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Fritz Schlunegger - One of the best experts on this subject based on the ideXlab platform.
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Tectonic processes, variations in sediment flux, and eustatic sea level recorded by the 20 Myr old Burdigalian transgression in the Swiss Molasse basin
Solid Earth, 2019Co-Authors: Philippos Garefalakis, Fritz SchluneggerAbstract:Abstract. The stratigraphic architecture of the Swiss Molasse basin, situated on the northern side of the evolving Alps, reveals crucial information about the basin's geometry, its evolution, and the processes leading to the deposition of the siliciclastic sediments. Nevertheless, the formation of the Upper Marine Molasse (OMM) and the controls on the related Burdigalian transgression have still been a matter of scientific debate. During the time period from ca. 20 to 17 Ma, the Swiss Molasse basin was partly flooded by a shallow marine sea striking SW–NE. Previous studies have proposed that the transgression occurred in response to a rise in global sea level, a reduction of sediment flux, or an increase in tectonically controlled accommodation space. Here, we readdress this problem and extract stratigraphic signals from the Burdigalian Molasse deposits that can be related to changes in sediment supply rate, variations in the eustatic sea level, and subduction tectonics. To achieve this goal, we conducted sedimentological and stratigraphic analyses of several sites across the entire Swiss Molasse basin. Field investigations show that the transgression and the subsequent evolution of the Burdigalian seaway was characterized by (i) a deepening and widening of the basin, (ii) phases of erosion and non-deposition during Lower Freshwater Molasse (USM), OMM, and Upper Freshwater Molasse (OSM) times, and (iii) changes in along-strike drainage reversals. We use these changes in the stratigraphic record to disentangle tectonic and surface controls on the facies evolution at various scales. As the most important mechanism, rollback subduction of the European mantle lithosphere most likely caused a further downwarping of the foreland plate, which we use to explain the deepening and widening of the Molasse basin, particularly at distal sites. In addition, subduction tectonics also caused the uplift of the Aar massif. This process was likely to have shifted the patterns of surface loads, thereby resulting in a buckling of the foreland plate and influencing the water depths in the basin. We use this mechanism to explain the establishment of distinct depositional settings, particularly the formation of subtidal shoals wherein a bulge in relation to this buckling is expected. The rise of the Aar massif also resulted in a reorganization of the drainage network in the Alpine hinterland, with the consequence that the sediment flux to the basin decreased. We consider this reduction in sediment supply to have amplified the tectonically controlled deepening of the Molasse basin. Because the marine conditions were generally very shallow, subtle changes in eustatic sea level contributed to the formation of several hiatuses that chronicle periods of erosion and non-sedimentation. These processes also amplified the tectonically induced increase in accommodation space during times of global sea level highstands. Whereas these mechanisms are capable of explaining the establishment of the Burdigalian seaway and the formation of distinct sedimentological niches in the Swiss Molasse basin, the drainage reversal during OMM times possibly requires a change in tectonic processes at the slab scale, most likely including the entire Alpine range between the Eastern and Central Alps. In conclusion, we consider rollback tectonics to be the main driving force controlling the transgression of the OMM in Switzerland, with contributions by the uplift of individual crustal blocks (here the Aar massif) and by a reduction of sediment supply. This reduction of sediment flux was likely to have been controlled by tectonic processes as well when basement blocks became uplifted, thereby modifying the catchment geometries. Eustatic changes in sea level explain the various hiatuses and amplified the deepening of the basin during eustatic highstand conditions.
