SEA-LEVEL RISE AND SEDIMENTARY ENVIRONMENT RESPONSE IN THE EAST CHINA CONTINENTAL SHELF SINCE THE LAST GLACIAL MAXIMUM

Up to now, there is no study on large-scale continental shelf system response to global sea level change. In this paper, seafloor sediments in the East China Sea broad continental shelf have been researched in detail by mapping in the past five years. The results show that there is a good response relationship between distribution of modern sedimentary environment in the East China shelf and sea level change since LGM. The seafloor is covered by three sedimentary systems in modern East China shelf, which are ancient onshore zone at the phase of low sea level, transgressive system during the Last Deglaciation and eddy and offshore sedimentary system in the period of high sea level. Three rapid rising periods and slow rising periods could be distinguished after LGM. During the rapid periods, transgressive boundary layer has been formed at seafloor which represents chaotic deposit due to coastal fast-moving. The average moving velocity is 10~22 cm/a (up to 64 cm/a at maximum). In slow rising periods, tidal ridge system which was widely distributed in the continental shelf was formed. There is obvious inheritance and evolution connection among three stages of tidal sand ridge.