【摘要】 通过对舟山群岛表层沉积物样品的粒度分析和黏土矿物含量测定,研究了表层沉积物的粒度分布特征及黏土矿物组成。利用Flemming三角图示法分析了研究区域的沉积动力环境,并探讨了沉积物的物质来源。结果表明,舟山群岛表层沉积物共有5种类型,其中粉砂含量最高,呈片状广泛分布于舟山群岛东部宽阔海域;研究区表层沉积物分选性较差,以正偏为主;沉积物样品在Flemming三角图上投影显示,粉砂沉积物集中在D-Ⅱ,E-Ⅱ,E-Ⅲ区,砂质粉砂等沉积物零星分布在D-Ⅱ,C-Ⅱ及S区,表明研究区沉积物整体粒径较细、岛屿间水动力较强,开阔水域水动力较弱。研究区黏土矿物中伊利石为优势矿物,质量分数均值为61.5%;其次为绿泥石,质量分数均值为15.0%;高岭石和蒙脱石含量较少,质量分数均值分别为12.7%和10.9%。黏土矿物组合类型以伊利石-绿泥石-高岭石-蒙脱石为主,伊利石-绿泥石-蒙脱石-高岭石次之,具有类长江型沉积物特征。舟山群岛表层沉积物以陆源成因为主,物质来源以长江为主、浙江河流入海输沙以及舟山群岛岩石风化产物为补充。更多还原

【Abstract】 Grain-size distribution and clay mineral composition in the surface sediments from the sea areas of Zhoushan Islands are studied through grain-size analysis and clay mineral identification. The sedimentary dynamic environment in the study area is analyzed by means of Flemming triangle diagram and the material sources of the sediments are discussed. The results show that there are five types of surface sediments in the sea areas of Zhoushan Islands, of which silt is the highest in content and is widely distributed in the eastern broad sea area of Zhoushan Islands. The surface sediments in the study area are poorly sorted and dominant with a positive skewness. On the Flemming triangle diagram, silt is mainly concentrated in D-Ⅱ, E-Ⅱ, E-Ⅲ areas and sandy silt is scattered in D-Ⅱ, C-Ⅱ and S areas, indicating that in the study area the overall sediments are relatively fine and the hydrodynamics is strong between the islands and weak in the open waters. Clay minerals in the study area are dominant by illite, with an average content of 61.5%, followed by chlorite, with an average content of 15.0%. Kaolinite and montmorillonite are less in their contents, with the average values being 12.7% and 10.9% respectively. The dominant type of clay mineral assemblage is illite-chlorite-kaolinite-montmorillonite, followed by illite-chlorite-montmorillonite-kaolinite, showing the characteristics of Changjiang-like sediments. The surface sediments in the sea areas of Zhoushan Islands are dominantly terrestrial in origin and their material sources are mainly from the Changjiang River, and then the materials delivered by the rivers in Zhejiang and the weathered rocks in Zhoushan Islands.更多还原