Abstract:

The seeping methane results in a special geological chemical micro-environment in marine gas hydrate geologic system. The anaerobic oxidation and reduction between methane and sulfate at sulfate-methane interface(SMI)induce mass of minerals，such as anthigenic carbonate, sulfides(AVS, pyrite)and sulfates(barite, gypsum),and so on. Because of the effect of sulfate reduce bacteria, the low δ³⁴S value of sulfide can compares with the high δ34S value of sulfate. The occurrence of such fractionation may be the common effect of the kinetic effects governed by the progresses of bacterial sulfate reduction and anaerobic bacterial disproportionation of elemental sulfur.

Key words: natural gas hydrate, geologic system, sulfur isotope, fractionation, progress