The regions of South Moravia in Czech Republic and Lower Austria are well-known for their use of thermal mineral waters for balneological purposes. Mineral waters are exploited from a Jurassic aquifer by two about 1.5 km deep wells MUS-3G (Pasohlavky, Czech Republic) and Laa TH Nord 1 (Laa an der Thaya, Austria). This Jurassic aquifer buried below the Neogene foredeep overlies a crystalline basement of Bohemian Massif and continues to the southeast below the Western Carpathians. Jurassic sediments which are mainly composed of autochthonous carbonates increase their thickness in this direction due to the decline of the crystalline basement. Because of this decline, there are two developments of Jurassic sediments, the shallower on the northwest and the deeper on the southeast. The zone between these two developments is known as the Mušov transition zone. For sustainable mineral water resources development, a groundwater flow pattern and recharge are evaluated. This evaluation includes both the hydrogeologic structure of Jurassic carbonates and hydraulically continuous underlying and overlying rocks. Because of the considerable depth of this hydrogeologic structure, which ranges from 100 to 3 000 metres below sea level, this study was based mostly on archive reports related to deep wells at the study area. The extent of studied units was identified on well-log data and geophysical survey interpretation. The resulting groundwater level contour map is based on the spatial distribution of hydraulic heads ranging approx. from 180 to 220 metres above sea level (masl) that were derived from pressure and water density conditions at the Jurassic aquifer. The general direction of groundwater flow is from northwest and southeast to the drainage zone (hydraulic head approx. 170–190 masl) identified in the middle of the studied area, which is identical to a course of the Mušov transition zone and parallel to the course of Dyje river (water table 170–180 masl). The northwestern part of the studied hydrogeological structure also differs from the southeastern part in a lower total mineralization which indicates active inflow of fresh water. The study was also enhanced by a spatial distribution of hydraulic parameters of all modelled units. These parameters were derived from hydrodynamic tests. The hydraulic conductivity values for the major Jurassic aquifer range from 6.0 × 10-4 to 1.3 × 10-9 m/s. The occurrence of the higher hydraulic conductivity near the drainage zone indicates the presence of a well-developed drainage network.
The Jurassic sedimentary succession along the eastern margin of the Bohemian Massif starts with mostly fluvial deposits of the Gresten Formation and continues after marine transgression with the deposition of the Nikolčice Formation (Middle Jurassic, Callovian). The provenance and depositional environment of the Nikolčice Formation showed that deposition occurred within offshore, transitional zone, shoreface, foreshore and littoral sand bar environments; however, shoreface and foreshore deposits dominate in the cores studied. The crystalline units along the eastern margins of the Bohemian Massif represent the primary source of deposits of the Nikolčice Formation. An important role was played by acidic and intermediate plutonites and highly metamorphosed metasedimentary rocks (granulite and amphibolite metamorphic facies), which indicates an advanced stage of erosion of the source area. The role of volcanic and intrusive rocks was small. The primary source was followed by an additional recycled source from older sedimentary rocks (especially the Moravo-Silesian Paleozoic deposits – the Líšeň Formation, the Myslejovice Formation). A similarity of the source areas for the Nikolčice Formation and the underlying Gresten Formation was recognized. Identified differences in their source areas are mainly explained by varied erosional levels due to successive exhumation of the source Variscan orogen and possibly also by an expansion of the source area.
The deposits of the Gresten Formation (Middle Jurassic) obtained from deep wells in the territory of southern Moravia (Czech Republic) have been newly examined with the aim to better describe their provenance and depositional environment.Deposition within a relatively broad flood plain with fluvial/distributive channels, crevasse channels, crevasses splays and coal-swaps have been recognised in the majority of well cores.Open marine deposits are less common.The heavy mineral association is quite stable, with significant dominance of garnet and commonly also with high content of zircon.The mineralogical spectra of garnet types are broad with strong dominance of almandines.The rutiles were mostly derived from metapelites and additionally also from metamafic rocks and pegmatites.The results point to mixed sources from both intensively weathered crystalline rocks of the eastern margin of the Bohemian Massif (primary source) and the older sedimentary rocks -especially from the Moravo-Silesian Paleozoic deposits (recycled source).
Depositional environment and provenance of the Gresten Formation (Bajocian-Bathonian) and the Nikolcice Formation (Callovian) on the southeastern slopes of the Bohemian Massif (Czech Republic, subsurface data).)
Prace propojuje studium mramorů olesnicke skupiny moravika se studiem muskovit-plagioklasových poloh, ktere v ramci těchto mramorů tvoři uzavřene konkordantně uložene cocky. Mramory i muskovit-plagioklasove horniny byly studovany polarizacnim mikroskopem, katodoluminiscencnim mikroskopem a elektronovou mikrosondou. Po urceni mineralnich asociaci na jednotlivých lokalitach a po studiu reakcnich struktur pomoci katodoluminiscence byly sestaveny pravděpodobne metamorfni reakce na jednotlivých lokalitach ze kterých pak byly odhadnuty přibližne metamorfni podminky celeho komplexu hornin. Výsledky studia muskovit skapolitových poloh byly nasledně srovnany se starsim výzkumem, kde tyto polohy byly interpretovany jako ložni žily silně alterovaných silikaty chudých aplitů. Na zakladě nově zjistěných faktů, zejmena pak přitomnosti Cl bohatých skapolitů a dravitu spolu s celkovou pozici studovane horniny pak byla navržena teorie vzniku těchto poloh metamorfozou původně sedimentarnich hornin. Studium reakci v horninach pak ukazalo, že metamorfni stupeň větsi casti studovane oblasti odpovida P/T podminkam vzniku tremolitu, s výjimkou nejvýchodnějsi casti, kde je předpokladan metamorfni stupeň o něco nižsi.
We determine the organic matter content, its thermal maturity, genetic type, and source rock potential of the Miocene sedimentary rocks in the Czech Carpathian Foredeep. In the Czech Republic the Carpathian Foredeep represents a peripheral foreland basin formed due to the tectonic emplacement and loading of the Alpine-Carpathian Thrust Wedge onto the passive margin of the Bohemian Massif. Random vitrinite/huminite reflectance measurements and maceral analyses were performed on 25 samples from the Carpathian Foredeep succession. Additionally, results of 135 TOC content measurements, 141 Rock-Eval pyrolysis analyses and 27 vitrinite reflectance measurements were used to evaluate the regional distribution and depth trends for the entire Carpathian Foredeep. The thermal maturity of organic matter is between the immature part and peak of the oil window (Tmax = 413–448°C). Beneath the Western Carpathian Thrust Belt, the thermal maturity reaches higher values (Rr = 0.43–0.58%, Tmax = 429–448°C). The hydrocarbon generation potential is poor or fair, even if the total organic carbon values indicate good or even very good source rock potential. This is mainly due to the prevailing gas-prone Type III kerogen. The best source rocks were observed in the Miocene strata of the southern and central segments of the area discussed.
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