Sea level change determined paleochannel development on the continental shelf of the southern East China Sea since MIS 5

Since the late Pleistocene, a large number of paleochannel systems have developed on the shelf of the East China Sea (ECS), and these systems archived important information on sedimentary evolution and environmental changes in the ECS. In this study, we systematically identified the spatial distribution and filling characteristics of the paleochannels in the two stages since Marine Isotope Stage 5 (MIS 5) and investigated the mechanisms on how sea level change responds to paleochannel development and evolution by using sedimentological, geophysical, and chronostratigraphic methods based on high-precision measurements of shallow seismic profiles and borehole data. The results indicate that (1) two stages of paleochannels, named SU2 and SU4 from top to bottom, were identified in the study area in Marine Isotope Stage 2 (MIS 2) and Marine Isotope Stage 4 (MIS 4), respectively; (2) A comparison of the two paleochannel stages reveals that the main stream of SU2 extends longer, than that of SU4; and (3) The paleotopography shows a trend of gradually sloping from the northwestern land area to the southeastern sea area. We conclude that: (1) The sea level fluctuation since the late Pleistocene was the driving force that controlled the development of the paleochannel systems. Understanding this influence can guide the prediction of stratigraphic distribution. (2) The sea level change directly affects the progradation and retreat of coastlines and estuaries, which in turn controls the extension of paleochannels. From this information, the migration range of the coastline can be identified. (3) The SU2 paleochannel may have originated from the Minjiang River, flowed eastward, and merged into the southern tributary of the ancient Yangtze River in the eastern portion of the study area. This study can provide a scientific basis for the southern flow of the MIS 2 ancient Yangtze River system. •Based on high-precision measurements of shallow seismic profiles and borehole data, the spatial distribution and sizes of PCs in two stages (MIS 2 and MIS 4) in the southern CSECS were systematically identified.•Models of sedimentary stratigraphic development in the southern CSECS in MIS 2 and MIS 4 were established, and the study showed that the sea level fluctuations since the Late Pleistocene constituted the key factor controlling the development of the PC system.•This study provides scientific evidence for the southward flow of the paleotributary of the paleo-Yangtze River syst