Abstract:

Yanji Basin,located in the east part of Jilin Province with an area of1000km²,is a Meso-Cenozoic basin formed on Hercynian granite and metamorphic rocks during late Indosinian movement.The greatest buried depth of the basement is 3400m.The basin in geotectonic position belongs to Yongji-Aohan fault-folded belt of Tianshan-Xinganling fault-folded System.X-shaped and H-shaped faultsystems controlled the formation and development of the basin.Three first-order structural units can be divided within the basin.Besides,a secondary structural belt—central uplift belt has been discovered by interpretation of landsat photographs and aeromagnetie data.Through the analysis of paleotectonic stress field,the basin is determinedto be stretch origin;the activities of Hegang-Qingjin fault belt have playeda leading role in its formation.The basin contains mainly Cretaceous sediments,then Tertiary depositsand great deal Jurassic volcanic rocks,in which asphalt sandstone,asphalticvein and geochemical exploration abnormality have been found.According to the analysis of the source rock,the authors considered thatsandy shale member of the Lower Cretaceous Dalazi Formation that contains abundant organic matter and is matured has oil forming potential to someextent.So it is inferred that the most favourable place for oil enrichment isthe central uplift belt.