THE PRIMARY STUDY ON THE FORMATION OF OIL AND GAS FIELDS IN THE FORELAND BASINS IN CENTRAL AND WESTERN CHINA
中国中西部前陆盆地成藏特征的初步分析

The paper analyzes the hydrocarbon accumulation of gas pools in the western Sichuan foreland basin, northern Qaidam thrust and southern Junggar foreland basin. It indicates that the oil-gas fields were formed by multi-stage filling and that the gas pools accumulated in the late stages of the foreland basins. There were two most important stages for oil-gas accumulation in the foreland basins of central and western China, one was the Late Yanshanian movement when oil and gas accumulated mainly from Permian and Triassic source rocks of peripheral foreland basins in central China and rejuvenated foreland basins in western China, another during the Late Himalayan movement when oil and gas mainly from Meso-Cenozoic source rocks of rejuvenated foreland basins in western China and accumulated secondarily in gas fields of peripheral foreland basins in central China, affecting by neotectonic movement. The main source rock of foreland basins in central and western China is Mesozoic coal measure. They were matched for fault related fold cloures formed by thrusting and expulsion process from Mesozoic coal measure by much very thick sedimentation due to foreland development in Late Himalayan movement. In addition, it is concluded that the palaeostructure or palaeohigh was very important in hydrocarbon accumulation in forland basins and that the hydrocarbon distribution in phase state and genesis type was controlled by oilgas filling systems of early forland basins and late rejuvenated forelad basins.