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Deciphering tectonic, eustatic and surface controls on the 20 Ma-old Burdigalian transgression recorded in the Upper Marine Molasse in Switzerland
2019Co-Authors: Philippos Garefalakis, Fritz SchluneggerAbstract:Abstract. The stratigraphic architecture of the Swiss Molasse basin reveals crucial information about the basin’s geometry, its evolution and the processes leading to the deposition of the clastic material. Nevertheless, the formation of the Upper Marine Molasse (OMM) and the controls on the related Burdigalian transgression are not fully understood yet. During these times, from c. 20 to 17 Ma, the Swiss Molasse basin was partly flooded by a peripheral shallow marine sea, striking SW – NE. We proceeded through detailed sedimentological and stratigraphic examinations of several sites across the entire Swiss Molasse basin in order to deconvolve the stratigraphic signals related surface and tectonic controls. Surface-related signals include stratigraphic responses to changes in eustatic sea level and sediment fluxes, while the focus on crustal-scale processes lies on the uplift of the Aar-massif at c. 20 Ma. Field examinations show, that the evolution of the Burdigalian seaway was characterized by (i) shifts in the depositional settings, (ii) changes in discharge directions, a deepening and widening of the basin, and (iv) phases of erosion and non-deposition. We relate these changes in the stratigraphic records to a combination of surface and tectonic controls at various scales. In particular, roll-back subduction of the European mantle lithosphere, delamination of crustal material and the associated rise of the Aar-massif most likely explain the widening of the basin particular at distal sites. In addition, the uplift of the Aar-massif was likely to have shifted the patterns of surface loads. These mechanisms could have caused a flexural adjustment of the foreland plate underneath the Molasse basin, which we use as mechanism to explain the establishment of distinct depositional environments and particularly the formation of subtidal-shoals where a lateral bulge is expected. In the Alpine hinterland, these processes occurred simultaneously with a period of fast tectonic exhumation accomplished through slip along the Simplon detachment fault, with the consequence that sediment flux to the basin decreased. It is possible that this reduction in sediment supply contributed to the establishment of marine conditions in the Swiss Molasse basin and thus amplified the effect related to the tectonically controlled widening of the basin. Because of the formation of shallow marine conditions, subtle changes in the eustatic sea level contributed to the occurrence several hiatus that chronicle periods of erosion and non-sedimentation. While these mechanisms are capable of explaining the establishment of the Burdigalian seaway and the formation of distinct sedimentological niches in the Swiss Molasse basin, the drainage reversal during OMM-times possibly requires a change in the tectonic processes at the slab scale. We conclude that sedimentological records can be used to decipher surface controls and lithospheric-scale processes in orogens from the stratigraphic record, provided that a detailed sedimentological and chronological database is available.
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The last erosional stage of the Molasse Basin and the Alps
International Journal of Earth Sciences, 2010Co-Authors: Fritz Schlunegger, Jon MosarAbstract:We present a synoptic overview of the Miocene-present development of the northern Alpine foreland basin (Molasse Basin), with special attention to the pattern of surface erosion and sediment discharge in the Alps. Erosion of the Molasse Basin started at the same time that the rivers originating in the Central Alps were deflected toward the Bresse Graben, which formed part of the European Cenozoic rift system. This change in the drainage direction decreased the distance to the marine base level by approximately 1,000 km, which in turn decreased the average topographic elevation in the Molasse Basin by at least 200 m. Isostatic adjustment to erosional unloading required ca. 1,000 m of erosion to account for this inferred topographic lowering. A further inference is that the resulting increase in the sediment discharge at the Miocene–Pliocene boundary reflects the recycling of Molasse units. We consider that erosion of the Molasse Basin occurred in response to a shift in the drainage direction rather than because of a change in paleoclimate. Climate left an imprint on the Alpine landscape, but presumably not before the beginning of glaciation at the Pliocene–Pleistocene boundary. Similar to the northern Alpine foreland, we do not see a strong climatic fingerprint on the pattern or rates of exhumation of the External Massifs. In particular, the initiation and acceleration of imbrication and antiformal stacking of the foreland crust can be considered solely as a response to the convergence of Adria and Europe, irrespective of erosion rates. However, the recycling of the Molasse deposits since 5 Ma and the associated reduction of the loads in the foreland could have activated basement thrusts beneath the Molasse Basin in order to restore a critical wedge. In conclusion, we see the need for a more careful consideration of both tectonic and climatic forcing on the development of the Alps and the adjacent Molasse Basin.
