南沙海区晚第四纪浮游有孔虫演化及其古海洋学意义

通过对南沙海区17957和17958两柱状样中浮游有孔虫的研究，首次揭示了南海晚第四纪以来较长时间尺度上（0－800ka BP)存在δ18O 11期（约400ka BP)开始的粉红色Globigerinoides ruber大量出现和Globigerina rubescens较高相对丰度，δ18O 5e期（约120ka BP)的粉红色Gl9obigerinoides ruber 绝灭，Globoquadrina Conglomersata大量出现，Globorotalia truncatulinoides 左旋型分子绝对优势开始，和δ18O 4／5期界线附近（约80ka BP)的Globo quadrina conglomerata绝灭等三次浮游有孔虫演化事件，南沙与南海北部及西北太平洋等海区的浮游有孔虫演化事件对比 表明，南沙海区在400ka BP开始海水温跃层相对较深，至δ^18O 5e期时，受西北太平洋中层水加强的影响，南沙海水温跃层变浅，在δ^18O 5e至4／5期界线这段时期内与西北太平洋水体交换比较自由。

LATE QUATERNARY EVOLUTION OF PLANKTONIC FORAMINIFERA IN THE SOUTHERN SOUTH CHINA SEA AND THEIR PALEOCEANOGRAPHIC SIGNIFICANCE

For the first time in the southern South China Sea, a long sequence of deep sea sediment has been disclosed in two sedimentary corse (17957 and 17958) for the reconstruction of the paleoceanographic history. Based on the evidence of planktonic foraminifera, there existed at least three bio events during the last 800 000 years: First, the pink pigmented Globigerinoides ruber appeared and Globigerina rubescens became abundant at the oxygen isotopic stage 11 (around 400 ka BP); Second, pink pigmented Globigerinoides ruber disappeared, Globoquadrina conglomerata came out, right coiled Globorotalia truncatulinoides began to dominate in these cores at the isotopic stage 5e(120 ka BP); and finally, Globorotalia truncatulinoides disappeared at the boundary of isotopic stages 4 and 5 (80 ka BP). The evolution of planktonic foraminifera from the southern South China Sea implies that the sea surface water became warmer or the thermocline became deeper during the period between 400 and 120 ka BP, and the exchange of water masses between the South China Sea and the West Pacific is relatively free during 120-80 ka BP because of the stronger influence of the West Pacific Intermediate Water.