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三江源区广泛分布着高寒风沙沉积物。野外调查和测验分析了20处风沙沉积物及15处水力侵蚀沉积物的颗粒级配和矿物成分,并整理了21个国内外活动沙丘和63个水力侵蚀和重力侵蚀沉积物的颗粒级配。研究结果表明:风沙沉积物具有均匀的粒径分布和相对固定的粒径大小,完全区别于其他沉积物。活动沙丘演变为固定风沙土的过程中粘土矿物和腐殖质增加:固定风沙土的粘土矿物含量可达到活动沙丘的2倍,而半固定风沙土局于两者之间,固定风沙土的腐殖质含量可达到活动沙丘的3倍左右。粘土矿物和腐殖质的增加导致沙丘表层颗粒细化,固定风沙土的细颗粒含量可达到活动沙丘的2倍左右,分选系数增加近一倍。
Three Rivers source area is widely distributed alpine wind sediments. Field investigation and quizzes analyzed the grain-size distribution and mineral composition of 20 aeolian sediments and 15 hydraulically-eroded sediments, and sorted out 21 active dunes at home and abroad and 63 grain-scale gradients of hydraulically eroded and gravity-eroded sediments. The results show that the sediment has a uniform particle size distribution and a relatively fixed particle size, completely different from other sediments. Clay minerals and humus increase during the process of moving sand dunes into fixed aeolian sandy soil. The content of clay minerals in fixed aeolian sandy soils can reach twice that of active dunes, while the semi-fixed aeolian sandy soils are in between. Reached the activities of sand dunes about 3 times. The increase of clay mineral and humus leads to the grain refinement of the sand dune surface. The fine particle content of fixed aeolian sandy soil can reach about 2 times of that of the active sand dune and the sorting coefficient nearly doubled.