Characteristics Of Sedimentary System Of Cretaceous Shahezi Formation In Jinshan Area

In this paper,through the stratigraphic division and comparison of the Cretaceous Shahezi Formation in the Jinshan area of the Lishu fault depression in the southern margin of the Songliao Basin,combined with the comprehensive interpretation of drilling and seismic data,the sequence division of the Shahezi Formation is determined;based on the analysis of the fault system in the Jinshan area On the basis of a comprehensive analysis of the source-transport system of the Shahezi Formation,the distribution characteristics of the sedimentary facies of the Shahezi Formation in the Jinshan area are studied.The study yielded four main understandings:(1)The formation of the Shahezi Formation in the Jinshan area is divided into two third-order sequences SQ3 and SQ4,which correspond to the first and second sections of the Shahezi Formation respectively.(2)There are two types of fault tectonic systems in Jinshan area: nearly north-south extensional faults and north-east twisted faults.The complex interaction of the fault systems controls the phased subsidence in Jinshan area and the phased tectonic uplift in the south-southeast area And differential erosion,which in turn affect the characteristics of fault development,paleomorphology,provenance supply,etc.in the study area.(3)During the deposition period of the Shahezi Formation,the lake basin in the study area continued and rapid subsidence,resulting in the development of the lake-fan delta system deposition in the first section of the Shahezi Formation;during the deposition period of the second section of the Shahezi Formation,the lake water range expanded and the southwest slope of the study area Fan delta deposits mainly develop in the belt,alluvial fan-fan delta deposits develop in the northern steep slope zone,and lake deposits develop in the deep depressions in the north.