QUATERNARY TRANSGRESSIONS AND COASTLINECHANGES IN HUANGHE RIVER(YELLOW RIVER) DELTA
Yang Huairen Wang Jian (Nanjing University, Nanjing, China, 210008)
Based on studies of biostratigraphy, magnetostratigraphy, lithostratigrapfay, ground-water chemistry and salinity of Quaternary sediments in the Huanghe River (Yellow River) Delta, Quaternary marine transgressions and their characteristics have been demonstrated. It is found that the sea transgressed into the delta land for twelve times during the past three million years. According to magnetostratigraphy, radiocarbon data and sedimentation rate, the transgressions are estimated to have happened during 3.00 Ma. B. P., 2.23-2.20 Ma. B.P., 1.57-1.50 Ma.B.P., 1.27-1.17 Ma.B.R, 0.60-0.50 Ma. B. P., 0.40-0.30 Ma.B.P., 0.25-0.20 Ma.B.P., 0.18-0.15 Ma.B.P., 0.12-0.10 Ma.B.P., 0.09-0.07Ma. B. P., 0.04-0.025 Ma.B.P., and 8,000-4,000 a.B.P. respectively. Average rate of tectonic subsidence in Brunhes was about two times that in Matsuyama in the delta. Because of the accelerating of tectonic subsidence, marine transgression occurred more frequently and exerted greater effects on the Huanghe River Delta in Brunhes than in Matsuyama. As a result of that, salt ground water has a larger distribution in the upper Quaternary than in the lower. The coastline at the maxiumum of Holocene transgression is also drawn through analysis of a hundred cores. At that time, the coastline was 80-100 kilometers more landward in the Huanghe River (Yellow River) Delta.