南海中沙海域表层沉积物浮游有孔虫的分布特征及其指示意义

对南海中部中沙海域海底采集的93个表层沉积物样样品进行浮游有孔虫的鉴定分析，获得13属28种浮游有孔虫，依据其中20个主要浮游有孔虫属种的Q型因子分析结果及其抗溶性和生活的气候地带特征，共划分出3个浮游有孔虫组合（占解释总方差的92.3%），包括抗溶性不同的2个热带组合和1个温带-亚热带组合。易溶性的热带组合以Trilobatus sacculifer-Globigerinoides ruber为代表，主要分布于碳酸盐岩台地斜坡区和海岭区。抗溶性热带组合主要以Globorotalia menardii-Pulleniatina obliquiloculata为主，主要分布在中沙海槽和南海深水海盆区。温带-亚热带组合以Globigerina rubescens为代表，主要分布在中沙碳酸盐岩台地北部斜坡区。研究发现，本区浮游有孔虫的分布主要受海水深度控制，而不同温盐性质水团的入侵影响也不容忽视，其中，Globigerina rubescens在中沙碳酸盐岩台地北部斜坡区的富集就是响应研究区以北低温高盐水团的佐证之一。同时，浮游有孔虫的相关分布特征（丰度、简单分异度、碎壳率和易溶种/抗溶种）进一步指示研究区的碳酸钙溶跃面约为2 750 m，碳酸钙补偿深度约为3 400～3 700 m。

Distribution of planktonic foraminifera in surface sediments and its environmental implication in the Zhongsha waters,South China Sea

To understand the planktonic foraminifera distribution and the environmental factors around Zhongsa Islands, South China Sea, 93 surface sediment samples in the area were collected and analyzed. A total of 28 foraminiferal species were identified. Statistical clusters （Q-mode factor analysis） performed to identify three assemblages （92.3% variance） related to modern water masses: two tropical assemblages different in relative dissolution and one assemblage was mainly influenced by subtropical cold water input. The tropical dissolution-susceptible assemblage is dominated by Trilobatus sacculifer and Globigerinoides ruber and mainly buried in the ridge or carbonate slope sediments. The tropical dissolution-resistant assemblage is dominated by Globorotalia menardii and Pulleniatina obliquiloculata, occurring mainly in the deep-water basin or the Zhongsha trough. The subtropical assemblage is dominated by Globigerina rubescens, depositing mainly in the northern slope of the Zhongsha atoll. The distribution of planktonic foraminifera is controlled by the water depth. Moreover, the impact of invasion of water masses with different temperature and salinity is another factor that should not be ignored, as witnessed by the enrichment of Globigerina rubescens in the northern slope sediment of the Zhongsha carbonate platform, which is induced by the northern cold and high-salinity water invasion. Considering the abundance, diversity, and fragmentation of planktonic foraminifera and the variation with water depth, the carbonate lysocline depth and carbonate compensation depth （CCD） are believed to be 2 750 m and 3 400～3 700 m, respectively.