Abstract:

 On special geological conditions, the late hydrocarbon generation and accumulation can take place in older formations just as those in the Mesozoic and Cenozoic. The geothermal gradient is gradually decreased in Tarim Basin. The thermal evolution of the Lower Paleozoic was suspended frequently because of multiple uplift denudations of the overlying strata. Hence the organic matter evolution in the Lower Paleozoic was suspended. The differential burial evolution led to the differential thermal evolution in different structural belts. The hydrocarbon generation potential of source rock in some areas can be preserved up to Himalayan period. In Himalayan period, the source rock was buried deeply in short time so that the hydrocarbon was generated plentifully and accumulated efficiently. The activated fault systems in Neotectonic period made the hydrocarbon migration easy. These geological conditions caused the possibility of late hydrocarbon accumulation in Tarim Basin in the Lower Paleozoic. Tazhong, Lunnan and the deeper sites of Mangar Depression are the prospective areas.

Key words:

Key words: Tarim Basin; late hydrocarbon accumulation; geothermal gradient; burial evolution; formation erosion; tectonic activation