died in custody in 1952.
Aus der Geologie des Elbtalschiefergebirges lassen sich zwei aufeinanderfolgende tektonische Zyklen ableiten. Begleitet von bimodalem Magmatismus erfolgt im sp & auml;ten Devon eine Differenzierung der marinen Fazies. Die sich anschlie ss ende niedriggradige Regionalmetamorphose spiegelt Krustenstapelung w & auml;hrend der variszischen Gebirgsbildung wider. Der zweite Zyklus wird durch die diskordante Ablagerung unterkarbonischer synorogener mariner Sedimente auf dem exhumierten Krustenstapel eingeleitet und ist durch eine erneute Versenkung und eine heterogene dextrale transpressive Deformation gekennzeichnet. Die Scherung an der nord & ouml;stlichen Grenze wird von einer prograden Hochtemperatur-Regionalme tamorphose begleitet, die mit der Platznahme der synkinematischen Mei ss ner Granitoide assoziiert wird. Die Bildung der Mittels & auml;chsischen Scherzone im S & uuml;dwesten steht im Zusammenhang mit der finalen Nebeneinanderstellung des Erzgebirge-Komplexes mit dem Elbtalschiefergebirge in der Oberkruste. Die postkinematische Intrusion des Markersbacher Granits, die Platznahme sp & auml;tkarbonischer Rhyolith-G & auml;nge sowie die diskordante Ablagerung permokarbonischer Sedimente des D & ouml;hlener Beckens markieren das Ende der durchgreifenden dextralen Scherung im Elbtalschiefergebirge.
The geothermal reservoir in the Eastern Molasse Basin is mainly located in Kimmeridgian dolomites, which have different genesis, as documented in the present study. Different diagenetic pathways from primary carbonate sediments with associated sponge-algal mound facies to deep buried dolomite in the Molasse Basin lead to dolomite with different reservoir properties (porosity, permeability). Based on five previous studies that provide data on microthermometry isotope ratios (delta O-18, delta C-13) and burial depths, the formation of dolomite can be assigned to different eogenetic and mesogenetic phases. Early matrix dolomite and dolomite bound to organic material (sponges, microbial layers) were formed during eo-to shallow mesogenesis at a burial depth of up to 1,000 m and at temperatures of 40-70 degrees C and 60-90 degrees C. The first light overgrowths on dolomite crystals are also assigned to this phase. In the shallow mesogenetic phase, intensive dolomite formation took place at depths of up to 2,500 m and temperatures between 70-100 degrees C. Dolomite overgrowth is ongoing, resulting in zoned dolomite crystals with fine-crystalline, inclusion-rich cores and light seams of overgrowth. Deep mesogenesis is characterised by intensive recrystallisation of the dolomites at > 2,500 m depth and temperatures of 100-150 degrees C. Intense compaction also takes place, which leads to the partial dissolution of dolomite crystals including their overgrowths seams. The dolomite structure is compacted and porosity and permeability are extremely reduced, as can be concluded from microstylolites on dolomite crystals. The investigation results from four boreholes (Unterf & ouml;hring Th3, Pullach Th3, Sauerlach Th3 and Geretsried Gt1), which lie approximately on a N-S line, reveal the spatial effects of these processes. The Mg-rich pore solutions due to the pressure solution migrate to northern, structurally higher positions and lead to the formation of dolomite cements ("overdolomitisation"), which close still open intergranular pores. Therefore, the dolomite reservoirs in the northern, less submerged area of the Eastern Molasse Basin still have favourable reservoir characteristics, while to the south the dolomites become denser with increasing burial. The reservoir properties are extremely reduced at depths of > 5,000 m and only dense dolomite is present. Here, only fissures serve as pathways for geothermal water. These processes are also strongly dependent on the early facies and genetic parameters, which were effective down to a depth of about 1,000 metres. Therefore, it is dolomite formation in the Eastern Molasse Basin represents a complex system of early facies influences, overprinting, alteration and cementation in the different phases of subsidence, which is still active today. Therefore, is important to recognise the early genetic parameters to understand the subsequent burial development, even if only ghosts structures are preserved.
Understanding hydraulic conductivity is essential in porous media because it dictates how fluids flow through these materials, playing a crucial role in various environmental and engineering processes. It serves as a fundamental parameter that characterises permeability, impacting fields like hydrogeology, soil science, and civil engineering by facilitating precise predictions of water movement, contaminant transport and groundwater flow. In the present study, a machine learning technique Support Vector Machines (SVMs) was utilised to predict the coefficient of hydraulic conductivity along the bedding plane based on influencing factors such as water content, void ratio, specific gravity, liquid limit, plastic limit, shrinkage limit and angle of orientation. Statistical analysis demonstrates that the SVM model 4 proposed aligns well with experimental data (R2 = 0.99 and RMSE = 1.03 x 10-4) and surpasses other conventional methods in accurately forecasting hydraulic conductivity along the bedding plane. This study highlights the effectiveness of employing machine learning in analysing stratified porous media.
