SEQUENCE STRATIGRAPHIC CHARACTERISTICS OF FLUVIAL FACIES IN THE QUANTOU FORMATION OF BUHAIHELONG AREA, THE SONGLIAO BASIN

Based on the developing characteristics of fluvial facies and each sequence stratigrahic unit in the Quantou Formation of Buhaihelong area,the Songliao Basin,which was observed in outcrop,core and seismic data,the differences among the formation mechanism of three stream types were analysed from the angles of allogenic cycles and authigenic cycles.According to the controlling factor of allogenic cycles,that is,the changes of the base level,the sequence stratigraphic framework of the study area was divided,and the sequence stratigraphic model of fluvial facies was established.The lowstand system tract (LST) is dominated by lateral accretion and characterized by developing braided streams;the transgressive system tract (TST) is dominated by vertical accretion and characterized by developing reticulated streams;the highstand system tract (HST) is dominated by lateral accretion and characterized by developing lowenergy meandering streams;and the regressive system tract (RST) is dominated by lateral accretion and characterized by developing highenergy meandering streams.