Holocene microfaunal records in the central Pearl River Delta and implications for palaeoenvironmental changes

Holocene palaeoenvironmental reconstruction was carried out with the data of microfauna (foraminifers and ostracods), AMS¹⁴C dating, sediment grain size distribution, and molluscs, from a borehole drilled in the central Pearl River Delta. During the last glacial maximum, the whole Pearl River mouth was exposed and suffered subaerial weathering, suggested by a layer of extensively distributed mottled clay. A rapid relative sea level rising occurred with the warming of climate during Early Holocene. The marine water intruded into the deltaic area, firstly from the eight south entrances. At about 9010 cal.aBP, marine waters arrived at the central part of the deltaic area. Since then, the study area has become an estuarine environment under water until ~4510 cal.aBP. During the transgression, there were two short-terms of environmental fluctuations recorded by microfauna. The peak of transgression occurred in the time interval from ~7000 to 5630 cal.aBP marked by the highest microfaunal abundance. Since 4510 cal.aBP, however, marine influence weakened and an alluvial plain developed in the central Pearl River Delta area.