准噶尔盆地西缘白杨河上游莫合台冲积洪积扇戈壁的特征、时代及过程

Characteristics,age and process of Mohetai alluvial fan gobi in the upper reaches of Baiyang River in the western margin of Junggar Basin,NW China

准噶尔盆地西缘白杨河上游莫合台地区冲积洪积扇戈壁地貌与沉积发育,且富锶水土资源丰富,古环境和水土资源研究意义明显。结合以前研究资料,野外考察和室内分析综合表明:扇群按照形态参数可分为大、中、小3种;扇体基底地层主要由侏罗至新近系下部的倾斜地层组成;扇体地层主要由新近系上部与第四系砾质层组成;扇体地层沉积相主要包括风成亚相(风棱石、沙丘及黄土等)、水成亚相(冲积洪积相、河湖相等)、重力坍塌亚相及疑似冰碛亚相等;扇体主要是在3.596 Ma BP以来形成;地貌与沉积及其环境过程可分为3个阶段7个亚阶段,分别与区域构造-气候阶段相对应。

Gobi geomorphology and sedimentary of the alluvial fan had developed in the Mohetai area,which is located in the upper reaches of Baiyang River in the western margin of Junggar Basin,NW China. There are abundant strontium-rich water and soil resources. It is of great significance to study the paleoenvironment and water and soil resources. Based on previous studies,our field investigation and laboratory analysis,the fan groups were classified into three types by morphological parameter characteristics:large,medium and small.The basement of the fan is mainly composed of dipping strata from Jurassic to the early Neogene. The fan body strata chiefly consist of the upper part of Neogene and the Quaternary gravel layer. The sedimentary facies of the fan body strata include aeolian sub-facies(ventifacts,sand dunes and loess etc.),aquatic sub-facies(fluvial,lacustrine facies etc.),gravity collapse sub-facies and suspected moraine sub-facies. The fan bodies had been primarily formed since 3. 596 Ma BP. The process of geomorphology,sedimentation and environment were divided into three stages and seven sub-stages,corresponding to the regional tectonic-climate stages,respectively.