RELATIONSHIP BETWEEN SEDIMENTARY FACIES AND GRAIN SIZE DISTRIBUTION OF THE SONGLIAO CRETACEOUS SEQUENCE,NE CHINA
Liu Wanzhu; Liu Zhaojun; Wang Dongpo(Changchun University of Earth Sci. , Changchun 130026)
Songliao Basin,situated in the northeast part of China,is an oil and gas bearing Mesozoic sedimentary basin of the NNE direction with an area about 260 000 km2.Based on the sedimentological study of outcrops and cores in the basin and also that of the logs,as well as the seismic data,the authors identify and classify the Cretaceous strata into ten sedimentary.facies within the Songliao Basin. They are alluvial fan,fluvial plain, fan-delta,delta,shore shallow lacustrine,beach flat,semideep-deep lacustrine,subaquatic gravity flow,lacustrine bog,and volcanic-pyroclastic facies.The grain size analysis of the sedimentary sequence above shows that there is a significant correlation between grain size distribution and sedimentary faciles. And in turn we can use the characteristrics of grain size distribution to idntify the typfes of sedimentary facies,The mechanism why the relationship can exist between grain size and facies is also discussed.