Abstract: Based on analyses of data including neotectonics earthquake,drilling,seismic,stratigraphy,structural features and satellite remote sensing,it is believed that Himalayan movement can be divided into three episodes in Songliao basin.The first and third episodes have mainly been affected by the Indian plate and result in NE SW regional principal compressive stress;while the second episode has mainly been affected by the Pacific plate and has given rise to NW-SE or nearly W-E regional principal compressive stress;the NW tectonism in the third episode has important effects on the early formed structural traps and the remigration and accumulation of hydrocarbons in those traps.The Tertiary in Songliao basin was deposited in a compresso depressed basin,characterized by limited distribution of formations,coarse grained clastics,and the uplifted area to be the provenance.Analysis of the Tertiary tectonic deformation ellipsoid in Songliao basin reveals that the direction of compressional stress turned from N-S to nearly W-E in the middle and late Paleogene(since 43 Ma).Under compression at the end of Cretaceous,the moderate depth and shallow structures grew progressively and provided good traps for hydrocarbon accumulation.The moderate depth and shallow faults are the result of superposition of multistage fracturing,and faults formed in different stages have different extending characteristics.NE and NNE faults were mainly developed under nearly E-W extensional stress during the deposition of Qingshankou Formation;only the nearly E-W faults were developed under nearly S-N extensional stress at the end of deposition of Yaojia Formation;and the NNW and NW faults were mainly developed under left lateral compresso shear stress after the deposition of Mingshui Formation.Structural inversion at the end of deposition of Mingshui Formation has resulted in the Songliao basin entering the peak of hydrocarbon generation;and changes of direction of compressional force has resulted in the opening of shallow and moderate depth old faults with different directions,which would consist of multi directional migration pathways.The compressional setting would not only provide pathways and reservoirs for hydrocarbon migration and accumulation,but would also be favorable for generation and preservation of hydrocarbons,thus realizing good matching of hydrocarbon generation,migration,accumulation and preservation.

Key words: Songliao basin, Himalayan orogeny, Tertiary, petroliferous property, impact