【摘要】 <正> 哈拉湖盆地是祁连山西部的一个山间盆地。哈拉湖位于盆地中心,属高山内陆湖泊。湖面海拔高度4077米,最大水深65米,平均274米。湖泊呈北西西—南东东延伸,长32公里,平均宽度13公里,面积为580平方公里。哈拉湖盆地北部有疏勒南山巍峙,海拔在5000米以上,南为哈拉湖南山,平均海拔不到5000米。盆地东西两侧的分水岭均系低平的丘陵地带。南北二山由上泥盆统、石炭系和三叠系地层组成,盆地内部除零星出露第三纪地层外,余为第四系洪积、冰水冲积物覆盖。更多还原

【Abstract】 Some main characteristics of grain-size distribution of sand梘ravel sediments have been presented in this paper through the grain-size analysis of Halahu lake-shore sediments. Most of the lake-shore sediments are of unimodal form in size histogram, and the sorting of their grain size is moderately better. The parameter values of lake-shore gravels are δ1 = 0.462-0.935, SK1 = -0.169-+0.134, Kg = 0.961-1.414. The skewness(SK1) of lake-beach sands is predominately negative, and their standard deviation (δ1)ranges 0.691-1.854.Saltation and traction populations show their dominance in probability curve of grain size of lake-beach sands, which indicates moderate sorting.Most of the longest axes(a-axes)of lake-shore gravels are parallel to the direction of lake-shore, line,and ab-planes of gravels dip to lake direction at an average angle about 8°. It is suggested that the research on the characteristics of grain size distribution of lake-shore sand-gravel sediments be of great import-ante to the study of sedimentary environment and the identification of the genetic type of ancient lake deposits.更多还原