Geochemical Characteristics and Their Implications to Provenance and Environment of Surface Sediments from the South Okinawa Trough
Geochemical Characteristics and Their Implications to Provenance and Environment of Surface Sediments from the South Okinawa Trough
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发表时间：
2002
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通讯作者：
Jiang Fu
中科院分区：
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作者：
Jiang Fu
测定了33个表层沉积物样品的化学组成。样品分别采自陆架、陆坡和冲绳海槽南部。沉积物的化学成分以SiO2、CaO和Al 2 O3为主，约占沉积物总重量的68%。大多数元素在陆棚和陆坡沉积物中变化幅度较大，而在海槽沉积物中基本保持稳定。从陆架到海槽，沉积物粒度变细，SiO2和CaO含量减少，Al 2 O3等大部分元素含量增加。根据常量元素/ Al 2 O3比值的分布，可以认为沉积物是由物源区向海槽迁移的。研究区沉积物主要由陆源沉积、生物沉积和自生沉积组成。通过与长江、黄河沉积物中某些元素的富集因子（EF）比较，可以看出研究区沉积物与长江沉积物具有相似性。Cu、Zn、Pb、Co、Ni、Cr在坡体中的高富集系数是生物富集的结果。Mn的富集是由自生存款引起的。根据化学成分的R型因子分析，结合元素的分布分析，四个主因子分别指示了四种沉积环境。每个沉积区都有自己的典型元素组。它们是：1）陆架型元素组：SiO2、TiO 2、Zr、CaO和Sr，2）斜坡型元素组：Fe 2 O3、MgO和P2 O 5，3）槽型元素组：Al 2 O3、K2 O、Cu、Zn、Co、Ni、Cr和Ba，4）氧化还原型元素组：MnO和FeO。
Chemical compositions of 33 surface sediment samples were measured. The samples were collected from the continental shelf, slope and the south Okinawa Trough, respectively. The major chemical compositions are dominantly composed of SiO 2, CaO and Al 2O 3,which account for about 68 percent weight of the sediments. Most of the elements change with a wide range in the shelf and slope sediments, but keep stable in the trough sediments. From shelf to trough, the grain size of the sediment becomes finer, at the same time, the content of SiO 2 and CaO decrease, and the content of Al 2O 3 and most of other elements increase. Based on the distributions of the major elements/ Al 2O 3 ratio, it can be concluded that the sediments are transported from the provenance area to the trough. The sediments mainly composed of terrigenous, biogenic and autogenetic deposits in the study area. Comparing the enrichment factors ( EF ) of some elements of the shelf sediments with the Yangtse River and Yellow River sediments, It can be concluded that the sediments in the study area are similar to the Yangtse River sediments. The high enrichment factors of Cu, Zn, Pb, Co, Ni and Cr in the slope are caused by the biogenic enrichment. The enrichment of Mn is caused by autogenetic deposit. Based on the R-mode factor analysis of the chemical compositions, combined with analysis of the distributions of the elements, four major factors indicate four sedimentary environments respectively. Every sedimentary area has its own typical elements group. They are, 1)Shelf type elements group:SiO 2,TiO 2,Zr,CaO and Sr; 2)Slope type elements group: Fe 2O 3,MgO and P 2O 5; 3)Trough type elements group:Al 2O 3, K 2O, Cu, Zn, Co, Ni, Cr and Ba, and 4)Redox elements group:MnO and FeO respectively.