Study on the formation and evolution of deep structure of Xujiaweizi fault depression

Xujiaweizi fault depression is the most important gas-bearing fault depression in the deep of Songliao basin.On the basis of the latest seismic and drilling data research achievements,this article research the formation and evolution of Xujiaweizi fault depression again,combining with the recognition of predecessors.Xujiaweizi fault depression is situated in the north of Songliao basin, and on the western slope of Moho uplift in regional tectonic position,the specific position of Xujiaweizi fault depression has decided that its every stage of formation and evolution is controlled by the tectonic movement of northern regional plate.It also has certain relationship with formation and evolution of Songliao basin.We can divide the formation and evolution of Xujiaweizi fault depression into five stages,which is the result of development and formation course of interaction of Pacific tectonic plates and action of deep thermal.This periodic cycles of processing has created the present geological structure with the characteristic,which is different segmentation from south to north,various zones from east to west,alternating with protruding and sunken belt,structurally complex and sedimentary coexist with volcanic rocks.Xujiaweizi fault depression deep zones are controlled by four sets of faults,such as nearly north-west Xuzhong fault,nearly south-north Xuxi fault,nearly north-west Xudong fault belt and four groups of nearly north-east fault. This research offers well interpretations for a lot of the past geological phenomena we can' t explain,and obtains some new recognition, which gives effective guidance to find natural gas resource from macro-level at the same time.