中沙群岛附近海域沉积物中的轻矿物分区及物质来源  

Mineral provinces and matter source in surface sediments near the Zhongsha Islands in the South China Sea

作　　者：鄢全树[1] 石学法[2] 王昆山[2] 

机构地区：[1]中国科学院海洋研究所,山东青岛266071 [2]国家海洋局第一海洋研究所海洋沉积与环境地质国家海洋局重点实验室,山东青岛266061

出　　处：《海洋学报》2007年第4期97-104,共8页

基　　金：科技基础性工作和社会公益研究专项资助项目(2003DIB3J114)

摘　　要：海底沉积物中的碎屑矿物（粒级为0．063-0．125mm）的特征及分布样式对于鉴别沉积物的源区具有重要的指示意义．对取自南海中沙群岛附近海域114个表层沉积物样品的轻矿物含量、分布特征和矿物组合进行了研究，在此基础上将本区划分为以下三个矿物组合区：生物碎屑矿物区（Ⅰ）、火山碎屑矿物区（Ⅱ）、混合矿物区（Ⅲ）．生物碎屑矿物区（Ⅰ）的矿物组合单一，为生物骨屑矿物．生物骨屑矿物主要来源于中沙环礁，极少量的陆源物质及火山物质可通过悬浮或风等途径搬运进入此区．火山碎屑矿物区（Ⅱ）的轻矿物以褐色火山玻璃为主，火山渣、无色火山玻璃等火山碎屑矿物含量也较高．风化碎屑及陆源碎屑矿物（如石英等）的含量较低．火山渣在本区呈点源式扩散分布．本区矿物组合为褐色火山玻璃一火山渣．此区的物质来源相对复杂，主要来源于原地海山岩石剥蚀风化以及区内可能存在的正在喷发的小型火山物质的风化，周边岛弧火山对其贡献极小．混合矿物区（Ⅲ）的物源丰富，包括生物源、火山源及陆源，该区又可分为两个矿物亚区：东北部混合矿物区（Ⅲ-1），主要的矿物组合包括生物骨屑矿物、褐色火山玻璃、石英、长石等，陆源物质来自于我国大陆，陆源物质基本上位于17°N以北；东南部混合矿物区（Ⅲ-2），矿物组合为生物骨屑矿物、褐色火山玻璃、石英以及风化碎屑矿物，其中陆源物质可能来自南海南部及西南部大陆中的碎屑矿物，通过发源于大河口的海底峡谷搬运进深海盆．Characteristics and distribution patterns of clastic minerals（0. 063-0. 125 mm in grain diameter） in bottom sediments are a significant indicator for the identification of the origin of sediment. 114 Surface sediment samples, which were collected from the area near the Zhongsha Islands in the South China Sea, were analysed to identify the mineral suites and the their distributions in the study area. The area can be divided into three mineral provinces. Province Ⅰ of biogenic minerals： A mineral assemblage is very simple and is made up of the biogenic detritus minerals, except that the biogenic minerals are mainly originated from the Zhongsha Atoll, a very small quantity of volcanogenic minerals and terrigenous minerals can be transported into this province by means of wind and suspension. Province Ⅱ of volcanogenic mineral： Light minerals in this province mainly include brown volcanic glass, volcanic scoria and colorless volcanic glass; the mineral assemblage in this province is made up of brown volcanic glass and volcanic scoria; the content of weathering detritus and terrigenous minerals is very low; the volcanic scoria in this province takes on distribution pattern from ＂point source＂ diffusion; the material source of this province is relatively complicated; the detrital minerals are mainly derived from local basaltic seamounts and small-scale volcanoes that are probably erupting, with some influences from the island-arc volcanic region around the South China Sea, and island-arc-volcanic regions around this study area have a little influence on modern sedimentation in the study area. Mixed mineral provinceⅢ , in which the material source includes biogenic minerals, volcanogenic minerals and terrigenous minerals. The last province can be subdivided into a mixed mineral sub-province Ⅲ-1 of the northeastern part of the study area, the mineral assemblage mainly includes biogenic detritus minerals, brown volcanic glass, quartz and feldspar, in which terrigenous minerals are mainly derived from C

关 键 词：中沙群岛 轻矿物 矿物分区 物质来源 南海 

分 类 号：P722.7[天文地球—海洋科学] P736.21