关键词: 石油地质, 伸展聚敛旋回, 油气资源, 远景, 西北地区, 中国

Abstract: The Northwestern China had undergone three extensional and compressional cycles from Sinian to Devonian,Carboniferousto Triassic and Jurassic to Quaternary respectively,which caused a complex continental lithospheric block consisting mosaicallyof large or small cratons and orogenic belts.The sedimentary basins are characterized by superimposed geological structures,especially by the superimposition of foreland basins over the cratonic ones.The three periods of extension and transgression eventsof marine or lacustrine had resulted in three successions of regional source rocks,including the Cambrian to Ordovician,Carboniferous to Permian and Jurassic rocks,and constituted accordingly the lower,middle and upper assemblages of source-reservoirseals as a result.The three periods of compression,however,had formed large numbers of traps.The matching of the time ofmaturation of source rocks with the time of trap formation has controlled the four critical moments for oil and gas to accumulate.The NW China is famous for its rich petroleum resources,and favorable environments of foreland and cratonic basins for poolformation as well.The tectonic elements of the basins have played an important role in oil and gas pool formation and occurrencesof large-scaled oil and gas accumulations.The NW China shows broad prospects for hydrocarbon exploration,while the cratonicand foreland basins are the two predominant targets for the further exploration.

Key words: petroleum geology, extensional and compressional cycle, petroleum resources, prospects, northwestern region, China