Effective Petroleum Source Rocks of the World: Stratigraphic Distribution and Controlling Depositional Factors

AAPG Bulletin 75(12): 1809–1851. Six stratigraphic intervals, together one-third of Phanerozoic time (Silurian, Upper Devonian–Tournaisian, Pennsylvanian–Lower Permian, Upper Jurassic, middle Cretaceous, Oligocene–Miocene), contain the source rocks that generated more than 90% of the world's discovered oil and gas; the distribution shows no cyclicity, is controlled by geologic age, paleolatitude, structural setting and the evolution of biota, and almost 70% of reserves were generated since the Coniacian. The mainstream stratigraphic account of where the world's petroleum comes from.