Incised-valley Sedimentary Succession and Evolution of the Nanjing Section of the Yangtze River since the LGM

Li, Y.Y. and Wang, J., 2020. Incised-valley sedimentary succession and evolution of the Nanjing section of the Yangtze River since the LGM. 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. 785–794. Coconut Creek (Florida), ISSN 0749-0208.The incised valley at the Nanjing section of the Yangtze River contains a detailed sedimentary succession since the last glacial maximum (LGM). As stratigraphic and chronologic frameworks are not available for the Yangtze at the Nanjing section, five cross sections were constructed from 230 boreholes. Twenty-five radiocarbon and five ESR ages provided a detailed chronological framework. Based on analysis of lithology and sedimentary architecture, six deposition units were divided. The two main stages included the deep cutting stage from 23,000 to 15,000 cal yr BP and the lateral developing stage from 15,000 cal yr BP to the present. During the deep cutting stage, relative sea level change was the primary factor determining incised valley evolution. The great gradient provided a powerful hydrodynamic condition for palaeochannel cutting into the bedrock and large pebble gravel deposition. The faults and injection of the tributaries resulted in an incised depth deeper than the upstream and downstream. During the lateral developing stage, with the rapid rise of sea level and the moister and warmer climate, the incision power decreased and the channel broadened, resulting in a gradual reduction of sediment size.