Evolution of the Cryogenian cratonic basins in China, paleo-oceanic environment and hydrocarbon generation mechanism of ancient source rocks, and exploration potential in 10,000 m-deep strata

Deep and ancient strata are significant successor fields for future oil and gas exploration. Recently, a unit of thick high-quality interglacial black rock series was discovered between two sets of Cryogenian tillites in China. As a potential effective petroleum source rock, this rock series has drawn wide attention but is yet to be fully investigated. The formation mechanism, distribution, and hydrocarbon generation potential of the interglacial source rock remains unclear, hindering the estimation of the exploration potential in the Cryogenian. The Sturtian and Marinoan, the two global glacial events during the Cryogenian, led to extreme cold climate and caused distinct disruption of the Earth’s carbon cycle. Whilst the organic-matter-rich black rock series formed during the interglacial periods, as an important carbon pool, has close relationship with glacial events. Here we report the latest advances in the study of Cryogenian in the South China and Tarim cratons, including the evolution of the Cryogenian cratonic basins, paleo-oceanic environment, formation model of ancient source rocks, and hydrocarbon generation characteristics. Through integrated analyses of outcrop, drilling, seismic, elemental, and isotopic data, in combination with previous studies, we reviewed the evolution of South China and Tarim cratonic basins during the break-up of the Rodinia supercontinent, and the control of geo-tectonic settings on the intracratonic rifts. Moreover, we summarized the influence of intracratonic rifts on the development of glacial deposits, and the paleo-oceanic conditions and paleo-productivity during the formation of interglacial source rock. The formation model, distribution pattern of the Cryogenian source rock and its resource potential have been investigated as well. On this basis, we further estimated the petroleum exploration potential in ultra-deep strata and sketched the major exploration areas in 10,000 m-deep strata, which will be of great significance for the petroleum geology theory and exploration activities in ultra-deep and ancient strata.