Control of Altyn Tagh Fault on the Jurassic shale gas in Western Qaidam Basin, north-west China

The shale of the Middle Jurassic Dameigou Formation in Western Qaidam Basin was developed with large thickness, high organic carbon content, and moderate thermal maturity, which means that it has the basic geological conditions for shale gas generation and accumulation are favourable. According to the comprehensive analysis, the Altyn Tagh Fault (ATF) did not uplift in the early-middle Jurassic period, and the Middle Jurassic stable lacustrine sedimentary strata were not affected by the strike-slip fault, which provided abundant material basis for shale gas generation. Due to the effect of later ATF left-lateral strike-slip activity, and the North-South tectonic extrusion movement, the abnormal overpressure derived from Dameigou Formation was formed, which can provide good preservation conditions for shale gas. The interaction between ATF activity and shale deposition jointly controlled the formation and preservation of shale gas in Western Qaidam Basin.