黄土高原西部地区黄土粒度的环境指示意义  

Environmental Significance of Grain Size of Loess-paleosol Sequence in Western Part of Chinese Loess Plateau

作　　者：汪海斌[1] 陈发虎[1] 张家武[1] 

机构地区：[1]兰州大学资源环境学院,甘肃兰州730000

出　　处：《中国沙漠》2002年第1期21-26,共6页Journal of Desert Research

基　　金：教育部重点项目(99113);自然科学基金项目(49871072)资助

摘　　要：通常把＞３０　μｍ颗粒含量作为冬季风的替代指标。对黄土高原西部地区的兰州九州台剖面、西宁土巷道剖面粒度主成分和聚类分析表明：　＞４０　μｍ颗粒的含量是黄土高原西部地区更为敏感的古冬季风替代指标，　＜２　μｍ颗粒的含量的变化所指示的古气候意义可能与黄土高原中部地区不同。Chinese loess paleosol sequence has provided some the most detailed terrestrial records of climate changes in Quaternary. Grain size and magnetic susceptibility have proved to be good proxies of East Asian Winter Monsoon and Summer Monsoon variations respectively. Studies on loess sections through Loess Plateau in Central China suggested that >30 μm size fraction is a sensitive proxy of winter monsoon strength for central part of loess plateau. However, one thing that should be reemphasized is that grain size distribution becomes finer leeward, from northwest through southeast, gradually on Chinese Loess Plateau. Therefore >30 μm size fraction should be argued when it was issued as an indicator of winter monsoon strength of west Chinese Loess Plateau. While western part of Chinese Loess Plateau has great potentials to provide much higher-resolution climatic records than Central Chinese Loess Plateau does. So it is necessary to find out a sensitive proxy of winter monsoon strength for West Chinese Loess Plateau. This paper focuses on discussing grain size distribution characteristics of two typical loess sections, Tuxiangdao Section in Xining and Jiuzhoutai Section in Lanzhou, on West Chinese Loess Plateau so as to obtain related climatic information and appropriate proxy of winter monsoon strength. Using SPSS for Window 8.0, we conduct Principal Component Analysis on amounts of size distribution data of these two Loess sections. Output accomplished with SPSS shows that the cumulative loading of the initial three components of Jiuzhoutai section and Tuxiangdao section accounts for 95.37%, 96.07% respectively, which suggests that these three extracted principal components are fully credible. Results also indicate that the first component and the third component is linked to winter monsoon variation in Jiuzhoutai section; while the first component and the second component is related to winter monsoon variation in Tuxiangdao section. To determine candidate for winter monsoon strength proxy, we employ classifying a

关 键 词：风尘 冬季风 古气候 主成分分析 黄土高原 黄土粒度 

分 类 号：P642.131[天文地球—工程地质学] P532[天文地球—地质矿产勘探]