天山北麓黄土发育特征及形成年代

Character and Age of Loess along North Piedmont of Tianshan Mountains

对天山北麓黄土年代的认识还存在一定分歧。文章在对天山北麓河流阶地进行划分的基础上,通过分析黄土分布与地貌单元(河流阶地与冲积扇)的依附关系,同时结合黄土-古土壤序列分析与ESR测年,初步确定天山北麓地貌面上覆盖的最老黄土年代为0.54 Ma B.P.,这为分析黄土所赋含的环境信息提供时间标尺。

The loess is of importance to understand the progress of environmental evolution in Northwest China, which should be based on the reliable age. Because of the limit of the dating means, the conclusions on the age of loess along the north flank of the Tianshan Mountains are controversial, which makes it difficult to understand the environmental implication of the loess. Loess-paleosol series and the dating method based on the structure of geomorphologie eomplexs make it possible to date the geomorphologie complex and the related deposites. This study aims at giving the age of the loess along the north flank of the Tianshan Mountains. Based on the detailed field work, seven fluvial terraces have been identified along major river channels, and the distribution of loess is thought to be related with these terraces and corresponding alluvial fans. The oldest loess in the north piedmont of the Tianshan Mountains is distributed on the highest terrace T7, and the younger loess on the T6 is more extensive. Loess-paleosol series and the ESR age indicate that the age of the oldest loess in the north piedmont of the Tianshan Mountains is 0.54 Ma.