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Sedimentary Sequences, Seismic Facies, Subsidence Analysis, and Evolution of the Burdigalian Upper Marine Molasse Group, Central Switzerland
AAPG Bulletin, 1997Co-Authors: Fritz Schlunegger, Werner Leu, Albert MatterAbstract:The sedimentological interpretation of seismic and borehole data derived from the Burdigalian Upper Marine Molasse Group of the central North Alpine foreland basin enables a detailed reconstruction of the shallow-marine architecture. The different seismic facies are assigned to the shoreface/foreshore, nearshore, and offshore depositional systems. Mapping of the seismic facies on the seismic line reveals the presence of two prograding sequences (Luzern and St. Gallen formations) that are separated by an unconformity. The subsidence analysis suggests that the evolution of the Upper Marine Molasse was primarily controlled by the interaction between tectonic subsidence and sediment supply. The distal transgressions of the Luzern and St. Gallen formations and the establishment of shallow-marine environments were caused by enhanced subsidence rates in the distal reaches associated with increased sediment supply rates. The development of the sequence boundaries separating the Luzern and St. Gallen formations and the regression at the end of the St. Gallen Formation, however, were controlled by uplift in the distal part of the basin. The subsidence and sediment flux analyses of the Upper Marine Molasse allow an improved understanding of the tectonic and denudation history of the northern Alps. Out-of-sequence thickening in the rear of the northern Alps by underplating of the Aar massif and forward thrusting of the Helvetic nappes is interpreted to have controlled uplift in the distal part of the basin and the formation of the sequence boundaries. In-sequence crustal thickening at the tip of the orogenic wedge by forward underthrusting of Lower Freshwater Molasse thrust sheets beneath Molasse deposits associated with enhanced erosion of the northern Alps caused a northward shift of the location of the major orogenic load and an increase of the sediment supply to the Molasse basin. These processes are interpreted to have controlled the distal shifts of the basin depocenter and the distal transgressions of the Luzern and St. Gallen formations.
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Alluvial fan sedimentation and structure of the southern Molasse Basin margin, Lake Thun area, Switzerland
Eclogae Geologicae Helvetiae, 1994Co-Authors: Fritz Schlunegger, Albert Matter, MangeAbstract:The Chattian Lower Freshwater Molasse (USM) of the Thun area comprises a thick series of continental sediments which occur in three imbricate thrust sheets (Steffisburg, Zulg-Hombach, Blueme) of the Subalpine Molasse and over wide areas of the autochthonous Plateau Molasse. Facies analysis of outcrops, complemented by conglomerate clast counts, sandstone petrography, heavy mineral analysis and data from two deep exploration wells and seismics permit structural restoration of the thrust sheets, correlation of subalpine and autochthonous USM and consequently the reconstruction of the geometry and facies evolution of the alluvial fan systems. The most complete succession measuring more than 4500 m is preserved in the structurally highest Blueme thrust sheet
Harald Stollhofen - One of the best experts on this subject based on the ideXlab platform.
