现代珠江三角洲地区晚第四纪海侵的微体古生物记录

海平面波动历史对认识低海拔海岸带地区地质环境演化具有重要的参考意义。在年代测试的基础上,结合岩芯的沉积特征,通过对现代珠江三角洲地区QZK1和QZK4孔微体古生物化石的鉴定分析,发现有孔虫和介形类微体古生物化石均仅出现于两孔全新统的灰色粘土层中。微体化石分布特征显示:现代珠江三角洲地区全新世海侵从早全新世,或稍早的晚更新世开始,而QZK4孔620cm附近可能记录了全新世海平面的最高值,之后海平面开始下降至现代高度;前人报道的晚更新世海侵发生时间内,两孔中发育陆相地层,未发现海侵沉积。

MICROPALEONTOLOGICAL RECORDS OF LATE QUATERNARY TRANSGRESSION IN THE MODERN PEARL RIVER DELTA REGION,GUANGDONG PROVINCE,S.CHINA

The history of sea level fluctuations is critical for understanding the evolution of geological environment in the low altitude coastal area.Based on the AMS and OSR datings and the sediment characteristics,the faunal microfossils are analyzed in sediments from the cores QZK1 and QZK4in the modern Pearl River Delta(PRD)region.The microfossils of foraminifera and ostracoda are only found in the Holocene gray-clay layers.The distribution patterns of the faunal microfossils indicate that the Holocene transgression began at the early Holocene or a bit earlier—the late Pleistocene,and the sediment at depth~620cm in the Core QZK4 possibly recorded the highest sea level during the Holocene in the modern PRD region,then the sea level fell to recent level;However,during the time for the previously reported late Pleistocene transgression,only terrestrial strata revealed in the two cores and there was no transgression layers been recognized.