辽东湾表层沉积物碎屑矿物组合分布及其对物源和沉积物扩散的指示意义

Detrital mineral assemblages and distributions as indicators of provenance and dispersal pattern in surface sediments from Liaodong Bay,Bohai Sea

对取自渤海辽东湾的128个表层沉积物样品进行了碎屑矿物鉴定,对矿物成分含量应用log-ratio法处理后进行统计分析。结果表明,研究区重矿物质量百分含量平均值为6.3%,高值区位于六股河口和湾西北近岸。共鉴定出7种轻矿物,38种重矿物,轻矿物以石英、斜长石和钾长石为主,重矿物以普通角闪石、绿帘石、磁铁矿、石榴子石、钛铁矿为主。根据碎屑矿物的组合分布特征,可将研究区划分为两个矿物组合区,其中又可细分为6个矿物亚区。六股河和湾西北近岸矿物亚区的碎屑矿物主要来源于六股河、湾西北入海小溪和海岸侵蚀物质,湾东北部矿物亚区沉积物主要来源于双台子河和大辽河,湾中部矿物亚区为多源混合区,湾南部矿物亚区受邻近海域和复州河沉积物影响大,湾东南部的辽东浅滩矿物亚区为潮流作用的产物。与河流入海沉积物相比,该区表层沉积物的石英/长石比值和ZTR指数明显增大。研究认为,物源是控制研究区碎屑矿物的组合与分布的主要因素,同时也受到海洋水动力和矿物性质等因素影响。

In the present paper ,we investigated the detrital mineral composition ,assemblage and distribution in surface sediments from Liaodong Bay （LDB） ,Bohai Sea. The log-ratio method was used to represent mineral com-positional data for the multiple statistical analysis. Heavy mineral weight percentage is 6.3% on average ,and the high value areas are located at Liuguhe river mouth and nearshore zone of northwestern coast. A total of 7 species of light mineral and 38 species of heavy minerals were identified by using the classical microscopic method. Light minerals are dominated in quartz ,plagioclase and K-feldspar ;w hilst heavy minerals are mainly composed of horn-blende ,epidote ,magnetite ,garnet ,ilmenite ,titanite ,actinolite ,limonite ,hematite ,apatite and augite. The LDB could be divided into 2 detrital mineral provinces ,including 6 sub-provinces ,according to the detrital mineral as-semblages and their distribution pattern. Sediments in Liuguhe river mouth and nearshore zone of northwestern coast are mainly derived from Liuguhe river ,small streams flowing into the northwestern LDB and coastal erosion ;sediments in northern LDB are mainly originated from Shuangtaizihe river and Daliaohe river ;central LDB province is a multi-source depositional area ;sediments in southern LDB are mainly affected by adjacent sea and Fuzhouhe river;sediments in Liaodong Shoal province ,w hich is located in southeastern LDB ,may be dramatically reformed by tidal current. Compared to sediments from rivers around LDB ,quartz/feldspar ratio and ZTR index of surface sediments show an increasing trend. Assemblages and distribution pattern of detrital minerals in the bay are mainly controlled by provenances ,and also affected by hydrodynamic and grain density.