中文摘要：

以南海南部86GC沉积物柱状样为研究对象,通过对浮游有孔虫氧、碳同位素组成和AMS14C测年的研究,初步确定该柱状样包含了氧同位素3期晚期以来约31 400 a的沉积。结合浮游有孔虫组合和沉积物地球化学记录,分析认为,研究区域末次盛冰期发生于大约29~19 kaBP,其中又以28~26 kaBP为顶峰时段;在大约21~20 kaBP之间,可能有过一次短暂的海平面快速上升事件。单从δ18O记录来看,全新世南海南部的气候和古海洋环境似乎保持着较为稳定的状态,但期间δ13C及其他一些古气候指标却记录了多次回返性事件,反映出由于冬季风的短暂加强,导致全新世该区域气候环境在总体适宜的背景下仍然具有不稳定性。

英文摘要：

The column sample of 86GC recovered from the southern South China Sea was analyzed in order to reveal the paleoenvironmental evolution.Mainly based on the stable oxygen and carbon isotopic records of planktonic foraminifera and AMS 14C dating,the stratiqraphy of the sediment sequence was preliminarily constructed.It suggests that the calumn represents the deposifs formed since ca.31 400 BP in the late period of Marine Oxygen Isotope Stage 3（MIS 3）.The last glacial maximum（LGM） in this area began at ca.29 kaBP and ended at ca.19 kaBP.The worst condition occurred in the early part（ca.26~28 kaBP） which is defined as the peak of the LGM.It is likely that a sudden and short sea level rise event happened during ca.21~20 kaBP The δ18O records show that the climate and oceanography were comparatively stable during the Holocene,but both the δ13C and some other paleoclimatic proxies are rather complicated,including several times of short abrupt reversals,suggesting the instability of environment in Holocene due to briefly enhanced northeast winter monsoon.