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a normal faulting stress regime in the bavarian foreland Molasse basin new evidence from detailed analysis of leak off and formation integrity tests in the greater munich area se germany
Tectonophysics, 2019Co-Authors: M. Drews, Robin Seithel, Alexandros Savvatis, Thomas Kohl, Harald StollhofenAbstract:Abstract Leak-off and formation integrity test data from the central part of the Bavarian Foreland Molasse Basin have been investigated in detail to infer information about the stress regime of the Cenozoic basin fill. The detailed analysis of leak-off test data from the Bavarian Foreland Molasse Basin and lithology-dependent analysis of leak-off test and formation integrity data is the first of its kind in a published study. Only test data from shale-rich sequences have been considered. All data yield minimum principal stresses that are smaller than an estimated vertical stress range. In combination with critical stress and frictional equilibrium theory, the data indicate that the stress regime in the greater Munich area and possibly the far-field stress regime of the Bavarian Foreland Molasse Basin are most likely of an extensional nature (normal-faulting stress regime). Under the assumption of frictional equilibrium, a friction coefficient between 0.2 and 0.4 best explains failure in shale-dominated sections of the central part of the Bavarian Foreland Molasse Basin and can be used to estimate the minimum horizontal stress SHmin. However, even in the spatially restricted domain of the greater Munich area the stress regime might vary towards a strike-slip stress regime; most likely in the vicinity of fault zones and/or due to variations in mechanical rock strength. The results of this study have great impact and relevance to improved planning of drilling campaigns, future numerical modelling and the general understanding of the evolution of the Bavarian Foreland Molasse Basin. Additional leak-off tests and extended leak-off tests are recommended to fully unravel the spatial variation and geologic control factors of the stress regime of the entire Bavarian Foreland Molasse Basin.
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Disequilibrium compaction overpressure in shales of the Bavarian Foreland Molasse Basin: Results and geographical distribution from velocity-based analyses
Marine and Petroleum Geology, 2018Co-Authors: M. Drews, Wolfgang Bauer, Luca Caracciolo, Harald StollhofenAbstract:Abstract Shale velocity data from sonic logs and vertical seismic profiles, drilling data and in situ pressure measurements from a total of 116 wells have been analyzed to gain an improved understanding of the lateral and vertical distribution and formation of overpressure in the Bavarian Foreland Molasse Basin. Pore pressure from sonic and vertical seismic profile velocities has been analyzed by establishing a normal compaction trend for Cenozoic and Mesozoic shales combined with a classical Eaton approach. The study demonstrates that a single shale normal compaction trend for the Bavarian Foreland Molasse Basin is sufficient to estimate pore pressure and thus overpressure from sonic and vertical seismic profile velocity. Maximum overpressure develops at depths between 1500 and 2500 m and increases with depth at a constant effective stress of 20 MPa. The strong dependency of overpressure on burial depth, constant effective stress and restriction to shale units that are overlain by sequences with very high sedimentation rates indicates that disequilibrium compaction is the main cause for overpressure. Also, variable presence of Cretaceous shales is a key control of overpressure occurrence in Oligocene shales in the Bavarian Foreland Molasse Basin, since Cretaceous shales likely act as a “pressure buffer” to underpressured Mesozoic carbonates. Successful detection and prediction of overpressure from vertical seismic profile data is encouraging for future pre-drill prediction of overpressure from velocity data of seismic surveys in the Bavarian Foreland Molasse Basin, resulting in improved well planning, reliable calculation of project costs, and improved safety during drilling activities in the Bavarian Foreland Molasse Basin. The presented overpressure distributions will be a key input for future geomechanical, basin and reservoir modelling studies in the Bavarian Foreland Molasse Basin.
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Reentering of an Overpressured Basin - The South German Molasse
First EAGE Workshop on Pore Pressure Prediction, 2017Co-Authors: M. Drews, Wolfgang Bauer, Harald StollhofenAbstract:The German Molasse Basin is part of the greater Northern Alpine Foreland basin and has been extensively explored and exploited by the hydrocarbon industry in the 1950s-1970s. Today, the Molasse Basin area is a main target for deep hydrothermal energy exploration and production in Germany. Although the sediments of the Molasse Basin are increasingly overpressured towards the Alps and despite continuous drilling events in the overpressured parts of the Molasse Basin, an analytical, predictive model that can be used for predrill pore pressure prediction based on offset well data and local geology is not existent, yet. Instead, the current understanding is mainly based on the regional distribution of maximum drilling mud weights and offset drilling events and postulates a combination of high sedimentation rates and Alpine tectonic stress. In this study, we aim to systematically investigate the compaction behavior of the overpressured shales throughout the basin as well as the contribution of tectonic stress, local lateral pressure transfer and other effects on overpressure generation. The ultimate goal is to develop a reliable pore pressure prediction model for future well planning in the German Molasse Basin. We would like to introduce the project and show examples and first results.
