Geochemistry and distribution of spring gases and the tectonic structure of the Eger Rift in Oberpfalz and Oberfranken, Bavaria.

Weinlich, F. H.; Bräuer, Karin; Kämpf, Horst; Strauch, Gerhard; Tesař, Jiři; Weise, Stephan M.

doi:10.1127/zdgg/154/2003/67

Cited by 8 publications

(7 citation statements)

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“…More details about the seismic network could be found in Fischer et al (2010). The region is also known for its diffuse CO 2 degassing often manifested by moffets, mineral springs and gas vents (Weinlich et al 1998;Heinicke & Koch 2000;Bräuer et al 2003). The anomalous high concentration of mantle-derived 3 He indicates magmatic reservoirs at mantle depth (e.g Bräuer et al 2007).…”

Section: A P P L I C At I O N T O N W B O H E M I a E A Rt H Q Ua K E...mentioning

confidence: 99%

Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences

Dahm

Fischer

2013

Geophysical Journal International

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Crustal earthquake swarms are an expression of intensive cracking and rock damaging over periods of days, weeks or month in a small source region in the crust. They are caused by longer lasting stress changes in the source region. Often, the localized stressing of the crust is associated with fluid or gas migration, possibly in combination with pre-existing zones of weaknesses. However, verifying and quantifying localized fluid movement at depth remains difficult since the area affected is small and geophysical prospecting methods often cannot reach the required resolution.We apply a simple and robust method to estimate the velocity ratio between compressional (P) and shear (S) waves (v P /v S -ratio) in the source region of an earthquake swarm. The v P /v S -ratio may be unusual small if the swarm is related to gas in a porous or fractured rock. The method uses arrival time difference between P and S waves observed at surface seismic stations, and the associated double differences between pairs of earthquakes. An advantage is that earthquake locations are not required and the method seems lesser dependent on unknown velocity variations in the crust outside the source region. It is, thus, suited for monitoring purposes.Applications comprise three natural, mid-crustal (8-10 km) earthquake swarms between 1997 and 2008 from the NW-Bohemia swarm region. We resolve a strong temporal decrease of v P /v S before and during the main activity of the swarm, and a recovery of v P /v S to background levels at the end of the swarms. The anomalies are interpreted in terms of the Biot-Gassman equations, assuming the presence of oversaturated fluids degassing during the beginning phase of the swarm activity.

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Section: A P P L I C At I O N T O N W B O H E M I a E A Rt H Q Ua K E...mentioning

confidence: 99%

Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences

Dahm

Fischer

2013

Geophysical Journal International

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“…Furthermore, a shift of the nests hot spots towards the NW-SE trending Erbendorfer fault line in MG is suggested to be caused by stronger degassing of the tectonically and structurally controlled Erbendorfer fault line, which promotes RWA nests settlements [16,19]. It is hypothesized that this process is triggered by regional seismicity (Figure 1a) as an important driving force causing microfracturing [42,43,86,87]. These new fractures provide pathways for juvenile fluids with mantlederived CO2 and Helium to migrate over long distances, indicating hidden volcanic structures in the vicinity of these degassing sites [86,87].…”

Section: Geobio-interactionsmentioning

confidence: 99%

“…It is hypothesized that this process is triggered by regional seismicity (Figure 1a) as an important driving force causing microfracturing [42,43,86,87]. These new fractures provide pathways for juvenile fluids with mantlederived CO2 and Helium to migrate over long distances, indicating hidden volcanic structures in the vicinity of these degassing sites [86,87]. Additionally, seismic events lead to the formation of new emanation surfaces and pathways and a significant increase in the radon signal, although the applied stress remains constant over time [88].…”

Section: Geobio-interactionsmentioning

confidence: 99%

Re-inventories at two study sites in the Oberpfalz (Bavaria, Germany): Increase in RWA nests, herb biodiversity and dead wood in sustainably managed forests

