Stable and radiogenic isotopes in pore waters from Leg 127, Japan Sea

Abstract

The isotopic composition is dominated by organic matter degradation, alteration of ash layers and volcaniclastic sands, silica transformation (opal A/CT), and basement alteration. Organic matter degradation and corresponding sulfate reduction leads to 32S depletion and is dependent upon sedimentation rate. The opal A/CT transformation may influence the oxygen isotopes and serves as a potential source for B, which is liberated at this interval at Site 795. Basement alteration processes dominate the sedimentary sequence below the opal A/CT transition, which serves as a chemical and physical boundary. The decreased in δ D and δ18O are probably related to a "paleo ocean water reservoir' situated in the permeable Layer II of the oceanic crust, as is indicated by the positive correlation between these two parameters. -from Authors