Anoxic diagenesis and methane generation in sediments of the Blake Outer Ridge, Deep Sea Drilling Project Site 533, Leg 76.

Abstract

Concentrations and delta34S and delta13C values were determined on SO42-, HCO3-, CO2, and CH4 in interstitial water and gas samples from the uppermost 400m of sediment. These measurements provide the basis for detailed interpretation of diagenetic processes associated with anaerobic respiration of electrons generated by organic-matter decomposition. Input-output carbon isotope-mass balance calculations, and carbonate system equilibria in conjunction with observed CO2-CH4 ratios in the gas phase, independently suggest that CH4 concentrations on the order of 100 mmol kg-1 are present in the pore waters.-from Authors