Albert Matter - One of the best experts on this subject based on the ideXlab platform.
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Depositional and structural evolution of a foreland basin margin in a magnetostratigraphic framework: the eastern Swiss Molasse Basin
International Journal of Earth Sciences, 1999Co-Authors: Oliver Kempf, Albert Matter, Douglas W. Burbank, M. MangeAbstract:This integrated study of the sedimentology, magnetostratigraphic chronology and petrography of the mostly continental clastics of the Oligocene to Miocene Swiss Molasse Basin underpins a reconstruction of facies architecture and delineates relationships between the depositional evolution of a foreland-basin margin and exhumation phases and orogenic events in the adjacent orogen. A biostratigraphically based high-resolution magnetostratigraphy provides a detailed temporal framework and covers nearly the whole stratigraphic record of the Molasse Basin (31.5–13 Ma). Three transverse alluvial fan systems evolved at the southern basin margin. They are characterized by distinct petrographic compositions and document the exhumation and denudation history of the growing eastern Swiss Alps. Enhanced northward propagation of the orogenic wedge is interpreted to have occurred between 31.5 and 26 Ma. During the period 24–19 Ma, intense in-sequence and out-of-sequence thrusting took place as Molasse strata were accreted to the orogenic wedge. A third active tectonic phase, possibly caused by backthrusting of the Plateau Molasse, probably occurred between ca. 15 and 13 Ma. Fan head migration between 31.5 and 13 Ma is probably controlled by the structural evolution of the thrust front due to Molasse accretion and backthrusting.
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Sedimentary Sequences, Seismic Facies, Subsidence Analysis, and Evolution of the Burdigalian Upper Marine Molasse Group, Central Switzerland
AAPG Bulletin, 1997Co-Authors: Fritz Schlunegger, Werner Leu, Albert MatterAbstract:The sedimentological interpretation of seismic and borehole data derived from the Burdigalian Upper Marine Molasse Group of the central North Alpine foreland basin enables a detailed reconstruction of the shallow-marine architecture. The different seismic facies are assigned to the shoreface/foreshore, nearshore, and offshore depositional systems. Mapping of the seismic facies on the seismic line reveals the presence of two prograding sequences (Luzern and St. Gallen formations) that are separated by an unconformity. The subsidence analysis suggests that the evolution of the Upper Marine Molasse was primarily controlled by the interaction between tectonic subsidence and sediment supply. The distal transgressions of the Luzern and St. Gallen formations and the establishment of shallow-marine environments were caused by enhanced subsidence rates in the distal reaches associated with increased sediment supply rates. The development of the sequence boundaries separating the Luzern and St. Gallen formations and the regression at the end of the St. Gallen Formation, however, were controlled by uplift in the distal part of the basin. The subsidence and sediment flux analyses of the Upper Marine Molasse allow an improved understanding of the tectonic and denudation history of the northern Alps. Out-of-sequence thickening in the rear of the northern Alps by underplating of the Aar massif and forward thrusting of the Helvetic nappes is interpreted to have controlled uplift in the distal part of the basin and the formation of the sequence boundaries. In-sequence crustal thickening at the tip of the orogenic wedge by forward underthrusting of Lower Freshwater Molasse thrust sheets beneath Molasse deposits associated with enhanced erosion of the northern Alps caused a northward shift of the location of the major orogenic load and an increase of the sediment supply to the Molasse basin. These processes are interpreted to have controlled the distal shifts of the basin depocenter and the distal transgressions of the Luzern and St. Gallen formations.
