Publication Date:
2021-12-03
Description:
We report on the results of an extensive geochemical survey of fluids released in the Vardar
zone (central-western Serbia), a mega-suture zone at the boundary between Eurasia and Africa plates.
Thirty-one bubbling gas samples are investigated for their chemical and isotopic compositions (He, C,
Ar) and cluster into three distinct groups (CO2-dominated, N2-dominated, and CH4-dominated) based
on the dominant gas species. The measured He isotope ratios range from 0.08 to 1.19 Ra (where Ra is the
atmospheric ratio), and reveal for the first time the presence of a minor (〈20%) but detectable regional
mantle-derived component in Serbia. δ13C values range from −20.2‰ to −0.1‰ (versus PDB), with
the more negative compositions observed in N2-dominated samples. The carbon-helium relationship
indicates that these negative δ13C compositions could be due to isotopic fractionation processes during
CO2 dissolution into groundwater. In contrast, CO2-rich samples reflect mixing between crustal and
mantle-derived CO2. Our estimated mantle-derived He flux (9.0 × 109 atoms m−2 s−1) is up to 2 orders
of magnitude higher than the typical fluxes in stable continental areas, suggesting a structural/tectonic
setting favoring the migration of deep-mantle fluids through the crust.
Description:
Published
Description:
e2021GC010017
Description:
9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
