Microbial hydrocarbon gases in the Witwatersrand Basin, South Africa: Implications for the deep biosphere1 1Associate editor: R. Summons

In this study, compositions and δ13C and δ2H isotopic values of hydrocarbon gases from 5 mines in the Witwatersrand basin, South Africa, support the widespread occurrence of microbially produced methane in millions of years-old fissure waters. The presence of microbial methane is, to a large extent, controlled by the geologic formations in which the gases are found. Samples from the Witwatersand Supergroup have the largest microbial component …