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Alluvial fan sedimentation and structure of the southern Molasse Basin margin, Lake Thun area, Switzerland
Eclogae Geologicae Helvetiae, 1994Co-Authors: Fritz Schlunegger, Albert Matter, MangeAbstract:The Chattian Lower Freshwater Molasse (USM) of the Thun area comprises a thick series of continental sediments which occur in three imbricate thrust sheets (Steffisburg, Zulg-Hombach, Blueme) of the Subalpine Molasse and over wide areas of the autochthonous Plateau Molasse. Facies analysis of outcrops, complemented by conglomerate clast counts, sandstone petrography, heavy mineral analysis and data from two deep exploration wells and seismics permit structural restoration of the thrust sheets, correlation of subalpine and autochthonous USM and consequently the reconstruction of the geometry and facies evolution of the alluvial fan systems. The most complete succession measuring more than 4500 m is preserved in the structurally highest Blueme thrust sheet
Bettina Reichenbacher - One of the best experts on this subject based on the ideXlab platform.
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Early Miocene continental gastropods from new localities of the Molasse Basin in southern Germany
PalZ, 2016Co-Authors: Rodrigo B. Salvador, Martina Pippèrr, Bettina Reichenbacher, Michael W. RasserAbstract:Here, we present the continental aquatic and terrestrial gastropods found in samples of 11 new boreholes in the Molasse Basin, southern Germany. The samples come from the Lower Freshwater Molasse (USM), the Upper Brackish Molasse (OBM; Grimmelfingen and Kirchberg Formations) and the Upper Freshwater Molasse (OSM). The studied segments of these lithostratigraphical units represent the beginning of the lower Miocene (USM), and the uppermost lower Miocene (OBM, OSM). Twenty-four species of terrestrial and freshwater gastropods are reported here, belonging to the families Neritidae, Melanopsidae, Pachychilidae, Bithyniidae, Hydrobiidae, Truncatellidae(?), Viviparidae, Valvatidae(?), Lymnaeidae, Planorbidae, Carychiidae, Zonitidae, Helicidae, Hygromiidae and Discidae(?). We provide remarks on the taxonomy of some of the studied species, including a revision of Theodoxus cyrtocelis, T. obstusangula and T. sparsus (the latter can be considered a synonym of T. cyrtocelis). Finally, we present a paleoecological interpretation for the USM, OBM and OSM based on the gastropod fauna.
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Tidal sediments in the Upper Marine Molasse (OMM) of the Allgäu area (Lower Miocene, Southwest-Germany)
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2009Co-Authors: Dorothea Frieling, Rajat Mazumder, Bettina ReichenbacherAbstract:, B. (2009): Tidal sediments in the Upper MarineMolasse (OMM) of the Allgau area (Lower Miocene, Southwest-Germany). N. Jb. Geol. Palaont.Abh., 254 : 151163; Stuttgart.Abstract: Evidence for tidal influences in the Upper Marine Molasse (OMM) of the Allgau area(Southwest German part of the Molasse Basin) is presented. The studied sections in the EllhoferTobel ravine reveal an approximately 140 m thick succession of marine sediments. Four differentfacies types are distinguished in this succession: 1) a Glauconitic Sandstone Facies, 2) a HeterolithicFacies, 3) a Cross-Stratified Sandstone Facies and 4) a Conglomeratic Facies. These lithofaciesrepresent different near coastal and shallow marine environments. A tidal influence is indicated bythe presence of the Heterolithic Facies which contains associated epsilon cross-stratification andmegaripples (or subaquatic dunes). A general current direction from south to north is consistentdocumented by subaquatic dune foresets and the orientation of ripple foresets. If the coastalenvironment near the southern coast of the Molasse Sea had a rather simple tidal current regime thisdominant northerly current direction could be interpreted as ebb currents. Keywords: Early Miocene, Molasse Basin, Allgau, Upper Marine Molasse (OMM), tidal sediments.
