罗布泊地区红柳沙包纹层沙粒度特征与环境指示意义

通过对罗布泊西南缘一个红柳沙包的132个清晰沉积纹层沙物质特征分析表明:所有沉积纹层沙物质均以细砂为主,占42.54～91.82%,其中1871-1874年纹层砂粒最细,1903-1910年纹层砂粒最粗;沙物质粒径分布在0.044～0.283mm之间,平均值0.095mm,中值粒径0.083mm;所有纹层沙物质的分选性都很好,分选系数分布在0.04～0.06之间,平均值0.05;偏态值分布在0.14～0.35之间,平均值0.19;峰态值分布在1.03～1.17之间,平均值1.13;沙物质粒度分维值分布在1.39～2.88之间,平均值2.80。除沙层厚度外,粒级组成、粒度特征参数、粒级分布曲线以及粒度累计概率曲线等也有较明确的环境指示意义。

Grain-size features of sand materials in Tamarix cone veins and theirs environmental indication significance in the Lop Nur region

Through analysis of sandy material sediment sampling from a Tamarix cone with 132 clear sedimentary veins located at the west shore of Lop Nur,the research results are obtained as follows:all of the sandy materials of sedimentary veins in studied section mainly consist of the fine sand that occupies 42.54%-91.82%,among which the finest grained sand was deposited in the period of 1871-1874,and the coarsest one was deposited in the period of 1903-1910.The grain sizes of sandy materials in every sedimentary vein are distributed in the range of 0.044-0.283mm diameter,the average is 0.095 mm,and the median grain size is 0.083 mm.The sorting of sandy materials in every sedimentary vein is very good.The coefficients are within the scope of 0.04-0.06,the average is 0.05.The distribution range of Skewness is 0.04-0.06,the average is 0.19.The distribution range of Kurtosis is 1.03-1.17,the average is 1.13.The distribution range of fractal dimension value of sandy materials is 1.39-2.28,the average is 2.80.Besides of the sedimentary thickness of sandy materials,the grain-size composition,parameter of grain-size characteristics,grain-size distributed curve as well as accumulated probability curve have more clear environmental indication significance.