摘要:
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[1]。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。
Abstract:
Some maincharacteristics of grain-size distribution of sand-gravel 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 sizehistogram，and the sorting of their grain size is m oderately better.The parametervalues of lake-shore gravelsare 81=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 stand-and deviation (81)ranges 0.691-1.854.Saltation and traction populations show theirdo minance in probability curve of grain size of lake-beach sands, w hick indicatesm oderate sorting.Most of the longest axes(a-axes)of lake-shore gravels are parallelto the direction of lake- shore, line,and ab - planes of gravels dip to lake directionat an average angle about 80.It is suggested that the research on the characteristicsof 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 genetictype of ancient lake deposits.
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