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Revising active fault maps in the Upper Franconia-Vogtland area: The newly discovered Selb-Aš-Plesná Creek Fault and its linked dry mofettes

One of the most tectonic active regions in central Europe is the Cheb Basin at the western margin of the Ohře/Eger Rift, which is characterized by earthquake swarms and spots of mantle-derived carbon dioxide exhalation (mofette, spring). This prompts the Geological Surveys of Bavaria and Saxony and their cooperation partners to detect suspected sites of gas exhalation in dry mofettes.

Digital elevation model-based geomorphic indices and color infrared image data were acquired to decipher fault systems and emphasize differences in vegetation. This led us to the finding of a ca. 20 km W-E-directed active fault system that extends from Selb-Reuth via Aš to Bad Brambach and finally borders the N-S-oriented Plesná-Počátky Fault. Throughout the fault zone, the conspicuity in the vegetation (circular cover of sedge and reed) points towards CO2 gas exhalation.

Geophysical reconnaissance at the Brambach spar garden confirmed the presence of gas caverns at the contact between the Fichtelgebirge/Smrčiny Granite and the mica schist. First emission measurements at the Brambach Mofette Field yield flux rates of ca. 16340 mg/(m²*h). Although significantly lower than in the mofettes of the Soos swamp, our results confirm the occurrence of a dry mofette in Saxony.

Details

Author
Alexander Repstock1, Jörg Büchner2, Johann Rohrmüller3, Jan Mrlina4, Ilona Vogel5, Marc Fröhlich5, Frank Rothe5
Institutionen
1Section of Geological Survey and Geophysics, Saxon State Office for Environment, Agriculture and Geology, Dresden, Germany; 2Section of Geology and Paleontology, Senckenberg Museum of Natural History Görlitz, Germany; 3Section of Soil and Rock Analytics, Bayerisches Landesamt für Umwelt, Marktredwitz, Germany; 4Institute of Geophysics, Czech Academy of Sciences, Prague, Czech Republic; 5Emissions Measurements, Reference, and Calibration Lab, Saxon State Company for Environment and Agriculture, Radebeul, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/j9ps-w508

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