Sedimentary facies and environmental evolution of the Yangtze shoal, eastern China Sea shelf since Late Pleistocene: Evidence from core YZ05

A 80 m long core, i.e. the Core YZ05, taking from the Yangtze shoal at the inner shelf of Eastern China Sea, is carefully studied by this paper. Although some preliminary results have been published before, it is still necessary to reexamine the interpretation concerning sedimentary facies and the previous models with the newly acquired information. Based on color, grain size, sedimentary texture and structure, contact relationship and fossils, the Late Pleistocene and Holocene succession of the core YZ05 can be classified into ten environmentally significant facies, which include fluvial channel-point bar (F1), overbank (F2), muddy tidal flat (F3), estuary front (F4), tidal sandy ridge (F5), inter-ridge channel(F6), distributary channel bar (F7), distributary channel (F8), distal delta front (F9) and prodelta (F10). Through the analysis of facies association and facies sequences, with the support of Sr/Ba ratios, a retrogradational estuary sequence and a progradational detaic sequence are recognized, which are similar to the post glacial sequences in the Yangtze River delta. AMS¹⁴C and OSL dating suggest that the deposits penetrated by Hole YZ05 are younger than Late Pleistocene. Then the Yangtze Shoal is sourced from the Late Pleistocene deltaic deposits reworked by tidal current.