A geological survey at the 1:10,000 scale was performed in the Farma River Valley, the central part of the late Palaeogene-Quaternary Monticiano-Roccastrada metamorphic core complex (MRMCC), Tuscany, Italy. The area is subdivided by complex first-order faults into tectono-stratigraphically homogeneous subzones, characterised by distinctive Carboniferous lithofacies and by late Palaeogene-Quaternary deformation and metamorphism. The uniform stratigraphic base is formed by a condensed interstratification of carbonous mudstones, fine-grained greywackes and cherts (late Emsian-early Tournaisian), which were deposited in a shallow epicontinental starved basin. Subsequent extensional fragmentation produced coeval, predominantly siliciclastic depositional areas. The sediments form progradational highstand systems tracts above a downlap surface, which represents the floor of the shelf, the lower slope, the base of the slope and the margin of the basin floor. The mobilisation of the sediments via tempestite-turbidite cycles was probably triggered by a hothouse pulse, related to the Hangenberg Crisis. The coeval units created were covered uniformly by regressive, littoral-deltaic and continental siliciclastics (Permian to middle Triassic) and subsequently formed the substrate of the Mesozoic, transgressive, passive margin deposits of the Adriatic microplate. Oligocene to Miocene thrusting-and subduction-related tectonic burial to a depth of ca. 25 km, followed by Miocene to Pliocene extensional exhumation, was controlled by several shear zones, including the reactivated Carboniferous normal faults mentioned above. This resulted in the formation of closely spaced interfering metamorphic core complexes. Post-Messinian oroclinal bending caused the intense fragmentation of the subzones. The Farma River Valley is interpreted as the geomorphological expression of exhumed tear faults, which were part of the fracture system controlling the late Tortonian-Quaternary eastward-migrating Tuscan Magmatic Province.
On the occasion of his 80th birthday on March 25, 1880, the miner and geologist Prof. Ernst Heinrich Carl von Dechen, received an elaborately crafted memory chest from the members of the German Geological Society (DGG), decorated with silver fittings and numerous semi-precious stones. What was special about this chest, however, was its content. A total of 210 people who were members of the DGG in 1879/early 1880 are depicted on 51 panels, each with four photographs. After Heinrich von Dechen's death, the memory chest was lost. It was not until 1951 that the DGG learned again of its existence and the historically valuable content for the DGG. The Society initially received an offer from an antiques and art dealer to purchase the unique photo collection. Shortly afterwards the Society was offered a "Scottish watercolour", which was also in the chest. In March 1951, the DGG first acquired the photo collection in the chest and finally the memory chest in September of the same year. In 1983, the chest was handed over to the then BEB Petroleum Natural Gas Company (Brigitta and Elwerath Betriebsf & uuml;hrungsgesellschaft mbH unions) for safekeeping. Afterwards, the memory chest was forgotten again. Then, in 2005, the memory chest was rediscovered by chance in the company's vault, restored and then exhibited at the BEB. The DGGV learned of the "treasure find" from a report in the BEB's company magazine ("maGASin"). After the exhibition finished, the chest found its way back to the DGG, or today's DGGV, after 145 years.
We have re-investigated the extent of the Rhine Glacier in the Alpine foreland of eastern Upper Swabia (Germany) during the Late W & uuml;rmian glaciation (Last Glacial Maximum). Decades of research had failed to produce agreement on the position of the glacier and the sequence of events at and following full glaciation. The availability of very high-resolution LiDAR-based digital terrain models greatly facilitated our analysis and interpretation of landforms and their patterns. As part of our research new observations of the sediment types underlying the landforms were made in actively mined gravel pits, and were combined with prior observations extracted from literature in the case of abandoned pits and past outcrops in restored landscapes. Integrating the two datasets we were able to obtain fresh insight into the main depositional processes, the position of former ice margins and the sequence of events, resulting in a robust morphostratigraphy. Glaciofluvial processes rather than glacigenic processes dominated the ice-marginal environment, with occasional but important contribution from rivers of the ice-free terrain. Throughout the study area an advance of the glacier beyond the outermost ice-marginal position ("& Auml;u ss ere W & uuml;rm-Endmor & auml;ne") as originally interpreted by Penck & Br & uuml;ckner (1909)-an issue already proposed in the literature of the 1950s-could be confirmed and substantiated by the sedimentological and geomorphological data. We discern four stages: 24 ka event, recession to 23 ka margin, 23 ka event, and recession from 23 ka margin. In many places the precise position of the ice margin of the 24 ka event is difficult to determine due to the fragmented nature of the data. However, the occurrence of dead-ice features, buried deposits and occasional ice-marginal ridges documents its existence throughout the area. During the recession from the 24 ka margin to the margin of the 23 ka event large quantities of dead ice remained behind, resulting in extensive dead-ice kettle fields; the high-resolution digital terrain models now allow their recognition. The 23 ka margin resulted from an important phase of standstill during the initial recession of the glacier and is defined by a few well-developed ice-marginal ridges, but mainly consists of broad hummocky ridges. During the subsequent recession of the glacier, these landforms were partly affected by substantial (glacio)fluvial erosion and reworking.
