Paleogene sedimentary facies and their evolution in the Tangyuan fault depression, eastern Heflongjiang, China

Three sedimentary facies,seven sedimentary sub-facies and seventeen sedimentary micro-facies are recognized in the Tangyuan fault depression from studies of the types and evolution of Paleogene sedimentary facies,using the core data,well-logging data of 29 wells and 1028 km long 2D seismic survey data.It is suggested that:lake-bottom fan facies and lake facies are developed along the steep slope of the Tangyuan fault depression,the fan-delta is developed on the gentle slope of the depression,and the lake-bottom fan and fan-delta exist in the central secondary uplift near the depression.The Paleogene lake basin of the Tangyuan fault depression experienced a process from small to large and again to small.