THE CHARACTERISTICS ANALYSIS OF SEA BOTTOM DEPOSIT IN LINGDINGYANG BAY OF THE PEARL RIVER ESTUARY

The geo-environment along the coast of the Pearl River estuary is very sensitive as the area lies in the interacting zone between ocean and land. It will be very useful for sustainable development of regional exploitation and construction if understanding the characteristics of sea bottom deposit in Lingdingyang Bay. Based on the fore-researches of shoals, troughs, seabed topography and sediments etc, Guangzhou Marine Geological Survey (GMGS) carried out the project (1:100 000) of marine geo-environment and geo-hazards survey in the Pearl River delta between 2003 and 2005, and then analyzed the deposit characteristics of Lingdingyang. After the integration of the data of geophysics, seabed sediments and strata from soil samplings and drilling cores, the result is that the seabed sediments'of Lingdingyang have 6 types, sand, silty sand, sand-silt-clay, sandy clay, clayey silt, and silty clay. The sea bottom deposits of Lingdingyang since late Pleistocene consist of two stratal groups. Stratal A is the transgressive sediments since Hol-ocene. The sediments are mainly silty sand and sand-silt-silty clay in accordance with drilling cores. Stratal B is mainly the sediments of terrestrial deposit and denudation, with some as marine-terrigenous facies. The sediments are mainly clayey silt, fine sand-coarse sand with gravel and silty clay-clay since late Pleistocene. It is the demorphism of rock and bedrock below stratal B.