SEDIMENTARY ENVIRONMENTAL EVOLUTION OF MUD AREA OFF THE SOUTHERN COAST OF WEIHAI SINCE LATE PLEISTOCENE

Three stages of evolution are recognized since Late Pleistocene based on the data of grain size analysis, AMS¹⁴C dating, OSL dating of the shallow drilling hole (WHZK01) 25.1m long from the muddy area in the southern Weihai coast, in combination with the seismic stratigraphy and other drilling cores nearby. 1) The fluvial facies (late MIS3) formed in a turbulent and unstable strong dynamic environment; 2) The flood plain and estuarine facies (early MIS1) formed in a weak dynamic environment; 3) The nearshore and shallow marine facies formed in a weak and stable environment. The sea level change since Late Pleistocene is the major factor controlling the sedimentary evolution of the study area. When the sea level rose to the highest level in the Middle Holocene, the modern Yellow Sea circulation patterns began to establish with the formation of the Yellow Sea warm current. Under the control of the Yellow Sea coast flow, the sediments were transported to the study area from Huanghe River bypassing through the Chenshan Head and thus the mud area was formed quickly off the southern coast of Weihai.