HOLOCENE FORAMINIFERA FROM THE MUD AREA OF THE INNER SHELF,EAST CHINA SEA AND THEIR PALEOENVIRONMENTAL SIGNIFICANCE

Abstract

The mud area on the inner shelf of the East China Sea is one of the depocenters since the high sea-level of the Holocene.Sedimentary records since the post-glacial saved in this area provide excellent materials for studying paleoceanographic and paleoenvironmental changes during the Holocene.The Core of MZ02 was recovered from the middle of the mud area(121.89°E,28.17°N,water depth 32 m,core length 35.3 m),and radiocarbon dating,grain-size and foraminiferal analyses were performed for paleoceanographic and paleoenvironmental reconstruction.Results show that the environmental evolution in the Holocene can be divided into 4 stages: the stage I was the coastal inner shelf during 10.8~10.5 cal.kaBP;the stage II was the period of the rapid sea-level rise from coastal shelf to the middle shelf during 10.5~8.3 cal.kaBP;the stage III was the inner-middle shelf with the Taiwan Warm Current close to the studied area during 8.3~5.2 cal.kaBP;and the stage IV was the inner shelf under the action of the enhanced coastal current.The abundance of warm-water species increased markedly at 8.4 cal.kaBP,suggesting the invasion of the Taiwan Warm Current since then.The lower δ18O in benthic foraminifera and higher abundance of epifaunal species are thought to be closely related to the enhancement of the coastal current since ~4.0 cal.kaBP.