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a Darcy's velocity magnitude at present (time = 1.3E5 a) for the high Malm permeability scenario with a constant surface temperature (i.e. model run B), and b difference of Darcy's velocity magnitude between the high and low Malm permeability scenarios (i.e. difference between model runs B and A). Darcy's velocity magnitude is expressed as logarithm base 10 and unit m a −1 . Vertical exaggeration equals three
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The Molasse Basin in Southern Germany is part of the North Alpine Foreland Basin and hosts the largest accumulation of deep geothermal production fields in Central Europe. Despite the vast development of geothermal energy utilization projects especially in the Munich metropolitan region, the evolution of and control factors on the natural geotherma...
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... velocity magnitude is a measure of how fast groundwater is flowing. We show Darcy's velocity magnitude resulting from model run B as a primary characteristic of the k structure and groundwater flow in the high Malm k scenario (Fig. 8a). In order to compare Darcy's velocity magnitude in both k scenarios and to show the related model sensitivity, Fig. 8b shows the difference of Darcy's velocity magnitude between model runs B and A (Fig. 3). In agreement with the very low k, groundwater flow is extremely slow in the Variscan basement. A contrast of up to three orders of ...
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... velocity magnitude is a measure of how fast groundwater is flowing. We show Darcy's velocity magnitude resulting from model run B as a primary characteristic of the k structure and groundwater flow in the high Malm k scenario (Fig. 8a). In order to compare Darcy's velocity magnitude in both k scenarios and to show the related model sensitivity, Fig. 8b shows the difference of Darcy's velocity magnitude between model runs B and A (Fig. 3). In agreement with the very low k, groundwater flow is extremely slow in the Variscan basement. A contrast of up to three orders of magnitude exists between Darcy's velocity magnitude in the Malm aquifer and in the Molasse. In both the low and high ...
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... velocity magnitude within the Malm aquifer is lower than 0.1 m a −1 in the deepest part of the MB, whereas it progressively increases to about 1 m a −1 in the centre of the MB (section km 65) and further increases to about 10 m a −1 near the Danube. Darcy's velocity magnitude within the Molasse ranges between about 0.01 m a −1 and 0.1 m a −1 (Fig. 8a). In the Franconian Alb to the north of the Danube where the karstified Malm carbonate is exposed, our models show that Darcy's velocity magnitude exceeds 10 m a −1 with a maximum of more than 1000 m a −1 . As shown in Fig. 8b, the higher Malm k causes a significantly higher Darcy's velocity magnitude within the Molasse and in the ...
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... 10 m a −1 near the Danube. Darcy's velocity magnitude within the Molasse ranges between about 0.01 m a −1 and 0.1 m a −1 (Fig. 8a). In the Franconian Alb to the north of the Danube where the karstified Malm carbonate is exposed, our models show that Darcy's velocity magnitude exceeds 10 m a −1 with a maximum of more than 1000 m a −1 . As shown in Fig. 8b, the higher Malm k causes a significantly higher Darcy's velocity magnitude within the Molasse and in the direction of the Danube, especially in the northern two-thirds of the MB. The higher Malm k also significantly affects the groundwater regime within the MB by causing an increase and a decrease of Darcy's velocity magnitude in the ...
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... higher Darcy's velocity magnitude within the Molasse and in the direction of the Danube, especially in the northern two-thirds of the MB. The higher Malm k also significantly affects the groundwater regime within the MB by causing an increase and a decrease of Darcy's velocity magnitude in the deeper and shallower parts, respectively (Fig. 8b). Figure 9 shows the Péclet number distribution for the low and high Malm k scenarios, respectively, with a constant T S condition, as the respective results of model runs A and B (Fig. 3). In both model scenarios, heat conduction characterizes the Variscan basement, which is in agreement with the cataloguing of the MB as ...
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... model results confirm the main findings of thermal-hydraulic modelling performed by Przybycin et al. (2017). The Malm and the Tertiary sediment fill of the MB present a sufficiently high formation k for basin-wide gravity-driven fluid flow and convective heat flow. Since the range of Darcy's velocity magnitude is mostly between 0.01 and 1 m a −1 (Fig. 8), and thus relatively low, Darcy's law remains valid. Przybycin et al. (2017) suggest that heterogeneities in thermal conductivity contribute fundamentally to the generation of pronounced positive and negative thermal anomalies in the MB. We put forward high formation k and pervading gravity-driven groundwater flow as key factors for ...
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The perforated Pediastrum Meyen s.l. species are recorded for the first time in the basal levels of the Tithonian Vaca Muerta Formation, extending its first stratigraphical record to ages as old as Late Jurassic times. Based on the ecological requirements of Pediastrum simplex var. clathratum and P. simplex var. biwaense, the previously warm paleoc...
Citations
... The Franconian Basin deposition spans from Permian (Rotliegend) to Cretaceous and is formed of sandstones, siltstones, mudstones and limestones (Schröder, 1987;Schäfer et al. 2000, Freudenberger et al. 2013Kämmlein et al. 2017). The outcrops of interest lie within the Malm (Upper Jurassic) limestone unit deposited as an extensive carbonate-dominated platform (Franconian Platform) along the passive Tethyian margin (Meyer & Schmidt-Kaler, 1990;Ziegler 1990;Schintgen & Moeck, 2021). ...
... Recent studies have primarily focused on characterizing and modelling the deep geothermal potential of the granite systems; however, little research has been undertaken to explore the fractured sedimentary cover and the influence of the fracture networks on geothermal flow (Kämmlein et al. 2017;de Wall et al. 2019;Bohnsack et al. 2020). In the Molasse Basin ( Fig. 1) to the south, the Malm unit is currently utilized for geothermal energy where structural features (fractures, faults and karst) play a key role in producing high flow rates up to 10 −4 m s −1 to the north of the basin (Birner et al. 2012;Birner, 2013;Przybycin et al. 2017;Bohnsack et al. 2020;Schintgen & Moeck, 2021). It is therefore important that geothermal flow through fractured networks of the Franconian Basin be better understood for future exploration. ...
... Therefore, the fault directly influences the orientation of the permeability tensors and ellipses and thus fluid flow. Fluid flow orientation is important within the reservoir, particularly when primary permeability is controlled by structural features rather than sedimentological properties as observed within the Malm (Birner et al. 2012;Schintgen and Moeck 2021). ...
Faulted and fractured systems form a critical component of fluid flow, especially within low-permeable reservoirs. Therefore, developing suitable methodologies for acquiring structural data and simulating flow through fractured media is vital to improve efficiency and reduce uncertainties in modelling the subsurface. Outcrop analogues provide excellent areas for the analysis and characterization of fractures within the reservoir rocks where subsurface data are limited. Variation in fracture arrangement, distribution and connectivity can be obtained from 2D fractured cliff sections and pavements. These sections can then be used for efficient discretization and homogenization techniques to obtain reliable predictions on permeability distributions in the geothermal reservoirs. Fracture network anisotropy in the Malm reservoir unit is assessed using detailed structural analysis and numerical homogenization of outcrop analogues from an open pit quarry within the Franconian Basin, Germany. Several events are recorded in the fracture networks from the Late Jurassic the Alpine Orogeny and are observed to be influenced by the Kulmbach Fault nearby with a reverse throw of 800 m. The fractured outcrops are digitized for fluid flow simulations and homogenization to determine the permeability tensors of the networks. The tensors show differences in fluid transport direction where fracture permeability is controlled by orientation compared to a constant value. As a result, it is observed that the orientation of the tensor is influenced by the Kulmbach Fault, and therefore faults within the reservoirs at depth should be considered as important controls on the fracture flow of the geothermal system.
