ON THE SEDIMENTATION OF THE BARRIER BAR AND SLOPE APRON OF THE DAMOGUAIHE FORMATION, UPPER JURASSIC, IN THE WURXUN DEPRESSION, THE HAILAR BASIN

Based on the data of drilling cores, seismic stratigraphy and loggings, the sedimentary analysis are made on the barrier bar and slope apron in the Damoguaihe Formation of the Wurhe Depression. Barrier bars distributed in the area of shallow water of lake shore, which are parallel to the lake strandline,and associated with restricted mudstone and coal layers, all together composing of sedi mentary sequences of hundreds of metres thick. Most of barrier sandstones are transgressive-type, characterized by bedding cycles with the sequence of fine-coarse-fine cycles. Slope apron is a type of sandbody newly discovered in Wurxun Dpression, and usually distributed in the onshore-offshore slope environments. It mainly consists of intraclastics and laminated sandstone, interbedded with dark mudstone. The orientation of intraclastics in the area reveals wave action. Slope apron sandbodies spreading parallel to sedimentary slope,are asymetric mound shape along the section in the direction of dip, being steep towards lake shoreline while gently dipping basinward.