中文摘要：

选择位于青藏高原和云贵高原过渡区的泸沽湖作为研究对象,对南部主湖区70个表层沉积物样品进行了粒度分析,结合湖泊周围自然地理要素,探讨了粒度各组分在空间上的分布特征及其影响因素。结果表明：泸沽湖南部主湖区表层沉积物沉积类型以黏土质粉砂为主,少数样品为砂质粉砂、砂,砾石主要分布在研究区南部和北部湖滨带,其中粉砂是该研究区的优势粒级。另外,南部主湖区表层沉积物粒度各组分分布具有明显的空间差异性,其中研究区东南侧及西南侧由于受入湖河流（山跨河、三家村河）的影响,导致黏土组分呈舌状分别向北、向东北方向延伸,但东南侧由于受湖水外流形成的定向湖流顶托作用,对研究区物源的贡献较弱;研究区西北部砂组分由于受到悬移作用和定向湖流影响,由西北向东南方向凸出;由于受反时针环流作用的影响,大量细粒物质由研究区北部和西南侧悬移至研究区南部并沉积下来,使得此处有大量细物质沉积。同时指出,泸沽湖南湖表层沉积物粒度空间分布的差异性特征受控于湖泊沉积动力过程及沉积物对环境变化响应敏感程度的差异,研究湖泊表层沉积物粒度组成不仅对于认识湖泊水动力及物质输入状况有很大的促进作用,对合理选择钻孔岩芯位置、开展湖泊沉积古气候环境变化研究具有一定的参考意义。

英文摘要：

Lugu Lake is one of the typical plateau-type lakes in the transitional zone between Tibet Plateau and Yunnan-Guizhou Plateau. With relatively weak human impacts,lake Lugu is one of the most suitable lakes for palaoenvironmental study. Based on the grain-size analysis results on 70 surface（ modern） sediment samples in south main lake,combined with the investigation / observation results on the surrounding natural conditions,we have analyzed the spatial distribution features of the different particle compositions and their influential factors controlling the spatial distribution of grain sizes in the Lake. The results show that the grain-size of the samples can be classified into three types,including clayey silt,sand silt and sand. Meanwhile,the grain size components in the studied area have some obvious spatial distribution patterns,for example,the grain size in the east side of the study area controlled by the rivers（ Shankua River and Sanjiacun River） show a obvious tongue-shape mainly composed of clay,and with eastward and northwestward distributions,respectively. Whole in the south part of the study area,the particle distribution pattern is influenced by lake current. In the northwest,the grain-size is dominated by sand because of suspension effect.The lake current carries a lot of sediments from the north and southwest of the study area to the south of the lake and deposit there. Generally speaking,the differences between the grain size distribution patterns are mainly attributed to the lake dynamic processes and the different respond of the sediments to the climate changes. The study on lake surface sediments not only promotes the understanding of the lake dynamics and the status of material input,but also important to select suitable sites to take cores for the paleoclimate-paleoenvironmental reconstruction.