Cretaceous deposits, covered by Quaternary sediments in the Osterzgebirge (Saxony) between Bad Gottleuba and Bornersdorf have been investigated. Beside the interpretation of existing drill logs, 15 new short wells were drilled as well as three seismic profiles were shot. Samples were taken for micropaleontologic analysis. The existence of Upper Cretaceous marls with a lateral extent of about 500 by 600 metres was proven. Due to the results of the seismic and stratigraphic interpretation, a thickness of 250 to 300 m of sediments can be assumed. The Cretaceous deposits are bounded by NW-SE and NE-SW striking faults. The foraminifera assemblage indicates early to middle Coniacian age of the marls. From the occurrence of Cenomanian and lower Turonian sandstones nearby a fairly complete upper Cretaceous succession can be concluded. The origin of such a narrow delimited basin, with such a huge depth is not yet fully understood. At present we suggest that a pull-apart-basin is responsible for the preservation of the sediments.
The airborne gamma-ray spectrometry images from the Czech and German parts of the Carboniferous Altenberg-Teplice Volcanic Complex (ATVC) -both obtained during independent surveying campaigns -were merged to display the structure of the caldera fill (dominated by rhyolitic ignimbrites) and associated intrusive bodies.The airborne systematic measurements were supported by the ground-and laboratory gamma-ray spectrometry analyses (K, U, Th) of representative lithologies from outcrops and drill-cores.Significant differences were identified between the younger and older (post-and pre-caldera respectively) intrusive complexes related to the ATVC.The younger Schellerhau granite displays 1.5-3.0×higher concentrations of radioactive elements than the older Fláje granite.The ATVC was found to be split by the NW-SE trending Altenberg Fault into a southern and a northern segment that expose different stratigraphic levels of the caldera's fill.The individual types of rhyolite ignimbrites defined in the Czech part of the ATVC are characterized by distinct concentrations of natural radioactive elements which enable identification of the individual types from the airborne gamma-spectrometry image.These characteristics were compared to data obtained from the German part, and several lithological types were unified to common units.A single Th-rich unit (Pramenáč type in Czech part, Lugstein type in Germany and Teplice Rhyolite TR3a in Mi-4 borehole) can be traced across the entire caldera and may serve as the principal correlation member.Inclusion of the Vrchoslav type into this TR3a unit remains speculative due to lack of data, and further petrological research is required.On the other hand, Vlčí kámen and Medvědí vrch types from opposite sides of the caldera display identical properties allowing to merge them into a common unit TR3b overlain by the youngest unit TR4 (Přední Cínovec type) -restricted to the Czech territory.This result may suggest partly synclinal structure within the southern ATVC segment.The TR4 unit has a strong compositional tendency towards the post-ignimbrite granite porphyry intrusions.Some lithotypes in the northern segment (e.g., Buschmühle) do not have counterparts on the Czech side and most likely represent an independent volcanic unit in the northern, presumably older, part of the caldera.The uniform composition of the rhyolitic rocks observed in the entire profiles of the drillings located in the Town Teplice (TP-39 reaching 1170 m depth) may suggest that the main feeding conduit system for the TR4 ignimbrite was located within the Teplice-Lahošť horst area.
Abstract The contemporary occurrence of juvenile gas emissions at springs or mofettes in active volcanic areas can be observed worldwide. This correlation is less frequent in areas with dormant or post-volcanic activity. The NW-Bohemia/Vogtland region located at the Eger rift zone (Czech Republic) provides an intriguing example of this correlation between numerous Neogene-aged post-volcanism locations and juvenile fluid emission sites. Newly discovered dikes and diatremes are located close to vents with the highest helium isotope ratios ( 3 He/ 4 He) of about 6 R a . Our results lend support to the hypothesis that feeder dikes and their fractured wall rocks should be considered the predominant conduits for the continuous upwelling of juvenile fluids. Moreover, 77% of the CO 2 gas emission sites are located close to dikes or diatremes, i.e., within a distance of 4 km. Our studies reveal a spatial dependence of the R a values at the spring sites with the estimated distances to the basaltic bodies. The results confirm the negative trend known from the literature. That is, R a values decrease with increasing distance from the feeder dikes.
Tectonics modify the base-level of rivers and result in the progressive erosion of landscapes. We propose here a new method to classify landscapes according to their erosional stages. This method is based on the combination of two DEM-based geomorphic indices: the hypsometric integral, which highlights elevated surfaces, and surface roughness, which increases with the topographic elevation and the incision by the drainage network. The combination of these two indices allows one to produce a map of erosional discontinuities that can be easily compared with the known structural framework. In addition, this method can be easily implemented (e.g., in MATLAB) and provides a quick way to analyze regional-scale landscapes. We propose here an example of a region where this approach becomes extremely valuable: the Ore Mountains and adjacent regions. The lack of young stratigraphic markers prevents a detailed analysis of recent fault activity. However, discontinuities in mapped geomorphic indices coupled to the analysis of river longitudinal profiles suggest a tight relationship between erosional discontinuities and main tectonic lineaments.
A b s t r a c t . The article presents the cross-border cooperation of geologists from the Lower Silesian Branch of Polish Geological Institute and the national geological surveys of the Czech Republic and Germany. The current cooperation is discussed on the basis of Geological Map Lausitz–Jizera–Karkonosze as well as on geological research of the Muskau Arch. The Geological Map Lausitz–Jizera–Karkonosze, in 1 : 100,000 scale, with Comments, presents the geology of the north-western part of the Bohemian Massif. A short geotectonic evolution of the area from Neoproterozoic to Cenozoic is presented. The results of Polish-German geological research and inventory of so-called “geotopes” are the basis to establish a cross-border Muskau Arch Geopark.