Concentrations and carbon isotopic compositions of CH4 and CO2 in gas from sediments of the Blake Outer Ridge, Deep Sea Drilling Project Leg 76.

Abstract

The principal gaseous carbon-containing components identified in the first 400m of sediment at Site 533, are methane (CH4) and carbon dioxide (CO2). Below a sub-bottom depth of about 25m, sediment cores commonly contained pockets caused by the expansion of gas upon core recovery. The carbon isotopic composition (delta13C per mille relative to PDB standard) of CH4 and CO2 in these gas pockets has been measured. Results imply that CH4 and CO2 incorporated in gas hydrates at this site are biogenic.-from Authors