Stratigraphic Development and Sedimentary Environment Evolution in the Bohai Sea Since the Late Pleistocene

Abstract

In recent years, there have been controversies in the evolution of sedimentary environment and stratigraphic division in the Bohai Sea since the Late Pleistocene. Based on the data (lithology, sedimentary structure, micro‐paleontology, and dating data) of 5 boreholes (core of BT113, BT114, BQ1, YRD-1101, and Lz908) in the Bohai Sea, the stratigraphic development and sedimentary environment evolution were revealed in the area since the Late Pleistocene: a marine bed of each borehole in study area was developed during MIS 5 (the MIS 5 bed of core BQ1 is not exposed); during MIS 4, there were fluvial deposits in the cores of BT113, BT114 and BQ1of the study area, but showed be a transitional sedimentary face in cores of YRD-1101 and Lz908,which may be due to the fact that the sea water has not completely withdrawn from the Bohai Sea with short time and temperature decline less than that of the Last Glacial Age. In the early MIS 3, a transgression has been occurred in cores of Lz908, YRD-1101, and BQ1 of the study area, but a fluvial deposit in cores of BT113 and BT114; from the middle and late MIS 3 to the Last Glacial Maximum, the study area was showed a regression during this period; there was have a marine bed due to wide transgression during the Holocene. According to the stratigraphic records of each borehole in the study area, we find that the evolution of the sedimentary environment is consistent with the trend of global sea level changes, indicating that stratigraphic development and the evolution of the sedimentary environment are mainly controlled by global sea level changes in the study area since the Late Pleistocene. In addition, we need further study to find out other factors.