柴达木盆地东北部哈勒腾河流域风成沉积物粒度特征与空间差异

哈勒腾河流域位于柴达木盆地东北部,是一个近似封闭的内陆盆地。该地区风成沉积物来源相对单一,沙丘类型简单且发育时间短,是研究高原内陆盆地物质迁移规律和风沙地貌发育的理想场所。对115个不同类型、不同地貌部位沉积物粒度进行分析。结果表明:哈勒腾河流域地表沉积类型包括沙丘沙、丘间地沉积、河流沉积和戈壁沉积,主要由细沙组成,平均含量达51.6%。沙丘沙平均粒径1.01~2.90 Φ,分选性较差至极好(0.28~1.74 Φ),频率曲线呈近对称和中等峰态。该流域发育有独特的穹状沙丘,属于新月形沙丘演化的初期阶段,平均粒径1.55~2.54 Φ,分选中等至较好;尽管表现出从迎风坡和背风坡中部到沙丘顶部颗粒变粗、分选变差的特征,但相对同一地区的新月形沙丘而言分选过程较弱。从区域上来看,在W-E走向的断面上,新月形沙丘从西向东颗粒变粗,分选变差;在NW-SE走向的断面上,新月形沙丘由西北至东南颗粒变粗,分选性无明显变化。这表明,该流域风成沉积物的可能物源包括哈勒腾河流冲积物和山前风化剥蚀产物。

Grain size characteristics and spatial variation of aeolian sediments in the Haerteng River,Northeastern Qaidam Basin,China

Haerteng River, located in the northeast of Qaidam Basin, is a near-closed inland basin. The source of aeolian sediments in this area is relatively single with simple dune types and short-term development. Haerteng River is also an ideal place to study the material migration and aeolian geomorphic process in plateau inland basin. The grain size analysis of 115 sediments of different types and geomorphologic positions shows that the surface sedimentary types in this area include dune sand, interdune sediment, fluvial sediment and gobi sediment, which are mainly composed of fine sand with an average content of 51.6%. The mean grain size of the dunes is between 1.01 Φ and 2.90 Φ with the sorting parameters varying from 0.28 Φ to 1.74 Φ. The frequency curve shows a nearly symmetrical skewness and mesokurtic. The distinctive dome dunes, which is the early stage of barchan dunes, have a mean grain size from 1.55 Φ to 2.54 Φ and the sorting is from moderate to relatively good level. Although the characteristics of coarser particles and poorer separation from the middle of the windward and the leeward to the top of dome dunes are shown, the sorting process is weaker than the barchan dunes in the same area. From a regional perspective, the mean grain size of barchan from west to east becomes coarser and the sorting gets worse on the W-E cross section A and it is true of the NW-SE cross section B although the sorting in section B is irregular. The results indicate that the provenances of the aeolian sediments in this area include alluvial deposits of Haerteng River and weathering denudation products of mountains. This study is important for determining the successive relationship between provenances and sediments, exploring the characteristics of the early stage of aeolian geomorphology. Meanwhile, it can provide reference information for regional wind-sand control after the water transfer project from Haerteng River to Dang River.