ULTIMATE FORMATION PERIOD OF PETROLIFEROUS BASIN IN THE WEST OF CHINA AND ITS RELATION WITH OIL AND GAS

Marginal faults of the five petroliferous basins in the west of China all up-thrust to the top. Pre-Quaternary strata thrust over Quaternary sediments, indicating that the petroliferous basins in the west of China and the surrounding older mountains were formed in Quaternary period. Because the basins were formed with the formation of compressive anticlines in the Quaternary structural layers, natural gas has been successfully found in the Quaternary structures in the Chaidamu basin. Therefore, attention should be paid to Quaternary oil and gas pools. The following four conclusions are given: (1)The five large petroliferous basins in the west of China were formed in Quaternary. (2)Quaternary anticlinal structure was made by Quaternary compressive structural force. (3)Quaternary oil and gas pools of Chaidamu basin are self-generating and self-storage type. (4)Even if there are no conditions to generate oil in the Quaternary, the following phenomenon should be taken into account that after pre-Quaternary oil and gas pools were destroyed by faults, the oil and gas could have migrated into Quaternary structural layers to form secondary oil and gas pools. So, we should pay attention to explorations of Quaternary oil and gas.