A CHANNEL-FAN SYSTEM IN NORTHWEST BLOCK OF THE EASTERN DEPRESSION OF THE NORTH YELLOW SEA BASIN

The Neogene sequence in the northwest block of the Eastern Depression of the North Yellow Sea Basin are studied based on high-resolution 3D seismic data, using the coherence and attribution extracting approach. A channel-fan system above the Neogene basal conglomerate is recognized. It was a meandering river system carrying detrital sediments from northwest upon a relatively gentle geomorphology. In the upper reach of the river, the river channel was deeply incised with little lateral migration. In the middle reach of the river, however, the incision was gentle and there was distinctive lateral migration. Point-bars and abandoned channels were well developed. In the lower reach, single channel turned into juxtaposed dual or multiple channels. At the end of the river, it became a kind of sheet flow and formed the deposits similar to a terminal fan. It suggests that the area was exposed to air for a substantial span of time, and changed from proximal alluvial deposits to a distal typical meandering river-fan deposits.