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A fourth St. Gallen Formation cycle (?) in the Karpatian Upper Marine Molasse of central Switzerland
Facies, 2005Co-Authors: Bettina Reichenbacher, Daniel Kälin, Jürg JostAbstract:The Mauensee section in the Molasse Basin (North Alpine Foreland Basin) of central Switzerland represents one of the best continuously exposed outcrops of the St. Gallen Formation of the Upper Marine Molasse. A similarly well-exposed section is at Schmiedrued, situated about 15 km to the north. Biostratigraphic analysis of mammal and fish faunas shows that both sections are of Early Karpatian age. Palaeoecological analysis of the biota indicates an oligohaline intercalation within the marine part of the sections. This is additionally confirmed by the oxygen isotopic compositions of fish otoliths from the Mauensee section. The overlying marine sequence may represent a fourth cycle in the St. Gallen Formation that might perhaps indicate a Karpatian transgression from the Mediterranean Sea, which has not previously been recognized. Biostratigraphic comparison shows that the sedimentation of the Upper Freshwater Molasse began at the base of the Karpatian in southwest Germany and eastern Switzerland, and in the Middle Karpatian in central Switzerland. The presence of a Karpatian marine sedimentation area in central Switzerland may explain that the terrestrial sedimentation of the Upper Freshwater Molasse began at such different times.
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a fourth st gallen formation cycle in the karpatian upper marine Molasse of central switzerland
Facies, 2005Co-Authors: Bettina Reichenbacher, Daniel Kälin, Jürg JostAbstract:The Mauensee section in the Molasse Basin (North Alpine Foreland Basin) of central Switzerland represents one of the best continuously exposed outcrops of the St. Gallen Formation of the Upper Marine Molasse. A similarly well-exposed section is at Schmiedrued, situated about 15 km to the north. Biostratigraphic analysis of mammal and fish faunas shows that both sections are of Early Karpatian age. Palaeoecological analysis of the biota indicates an oligohaline intercalation within the marine part of the sections. This is additionally confirmed by the oxygen isotopic compositions of fish otoliths from the Mauensee section. The overlying marine sequence may represent a fourth cycle in the St. Gallen Formation that might perhaps indicate a Karpatian transgression from the Mediterranean Sea, which has not previously been recognized. Biostratigraphic comparison shows that the sedimentation of the Upper Freshwater Molasse began at the base of the Karpatian in southwest Germany and eastern Switzerland, and in the Middle Karpatian in central Switzerland. The presence of a Karpatian marine sedimentation area in central Switzerland may explain that the terrestrial sedimentation of the Upper Freshwater Molasse began at such different times.
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Biota, palaeoenvironments and biostratigraphy of continental Oligocene deposits of the South German Molasse Basin (Penzberg Syncline)
Palaeontology, 2004Co-Authors: Bettina Reichenbacher, Undine Uhlig, Thorsten Kowalke, Barbara Bassler, Renate Matzke-karasz, Bettina SchenkAbstract:Six charophyte, 13 mollusc, four ostracod and nine fish otolith taxa are taxonomically described, and one fruit, one seed and two foraminiferal taxa are briefly noted from the Lower Cyrena Beds and the Lower Coloured Molasse of the Sindelsdorf section near Penzberg (approximately 50 km south of Munich). Our palaeoecological and lithological data from the Lower Cyrena Beds suggest a delta plain with lagoons, estuaries, slowly flowing rivers, lakes and swamps. Faunal and floral elements of the Lower Coloured Molasse indicate lacustrine environments. The gastropod Tympanotonos and the tropical to subtropical fish fauna (Eleotridae, Ambassidae and Cyprinodontidae) suggest a warm, at least subtropical climate. Furthermore, Tympanotonos suggests comparisons with Recent molluscan faunas of the mangrove swamps of the West African coast, and thus hints at mangrove vegetation bordering the coasts of the Upper Bavarian Molasse Sea. A biostratigraphical classification for the Oligocene Molasse deposits of the Penzberg Syncline is established for the first time based on otoliths and charophytes. The Lower Cyrena Beds are attributed to the newly defined otolith zone OT-O1/2 and probably correspond to the oldest part of the Chara microcera Zone. The lowermost part of the Lower Coloured Molasse can be correlated both with otolith zone OT-O2 and the Chara microcera Zone. The Sindelsdorf section lies within the Rupelian–Chattian transition zone and thus the chronostratigraphic age is approximately 29–28 Ma.