This work provides German translations and definitions of English terms used to describe fractures, faults and fracture networks. This includes faults, joints and veins. The terms are separated into four categories as appropriate to their usage for geometrical, topological, kinematic or mechanical properties.
Joint petrophysical, geochemical, and petrographic studies on Barremian carbonate rocks from the Gagra-Java Zone at the transition of the Central Greater Caucasus to the Rioni Basin in Georgia are rare and almost absent in literature. In a joint research project between Georgian and German research institutes, this work showcases the first consistent dataset on rock properties, which are the foundation of the Enguri High Arch Dam, a large and regionally important energy infrastructure. The studied carbonate rocks from a 307 m deep research well are subdivided into two carbonaceous and two dolomitic sections, exhibit intense brecciation, represented by multiple rubble zones. Petrographic analyses in conjunction with petrophysical sample analyses do not show a clear correlation of rock properties to the rock's microfabric. Generally, matrix permeabilities are low to very low (< 10 mD) and do not correlate with matrix porosities. Elevated matrix permeability is only found in samples from the topmost 120 m of the studied well, but is not restricted to samples exhibiting carbonate mineral dissolution (mostly dolomite dissolution), which can be observed along the whole studied well. Based on cathodoluminescence analyses eight distinctly different phases of carbonate cement precipitation in brecciated sections and fractures can be distinguished and related to faulting and compressive tectonic phases resulting in the formation of stylolites. The analyses are supplemented by first UCS measurements (ranging from 19.9-175.0 MPa) to gain a better understanding on the mechanical properties of the studied samples.
canic field (Germany) based on their morphological and microstructural characteristics. One generation consists of subhedral prismatic amphibole crystals exhibiting concentric zoning and cloudy interior zones. Their growth was followed by corrosion and melt infiltration. This generation is interpreted as phenocrysts that nucleated in the basanitic melt and grew until disequilibrium between crystals and melt occurred. A second generation of amphibole consists of smoothly rounded, optically clear, and unzoned crystals. Internal corrosion is absent; rather, the surfaces of the crystals became smoothly rounded by resorption in the melt. This generation is interpreted as antecrysts incorporated by the basanitic melt while it was still undersaturated with respect to amphibole. The greater resistance of antecrysts to internal corrosion, compared to phenocrysts, is best explained by their more perfect crystal lattice-low in defects and impurities-formed during slow, near-equilibrium growth in deep-seated melt pockets. A third generation of amphibole is represented by rare coarse-grained oligocrystalline aggregates. They exhibit undulose extinction, low-angle grain boundaries, and carbonate inclusions. These aggregates are interpreted as fragments of ultramafic xenoliths that underwent ductile deformation prior to incorporation into the basanitic melt.
A new temporary section of the Olenekian upper Volpriehausen Formation (Middle Buntsandstein) is described from the Hildesheimer Wald Anticline (Lower Saxony, Germany). The section comprises an alternation of reddish-brown, thin-bedded fine-grained sandstones, argillaceous sandstones (heteroliths) and siltstones, which show monospecific assemblages of either small, disarticulated bivalves (Pteria murchisoni) or conchostracans (Branchiopoda). As an exception, a greenish-grey bed with limulid carapaces and larger, articulated Pteria murchisoni, load casts, and convolute bedding is intercalated. Fora better understanding of the depositional environment, ripple measurements from three bedding planes were carried out. Ripple indices and ripple symmetry indices demonstrate that most ripples fall within the zone of asymmetrical oscillation ripples and the transition zone to current ripples. All the data indicate a deposition of the corresponding sandstone beds in a very shallow, current-affected setting, consistent with marine-microtidal as well as lacustrine environments. The exceptional pteriid-limulid-bearing sandstone bed may have formed by a storm or flooding event. Two beds with halite crystal marks indicate at least temporary saline conditions, as do specific acritarchs from the same stratigraphic unit of other sections. The marine or non-marine nature of the Pteria murchisoni habitat remains to be shown by further palaeontological and palaeogeographical studies.
