琉球群岛东部海区表层沉积物中浮游有孔虫分布及指示意义

对琉球群岛东部海区123个表层沉积物样品中浮游有孔虫因子分析结果表明,浮游有孔虫组合在溶跃面以上表现为Globigerinoides ruber-Globigerinata glutinata组合,溶跃面以下为Globorotalia inflata-Neoglobo-quadrina pachyderma (dex.)组合,局部受黑潮影响区域黑潮标志种Pulleniatina obliquiloculata含量相对丰富,为Neogloboquadrina dutertrei-P.obliquiloculata组合;表层沉积物中浮游有孔虫的丰度及组合分布特征对于碳酸盐溶跃面深度及碳酸盐补偿深度有一定的指示意义。另外,碳酸盐保存特征研究表明,该区域现代碳酸盐溶跃面深度约为3100 m,碳酸盐补偿深度约为4300 m。

DISTRIBUTION OF PLANKTONIC FORAMINIFERA IN SURFACE SEDIMENTS FROM SEA AREA EAST OF THE RYUKYU ISLANDS AND THEIR INDICATIONS

123 surface sediment samples from sea area east of the Ryukyu Islands were quantitatively analyzed.On the basis of factor analysis for planktonic foraminifera,three faunal assemblages,G.ruber-G.glutinata,G.inflata-N.pachyderma(dex.) and N.dutertrei-P.obliquiloculata assemblages were identified in surface sediments from the study area.It's suggested that assemblage distributions are mainly controlled by carbonate dissolution,and as a result,distribution of G.ruber-G.glutinata assemblage is restricted to sub-area with water depth shallower than carbonate lysocline depth(CLD),but the distribution depth of G.inflata-N.pachyderma(dex.) assemblage is deeper than CLD.N.dutertrei-P.obliquiloculata assemblage is confined to the northwest of the study area due to the existence of overlying Kuroshio Current,and accordingly,the abundance of P.obliquiloculata,a indicator of the above warm current,is obviously high.To some extent,CLD and carbonate compensation depth(CCD) can be indicated by characteristics of abundance and assemblage distributions of the planktonic foraminifera in surface sediments.And it is revealed by carbonate preservation that the present CLD and CCD of the study area are about 3 100 m and 4 300 m respectively.