EROTION ON THE SOUTHERN YELLOW SEA BED

Around 300 bottom samples were collected from the southern Yellow Sea (SYS) and the northern East China Sea (ECS) in May, 1992 to Oct, 1993 using an Ocean-50 grab sampler, a piston core and a benthonic trawl. Analyses were conducted on the grain-size, mineral and biological assemblages and stratum chronology. The results using sediment gtain-size parameters show that the depositional environment on the continental shelves of the SYS and the northern ECS were very complex. Sandy sediments and Tertiary sandstone and / or gravels occured extensively on the SYS shelf. It is found that the sandy sediment contain the Tertiary sporopollen and glaucanite, without marine facies dinoflagellates. These characteristics reveal that the sandy sediment has a close relationship with the Tertiary sandstone and/or gravel containing glaucanite. The area of sandy sediment distribution is associated with strong tidal currents and storm. Under the influence of these hydrodyndrical elements fine sediments should be suspended and removed from the area gradual, coarsening of original sediment occurs. The findings were as follows: 1) the sandy sediment were formed in response to erosion and reworking of previous sediments in high energy environments; 2)the presence of the Tertiart sporopollen and glaucanite suggests that the sandy sediment is relared to the Tertiary sandstone and gravel, the sandy sediments are derived from the weathering of the old deposit, 3) the sandy sediment containing late Pleistocene shell and antler reveals thes deposit was formed before the Holocene trensgression. Therefore, the sandy sediment is an important part of the strata, with significance in the study on sediment dynamics in the southern Yellow Sea shelf.