STRATIGRAPHIC SEQUENCE AND DEPOSITIONAL ENVIRONMENT SINCE MARINE ISOTOPE STAGE 6 IN THE CONTINENTAL SHELF OF THE WESTERN SOUTH YELLOW SEA: A CASE OF SYS-0804 CORE

A 65.10-m-long core (SYS-0804) recovered at water depth of 38 m from the relict sediment area off the South Yellow Sea (SYS), together with high resolution shallow seismic profiles, is analyzed on sedimentary characteristics and foraminiferal assemblages. Dated by AMS ¹⁴C and upon the basis of latest research results both at home and abroad, the stratigraphic and environmental evolution and sea level changes during the MIS 6 period are documented in this paper. Results show that the core SYS-0804 can be divided into 6 depositional units, i.e. the DU 1 and the DU4 to DU 8, deposited in the periods of MIS 6, MIS 5, MIS 4, MIS 3 and the early epoch of MIS 1 respectively. The DU 2 and DU 3 formed in MIS 2 and MIS 3 are absent, and the deposits formed in the later period of MIS 1 are also missing. During the period of MIS 6 (128~128 cal.kaBP), fluvial environment (mainly flood plain) dominated the research area. In the early stage of MIS 5 (115~128 cal.kaBP), a nearshore shallow sea environment characterized by cold water mass deposition was prevailing. The depositional units from middle MIS 5 to MIS 4 (60~115 cal.kaBP) are interpreted as the sediments deposited in littoral to inner sublittoral and fluvial environments. The sediments deposited in early to middle MIS 3(40~60 cal.kaBP), show a succession from coastal and shallow sea environments in the early stage, to tidal channels in the later stage. From the later period of MIS 2 to middle MIS 1 (11.5~13.0~0.7 cal.kaBP), it changed into a coast-shallow environment with a transgressional boundary at 11.5~13.0 cal.kaBP. covered by a transgressional sequence formed in the period of sea level rising.