Microbial Origin of Australian Coalbed Methane

Bituminous coal seam gases from the Permian Sydney and Bowen basins, Australia, are characterized by (1) methane/ethane ratios greater than or equal to 1000, (2) ^dgr13C and ^dgrD values for methane of -60 ±10^pmil PDB and -217 ±17^pmil SMOW, respectively, (3) carbon dioxide contents of less than 5%, and (4) ^dgr13C(CO<2-CH4) values of 55 ±10^pmil PDB. These data suggest that microbial reduction of CO2 rather than traditional thermogenic...