The enrichment of 34S in the solfataras of the Nea Kameni volcano, Santorini archipelago, Greece

Abstract

Sulfur isotope investigations carried out on elemental sulfur and sulfates of the Nea Kameni solfataras, Santorini, Aegean Sea, Greece, show a clear enrichment in the heavy sulfur isotope 34S against the assumed primordial 32S34S ratio of 22,220. Within the same crater, different vents, only a few meters apart from each other, produced δ differences up to 10‰, which remained constant for several years. This enrichment is most probably due to contamination by heavy sulfur from a nonvolcanic source. An enrichment in the same order of magnitude was observed in sulfur of recent and older lavas (δ 34S = −1 − +11‰).Potential contaminants like sulfide sulfur in hydrothermal ore veins of Athinios has a δ 34S mean value close to 0‰, sulfide and sulfate in the sedimentary basement has a δ 34S mean value of +2.6‰. Seawater sulfate from the area gives a value of δ 34S = 20‰, while sulfide from bacterial reduction of pore-water sulfate in recent iron ore sediments has δ 34S values between −8 and −5‰. Sulfate remaining in the pore solutions gave δ 34S = +27‰.The most probable explanation for the observed high δ 34S values in the solfataric sulfur and in some of the lavas of the Santorini area is contamination of the volcanic vents by Mediterranean Sea water.