南海西部表层沉积中的钙质超微化石  

CALCAREOUS NANNOPLANKTON IN SURFACE SEDIMENTS IN THE WEST OF THE SOUTH CHINA SEA

作　　者：陈芳[1] 黄永样[2] 段威武[2] 陆钧[3] 

机构地区：[1]广州海洋地质调查局实验测试所,广州510760 [2]广州海洋地质调查局,广州510075 [3]中国科学院南海海洋研究所,广州510301

出　　处：《海洋地质与第四纪地质》2002年第3期35-40,共6页Marine Geology & Quaternary Geology

摘　　要：分析研究了南海西部 30 8个表层沉积样品中的钙质超微化石 ,发现除一个样品外 ,所有样品均含有钙质超微化石 ,但相对丰度相差悬殊 ,在 0～ 172 5个范围内变化。钙质超微化石在平面上的分布具有较明显的分区性 ,可划分为 3个区。超微化石组合与南海其它地区超微化石组合面貌相似 ,由 15属 2 3种组成 ,以 Gephyrocapsa o-ceanica,G.spp.(small) ,Emiliania huxleyi和 Florisphaera profunda为优势种 ,占 90 %以上 ,其中 Florisphaera pro-funda为绝对优势种。本调查区超微化石的分布受多种因素的综合影响 ,重点讨论了水深、陆源物质的稀释作用、碳酸盐的溶解作用以及重力流的沉积作用等因素对超微化石分布的影响 ,并根据超微化石的分布推断碳酸盐临界补偿深度 (CCr D)约为 310 0 m ,碳酸盐补偿深度 (CCD)大于 4 30 0 m。Calcareous nannofossils analysis has been carried out for 308 surface sediment samples taken from the west of the South China Sea within a wide range of water depth from 36 to 4 245 m.The results show that the relative abundance of calcareous nannofossilis are different among the samples.The highest abundance of calcareous nannofossils is 1 725,but nannofossils are absent just in one sample. The nannofossil assemblages are composed of 15 genera and 23 species,and Gephyrocapsa oceanica, G. spp.(small), Emiliania huxleyi and Florisphaera profunda are most dominant species,and accout for 90% of the assemblage.These assemblages are similar to those in the other parts of the South China Sea.In general, nannofossil abundance decreases with water depth from continental slope to deep water basin. Nannofossil abundance is high in continental slope,lower in continental shelf and deep water basin .The factors controlling the distribution of nannofossils mainly are the dilution of terrigenous material,deep water carbonate dissolution and gravity flow.The CCrD in the west of the South China Sea is about 3 100 m,and the CCD is at least 4 245 m on the basis of nannofossil abundance and CaCO 3 content.

关 键 词：钙质超微化石 表层沉积 南海 丰度 陆源物质 沉积作用 重力流 

分 类 号：P736.22[天文地球—海洋地质]