0000000000020561
AUTHOR
Tassi F.
Origin of methane and light hydrocarbons in the gas manifestations of Greece.
The geologic emissions of greenhouse gases (CO2 and CH4) give an important natural contribution to the global carbon budget. However, the contribution of these emissions to the global carbon cycle and their possible role on the climate change remain still poorly quantified (Guliyev and Feizullayev, 1997; Milkov, 2000; Etiope et al., 2015 and references therein). Methane, the most abundant organic compound in Earth's atmosphere, may be created either from existing organic matter or synthesized from inorganic molecules. Accordingly, it can be differentiated in two main classes: a) biotic (either microbial or thermogenic) and b) abiotic. For this study, 115 gas samples of fumarolic, thermal an…
Microbial methane oxidation leading to extreme isotopic fractionation in thermal springs of central Greece
The Greek territory belongs to the geodynamically active Alpine-Himalayan orogenic belt. As such, it shows intense seismic activity, active volcanic systems and areas of enhanced geothermal fluxes. One of these areas is the Sperchios basin and the northern part of Evia island in central Greece, which present widespread thermal manifestations (D’Alessandro et al., 2014). Five of them with temperatures from 33 to 80°C present bubbling gases whose dominating species are either CO2 or N2. All gases contain from 27 to 4000 ppm of CH4. The isotopic composition of CH4 in these gases covers a wide range with δ13C values ranging from -21.7 to +16.9 ‰ and δ2H values ranging from -124 to +301 ‰. The h…
Extreme isotope fractionation of hydrothermal methane due to oxidation processes in hot springs of Central Greece
The Greek territory belongs to the geodynamically active Alpine-Himalayan orogenic belt. As such, it shows intense seismic activity, active volcanic systems and areas of enhanced geothermal fluxes. One of these areas is the Sperchios basin and the northern part of Evia island in central Greece, which present widespread thermal manifestations [1]. Five of them with temperatures from 33 to 80°C present bubbling gases whose dominating species are either CO2 or N2. All gases contain from 27 to 4000 ppm of CH4. The isotopic composition of CH4 in these gases covers a wide range with δ13C values ranging from -21.7 to +16.9‰ and δ2H values ranging from -124 to +301‰. The hottest manifestation displ…
Light hydrocarbons as a proxy to identify the origin of the gas manifestations in Greece
The geologic emissions of greenhouse gases (CO2 and CH4) have an important natural contribution in the global carbon budget. Tectonics, through faults in geothermal and oil producing areas, play a significant role in the release of C-gases in many non-volcanic regions of the Earth. Methane, the most abundant organic compound in Earth’s atmosphere, has a potential global warming that is 28 times higher than that of CO2 on a 100-year time horizon. In this study, δ13C-CH4, δ2H-CH4 and light hydrocarbon (alkane: CH4, C2H6, C3H8, C3H6, i-C4H10, n-C4H10; alkene C3H6, iC4H8; and aromatic C6H6) gas concentration data of 119 gas samples (103 unpublished data and 16 literature data) from volcanic-hyd…
Etna International Training School of Geochemistry, 2018. Science meets practice.
Mount Etna, located in eastern Sicily, is the largest stratovolcano in Europe and one of the most intensely degassing volcanoes of the world (Allard et al., 1991; Gerlach, 1991). In particular, previous estimates highlighted that Mt Etna emits about 1.6 % of global H2O fluxes from arc volcanism (Aiuppa et al., 2008) and 10 % of global average volcanic emission of CO2 and SO2 (D’Alessandro et al., 1997; Caltabiano et al., 2004). Furthermore, Gauthier and Le Cloarec (1998) underscored that Mt. Etna is an important source of volcanic particles, having a mass flux of particle passively released from the volcano during non-eruptive period estimated between 7 to 23 tons/day (Martin et al., 2008; …