Michael Schneider - One of the best experts on this subject based on the ideXlab platform.
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The origin of deep geothermal anomalies in the German Molasse Basin: results from 3D numerical models of coupled fluid flow and heat transport
Geothermal Energy, 2017Co-Authors: Anna M. Przybycin, Magdalena Scheck-wenderoth, Michael SchneiderAbstract:The European Molasse Basin is a Tertiary foreland basin at the northern front of the Alps, which is filled with mostly clastic sediments. These Molasse sediments are underlain by Mesozoic sedimentary successions, including the Upper Jurassic aquifer ( Malm) which has been used for geothermal energy production since decades. The thermal field of the Molasse Basin area is characterized by prominent thermal anomalies. Since the origin of these anomalies is still an object of debates, especially the negative ones represent a high risk for geothermal energy exploration. With our study, we want to contribute to the understanding of the thermal configuration of the basin area and with that help to reduce the exploration risk for future geothermal projects in the Molasse Basin. For this, we conducted 3D basin-scale coupled fluid and heat transport simulations to reproduce the present-day thermal field of the Molasse Basin by considering conduction, advection, and convection as heat-driving mechanisms. Within this paper, we show how the temperature distribution of the Molasse Basin, including the pronounced thermal anomalies, can be reproduced by coupled fluid flow and heat transport simulations following a multi-scale 3D-modelling approach. We find that the shallow thermal field is strongly affected by basin-wide fluid flow. Furthermore, we show that the temperature distribution at the depth of the Malm aquifer is strongly influenced by the hydraulic conductivity of the Foreland and Folded Molasse Sediments and that hydraulically conductive faults have only a minor influence on the regional temperature distribution. Moreover, we show that the positive and negative thermal anomalies are caused by the superposed effects of conductive and advective heat transport and correlated with the geological structure.
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The origin of deep geothermal anomalies in the German Molasse Basin: results from 3D numerical models of coupled fluid flow and heat transport
Geothermal Energy, 2017Co-Authors: Anna M. Przybycin, Magdalena Scheck-wenderoth, Michael SchneiderAbstract:The European Molasse Basin is a Tertiary foreland basin at the northern front of the Alps, which is filled with mostly clastic sediments. These Molasse sediments are underlain by Mesozoic sedimentary successions, including the Upper Jurassic aquifer ( Malm) which has been used for geothermal energy production since decades. The thermal field of the Molasse Basin area is characterized by prominent thermal anomalies. Since the origin of these anomalies is still an object of debates, especially the negative ones represent a high risk for geothermal energy exploration. With our study, we want to contribute to the understanding of the thermal configuration of the basin area and with that help to reduce the exploration risk for future geothermal projects in the Molasse Basin. For this, we conducted 3D basin-scale coupled fluid and heat transport simulations to reproduce the present-day thermal field of the Molasse Basin by considering conduction, advection, and convection as heat-driving mechanisms. Within this paper, we show how the temperature distribution of the Molasse Basin, including the pronounced thermal anomalies, can be reproduced by coupled fluid flow and heat transport simulations following a multi-scale 3D-modelling approach. We find that the shallow thermal field is strongly affected by basin-wide fluid flow. Furthermore, we show that the temperature distribution at the depth of the Malm aquifer is strongly influenced by the hydraulic conductivity of the Foreland and Folded Molasse Sediments and that hydraulically conductive faults have only a minor influence on the regional temperature distribution. Moreover, we show that the positive and negative thermal anomalies are caused by the superposed effects of conductive and advective heat transport and correlated with the geological structure.