Principal Investigator Shuhei Ono
Sulfide sulfur in mid-oceanic ridge hydrothermal vents is derived from leaching of basaltic-sulfide and recycled seawater-sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because δ34S values of vent fluid H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. We show that delta-33S (≡ δ33S – 0.515 δ34S) values can decouple isotope mixing and exchange because they result in different delta-33S values of up to 0.04 ‰ even if δ34S values are identical.