RESEARCH OF SEDIMENTARY FACIES OF FORTH MEMBER OF YINGCHENG FORMATION IN XUJIAWEIZI FAULT DEPRESSION IN THE SONGLIAO BASIN

The Xujiaweizi Fault Depression is a half graben-like fault basin that is fault in the west and transgression in the east in tectonic style,and that is thicker in the west and thinner in the east in formation thickness.There have the characteristic of multi-depocenter,many and near matter source.The volcano is the main matter source in Anda aera.By means of the research of rock core observation more than 20 wells,and well logging,seismic,test data and so on,there has chiefly a set of coarse fragment sedimentation of river and lacustrine facies from gritstone to cobblestone in K1yc4;there are 7 lithofacies types and 5 depositional systems.In it,there are fan delta sedimentary system in the north of research area in the lower member of K1yc4,there are alluvial fan and flood basin in the south.There are mainly braided delta sedimentary system in the east of Songxi Fault and fan delta sedimentary system in the west of Songxi Fault in the upper member of K1yc4;there are mainly delta sedimentary system in the south.But there are shore and mere sediment in the front of every depositional system.