Extractable hydrocarbon and carbon isotope geochemistry of Lower Cretaceous sediments of the Exmouth Plateau

These sequences represent distal portions of the Mesozoic Barrow delta, in which petroleum source rocks and reservoirs exist on the Australian continent.

The organic matter at the ODP sites is thermally immature type III material. Biomarker hydrocarbon compositions are dominated by long-chain, waxy n-alkanes and by C29 steranes, which reflect the land-plant origin of organic matter. Organic carbon d13C values ranged from -26 per mil to -28 per mil, consistent with a C3 land-plant source.