三峡水库干流沉积物的粒度分布与矿物组成特征

研究表明:三峡库区干流沉积物的粒度分布和矿物组成都呈现以奉节为界的区域性.库区干流沉积物的岩性为粘土质粉砂,粉砂的平均含量为61%,属于单众数,反映了库区各点的水体流速变化幅度不大.沉积物的主要矿物成分为绿泥石、伊利石和石英,平均占29%,24%、24%;其次为长石、方解石和白云石,占8%、9%、5%;其余为少量的闪石和黄铁矿.与过去相比,库区干流沉积物的矿物组成结构发生很大改变:石英的含量降低将近一半,绿泥石和伊利石的含量大幅度增加.这增加了三峡水库发生富营养化和其它环境问题的潜在风险.

Distributional Characteristics of Grain Size and Mineral Composition in Sediments of Yangtze River in Three Gorges Reservoir

The results show that： The distrbutional of grain size and mineral composition in the sediments of the Yangtze River in Three Gorges Reservoir present defferent regional characteristics and Fengjie is the dividing point.The lithology of the sediments is clayey silt while the percentage of silts is 61% with single mode grain distribution.It reflects that the flow velocity of the Yangtze River remained relatively stable.The sediments are dominated by chlorite（29%）,illite（24%） and quartz（24%）,the rest mineral components is feldspar（8%）,calcite（9%）,dolomite（5%） as well as a little of amphibole and pyrite.Compared with the past,the structure of mineral composition changed significantly;the quartz content reduced by half while the content of chlorite and illite has increased greatly;and that will enhance the potential risks of the eutrophication and other environmental issues of the Three Gorges Reservoir.