湖光岩玛珥湖表层沉积物粒度特征及其物源指示意义

摘要

对湖光岩玛珥湖82个表层沉积物样品进行粒度分析,计算平均粒径、分选系数、偏度和峰度等参数.结果表明:湖光岩玛珥湖表层沉积物主要包括泥、粉砂、砂质粉砂和粉砂质砂4种类型.粉砂和泥在湖内分布范围最广,为主要沉积类型;砂质粉砂和粉砂质砂主要分布在近岸区域,分布范围较小.沉积物平均粒径(Φ值)变化范围2.1~7.5,平均值为6.8,粒度具有由岸向湖随水深增加而逐渐变细的趋势,但在部分近岸区域,由于雨水汇集入湖导致粒度参数变化剧烈.靠近湖岸和火山岩壁,沉积物颗粒最细的区域并未出现在湖水最深处.湖光岩玛珥湖的表层沉积物频率曲线表现为4个明显的组分峰值,尽管沉积物质主要来源为四周火山岩风化产物,但是远距离搬运的细颗粒仍然对沉积物的粒度组分产生较大的影响.%82 surface sediment samples are analyzed and their average values are calculated and sorting, skewness and kurtosis are conducted. The results show that Huguangyan Maar Lake surface sediments are mainly composed of four types of clastics, including mud, silt, sandy silt and silty sand. Among them, silt and mud take up the majority, which are the main sediment type; sandy silt and silty sand are distributed close to inshore region and take up minority. These samples average grain size range from 2.1 to 7.5Φ, with an average value of 6.8Φ. Generally, the grain size of sediment samples becomes finer with increasing of the water depth. However, near the inshore region, the grain size parameter changes dramatically because of the rain wash of the shore into the lake. It appears estuarine deposit trend. The deepest of lake, which is close to the lakeshore and volcanic rock wall, is not the place of the finest sediments region. There are four obviously peaks in frequency curves of the sediments of Huguangyan Maar Lake. Those indicate fine particles transported far away still had a large effect on the size fraction of sediments.