Berberich,

Berberich

2024

Preprint

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The outstanding occurrences of red wood ant nests (RWA; Formica rufa-group) at two study sites in the Oberpfalz, NE Bavaria, Germany, could be confirmed by the 2023 re-inventory (a total of 5,393 nests and an increase by ≈8 %). RWA nests preferred mature and medium mature pine-dominated forests. Standing and downed dead wood do not negatively influence nests. Nest counts with woodpecker cavities and the diversity of the herb layer increased. The highly clustered nests in NW-SE direction suggests a strong interaction between nests distributions and the tectonic environment. Our developed (re-)inventory approach in combination with the comprehensive photo database is a valuable tool for a) monitoring the entire forest habitat including woodpecker cavities and dead wood in, at and around nests, and b) identifying GeoBio-Interactions. Such a comprehensive approach leads to more accurate and realistic counts of RWA nests during (re-)inventories and provides scientific evidence of the status quo of RWA occurrence. Our results disproved the unfounded and scientifically unsubstantiated blanket statement by laymen of the ASW Landesverband Bayern e.V. that RWA nest numbers in the Oberpfalz or even in the entire Bavaria are in sharp decline. We suggest seven to eight years as a suitable time interval for re-inventories.

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“…The Eger Rift, located in West Bohemia (Czech Republic), is characterized by active mantle degassing of CO 2 and thus serves as a natural analog site for CCS. It's reasonable to assume that degassing has been ongoing since the mid-Pleistocene (Weinlich et al, 1999), releasing high amounts of CO 2 for roughly 1 million years. Measurements of gas emissions at one of the known Eger Rift Mofette fields in Hartusov varied between ∼ 14 and 43 kg m −2 d −1 (Nickschick et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Enrichment of rare methanogenic Archaea shows their important ecological role in natural high-CO2 terrestrial subsurface environments

et al. 2023

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IntroductionLong-term stability of underground CO2 storage is partially affected by microbial activity but our knowledge of these effects is limited, mainly due to a lack of sites. A consistently high flux of mantle-derived CO2 makes the Eger Rift in the Czech Republic a natural analogue to underground CO2 storage. The Eger Rift is a seismically active region and H2 is produced abiotically during earthquakes, providing energy to indigenous microbial communities.MethodsTo investigate the response of a microbial ecosystem to high levels of CO2 and H2, we enriched microorganisms from samples from a 239.5 m long drill core from the Eger Rift. Microbial abundance, diversity and community structure were assessed using qPCR and 16S rRNA gene sequencing. Enrichment cultures were set up with minimal mineral media and H2/CO2 headspace to simulate a seismically active period with elevated H2.Results and discussionMethane headspace concentrations in the enrichments indicated that active methanogens were almost exclusively restricted to enrichment cultures from Miocene lacustrine deposits (50–60 m), for which we observed the most significant growth. Taxonomic assessment showed microbial communities in these enrichments to be less diverse than those with little or no growth. Active enrichments were especially abundant in methanogens of the taxa Methanobacterium and Methanosphaerula. Concurrent to the emergence of methanogenic archaea, we also observed sulfate reducers with the metabolic ability to utilize H2 and CO2, specifically the genus Desulfosporosinus, which were able to outcompete methanogens in several enrichments. Low microbial abundance and a diverse non-CO2 driven microbial community, similar to that in drill core samples, also reflect the inactivity in these cultures. Significant growth of sulfate reducing and methanogenic microbial taxa, which make up only a small fraction of the total microbial community, emphasize the need to account for rare biosphere taxa when assessing the metabolic potential of microbial subsurface populations. The observation that CO2 and H2-utilizing microorganisms could only be enriched from a narrow depth interval suggests that factors such as sediment heterogeneity may also be important. This study provides new insight on subsurface microbes under the influence of high CO2 concentrations, similar to those found in CCS sites.

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Geochemistry and distribution of spring gases and the tectonic structure of the Eger Rift in Oberpfalz and Oberfranken, Bavaria.

Cited by 8 publications

References 0 publications

Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences

Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences

Re-inventories at two study sites in the Oberpfalz (Bavaria, Germany): Increase in RWA nests, herb biodiversity and dead wood in sustainably managed forests

Enrichment of rare methanogenic Archaea shows their important ecological role in natural high-CO2 terrestrial subsurface environments

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