Active degassing of crustal CO2 in areas of tectonic collision: A case study from the Pollino and Calabria sectors (Southern Italy)

Carbon dioxide (CO 2 ) is released from the Earth’s interior into atmosphere through both volcanic and non-volcanic sources in a variety of tectonic settings. A quantitative understanding CO outgassing fluxes different geological settings thus critical for decoding link between global carbon budget natural processes (e.g., eruption earthquake nucleation) effects on climate evolution over time. It has recently been proposed that degassing areas major component emission budget, but available data are still sparse incomplete. Here, we report results geochemical survey aimed at quantifying emissions cold thermal springs tectonically active Pollino Massif Calabrian arc (Southern Italy). The chemical ad isotopic (He C) composition fifty-five dissolved gas samples allows to identify two domains: 1) shallow system dominated by components atmospheric signature (helium, hereafter He) biogenic origin (C), 2) deeper which crustal/deep fluids dominant. measured He isotope ratios range 0.03 1.1 Ra (where ratio atmosphere) revealing variable contamination. Furthermore, indicate presence traces mantle contributions (2%–3%) groundwater. prevailing low R/Ra values reflect addition crustal radiogenic 4 during groundwater circulation. Using helium data, explore possible secondary (dissolution/precipitation) act modify chemistry pristine volatiles. For springs, estimate deep C output 2.3 x 10 7 6.1 8 mol year −1 . These correspond per square km comparable with those estimated several inactive continental regions affected metamorphic southern margin Tibetan Plateau).