Multi-Provenance depositional model of paleo gully in north steep slope of Dongying depression of upper Es4 in Paleogene

Based on seismic reflections and detrital composition analysis as well as cluster analysis, a multi-provenance depositional model of the Upper Fourth Member of the Shahejie Formation was proposed considering the paleo-gully sedimentation controlled by well Y920 in the east of the northern abrupt slope belt in Dongying depression. The result shows that the paleogeomorphology of the Y920 gully develops asymmetrically as abrupt in the west yet gentle in the east during this period. The seismic facies can be divided into two types: the west of the gully is dominated by the wedge-shape reflections, while the east is dominated by progradational reflections. And these two types are separated by the lens-shape reflections in the middle. The detrital composition planar distribution of the sand filling of the gully varies greatly: the west has a low content of quartz and a high content of rock fragment mainly in the type of volcanic; while the east has a relatively high abundance in both the feldspar and the rock fragment mainly in the type of metamorphic detritus; and in the central part the proportions of feldspar and quartz are overwhelming yet the content of detritus mainly in the type of limestone is low. There are three provenances for the Y920 gully including the northern one which provides sediments southward along the long axis and the western and the eastern ones on either side of the gully along the short axis. Thus, the nearshore subaqueous fan and fan delta mainly develop on the west and the east sides respectively.