LI Shuai, YANG Shengli, LIANG Minhao, CHENG Ting, CHEN Hui, LIU Nannan

（Key Laboratory of Western China's Environment Systems, College of Earth and Environmental Science, Lanzhou University, Lanzhou 730000, China）

Abstract: The grain size distribution offers information about the potential sediment processes and environmental changes. In order to investigate transportation dynamics and source information contained in the deposit loess in the Eastern Tibetan Plateau, 145 modern topsoil and Malan loess samples from four sub-regions of the Eastern Tibetan Plateau were collected and measured by a Laser Particle Size Analyzer. Nonparametric end member analysis (EMA) and parametric EMA were employed to extract the end members subpopulations from the original grain size data of these samples. Our results showed that: (1) the un-mixing grain size distribution in each sub-region yielded 5 general Weibull distribution end members (1-2 μm, 7-9 μm, 35-45 μm, 60-80 μm and 180-560 μm), representing different material sources and transport processes; (2) the mode, volume ratio and standard deviation of end members in each sub-region were obviously different, indicating that the material composition and proportion of loess in each sub-region were different; (3) the characteristics of end members in the Eastern Tibetan Plateau and in the western margin of the Chinese Loess Plateau were different distinctively, indicating the different source and transport processes across the Eastern Tibetan Plateau.

Keywords: the Tibetan Plateau; loess; grain size; end member analysis

EARTH AND ENVIRONMENT Vol.46, No.4, Tot No.324, 2018, Page 331-338