Late Quaternary transgressive and highstand Systems tracts in the northern East China Sea mid-shelf

摘要

Analysis of very high-resolution (3.5 kHz) seismic profiles and sediment data from the northern East China Sea mid-shelf region reveals that the sedimentary sequence above the acoustic basement consists of five late Quaternary sedimentary units comprising transgressive and highstand systems tracts formed after the last glacial maximum. The transgressive systems tract includes four units (1) incised-valley fill (Unit I), (2) transgressive estuarine/deltaic complex (Unit II), (3) transgressive sand sheet (Unit III), and (4) tidal sand ridge (Unit IV). The lower two units (Units I and II), representing a paralic environment, consist of sediment preserved from shoreface erosion. The upper units (Units III and IV), corresponding to a marine environment, consist of sediments produced through shoreface erosion during the Holocene transgression. A ravinement surface separates the lower and the upper units. The highstand systems tract is composed of a distal mud patch (Unit V) derived from the Huanghe and Changjiang rivers in China. Dispersal and deposition of this modern mud are largely controlled by the regional circulation pattern and sediment supply.