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Abstract

Microbial processes in the so-called ’Deep Biosphere‘ and the link to geological processes are not well understood. We hypothesize that in active fault zones and especially in CO2-conduits, due to an intensified substrate support, microbial processes are significantly accelerated compared to other continental Deep Biosphere ecosystems. Therefore active fault zones could be seen as ‘Hot Spots’ of microbial life in the deep subsurface. The Cheb Basin (Czech Republic) is a shallow Neogene, intracontinental basin filled with fluvial and lacustrine sediments. The intersection area of the north-south striking Počatky-Plesná Fault zone with the northwestsoutheast directed Mariánské Lázně Fault Zone is nearly permanently seismically active (earthquake swarms up to M 4.5). South of the epicentral area two CO2-diffuse degassing structures are visible on a decameter scale. The CO2-conduits are considered as important structures for the understanding of lithospheric mantle-crust interaction processes via mantle fluids, however rock-fluid and geo-bio interactions are barely understood in this system. Moreover, there are hints that the microbial turnover in this region, e.g. CH4 production, is significantly accelerated after earthquakes. In the frame of a DFG project a pre-examination study to a planned international ICDP-drilling campaign started, which includes a 120 m deep drilling at the Hartoušov mofette field. The aim of the study is to get first insights into the microbial community structure by applying modern high-throughput DNA sequencing techniques and geochemical analysis.