Facies Distribution of Borehole DC01 in the West Coastal Plain of Bohai Bay Since MIS3 Using Clayey Water Electric Conductivity and Grain Size Analysis

Abstract

Zhang, L.P.; Fang, J.; Wang, F.; Shang, Z.W.; Li, J.F.; Chen, Y.S., and Tian, L.Z., 2020. Facies distribution of borehole DC01 in the west coastal plain of Bohai Bay since MIS3 using clayey water electric conductivity and grain size analysis. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 795–803. Coconut Creek (Florida), ISSN 0749-0208.To investigate the sedimentary evolution in the West Coastal Plain of the Bohai Bay since Marine Isotope Stage 3 (MIS3), clayey water electric conductivity, grain size, and foraminifera species were measured. According to the AMS14C ages, borehole DC01 was divided into eight units: Unit I (30–29 m), watercourse sediment formed earlier than 46 ka cal BP; Unit II (29–22.4 m), flood plain sediment formed in 45.8 ka cal BP; Unit III (22.4–14.5 m), sediment affected by the storm surge and formed in 45.8–11.2 ka cal BP; Unit IV (14.5–12.6 m), tidal creek sediment representing the rising sea-level in the postglacial period; Unit V (12.6–9.5 m), watercourse-flood plain sediment; Unit VI (9.5–8.34 m), the salt marsh layer affected by seawater that formed during 8.3–7.5 ka cal BP; Unit VII (8.34–3.6 m), watercourse sediment; Unit VIII (3.6–1 m), flood plain with multiple currents that formed in about 3.7 ka cal BP. Studies show that borehole DC01 was affected by seawater twice. (1) The tidal creek sediment and the salt marsh sediment from the postglacial period to 7.5 ka cal BP, which was affected by seawater, represents the rising sea-level and the maximum period of the Holocene MIS1 transgression in the western plain of the Bohai Bay. (2) The storm surge sediment in 45.8 ka cal BP, which was affected by seawater during the MIS3, when the Paleoshorelines were located 20-45 km from borehole DC01.