STUDY ON THE INFILLING PATTERNS OF LACUSTRINE BASINS IN THE DONGYING DEPRESSION

The infilling patterns of lacustrine basins are the important means to evaluate the sedimentary characteristics of hydrocarbon source rocks.Combined with the geochemical characteristics of source rocks in this paper,the sedimentary succession of source rocks,the developing features of strata and the infilling and evolutionary process of basins in the Lower Triassic Shahejie Formation of the Dongying Depression were analysed.The source rocks of the Shahejie Formation can be divided into three evolutionary stages from lower to upper.The evaporite facies(the Upper Shasi Subformation),the oscillatory deep lake facies(the Lower Shasan Subformation)and the delta lacustrine facies(the Middle and Upper Shasan Subformation)assemblage patterns were established,which corresponding to underinfilling,equilibrium infilling and overinfilling lacustrine types respectively.They reflected the generation,spreading and consumption process of lakes.