地理学报 ›› 2010, Vol. 65 ›› Issue (1): 53-64.doi: 10.11821/xb201001006

• 地貌与第四纪 • 上一篇    下一篇

库姆塔格沙漠地表物质组成、来源和风化过程

徐志伟1, 鹿化煜1, 赵存法1, 王先彦1, 苏志珠2, 王振亭3, 刘宏宜4, 王立新1, 卢琦2   

  1. 1. 南京大学地理与海洋科学学院, 南京210093;
    2. 中国林业科学研究院荒漠化研究所, 北京100091;
    3. 兰州大学资源环境学院, 兰州730000;
    4. 中国气象局兰州干旱气象研究所, 兰州730020
  • 收稿日期:2009-08-10 修回日期:2009-10-03 出版日期:2010-01-25 发布日期:2010-03-31
  • 通讯作者: 鹿化煜(1968-), 男,教授, 从事第四纪环境变化和自然地理学教学与研究工作. E-mail: huayulu@nju.edu.cn
  • 作者简介:徐志伟(1988-), 男, 研究生, 从事自然地理学的学习和研究. E-mail: x-nju@163.com
  • 基金资助:

    国家科技基础性工作专项(2006FY110800); 国家大学生创新训练计划项目(081028413); 国家自然科学基金项目(40930103) 联合资助

Composition,Origin and Weathering Process of Surface Sediment in Kumtagh Desert,Northwest China

XU Zhiwei1; LU Huayu1; ZHAO Cunfa1; WANG Xianyan1; SU Zhizhu2; WANG Zhenting3; LIU Hongyi4; WANG Lixin1; LU Qi2   

  1. 1.School of Geographic and Oceanographic Sciences; Nanjing University; Nanjing 210093; China; 
    2.Institute of Desertification Studies; Chinese Academy of Forestry; Beijing 100091; China; 
    3.College of Earth and Environmental Sciences; Lanzhou University; Lanzhou 730000; China; 
    4.Lanzhou Institute of Arid Meteorology; China Meteorological Administration; Lanzhou 730020; China
  • Received:2009-08-10 Revised:2009-10-03 Online:2010-01-25 Published:2010-03-31
  • Supported by:

    China National S&T Basic Work Program, No.2006FY110800; National Undergraduate Innovation Program, No.081028413; National Natural Science Foundation of China, No.40930103]

摘要:

通过对库姆塔格沙漠地表沉积物样品进行重矿物和主量元素分析,获得了其矿物和元素组成特征:矿物种类多,绿帘石和角闪石含量为主;化学组成上以Si、Al为主,和上陆壳平均化学组成相比,除Si、Ca外都有一定的亏损,Fe、Mg、Ca、P、Ti、Mn等元素的变异系数较高。库姆塔格沙漠地表沙物质组成特征与阿尔金山北麓出露的岩石和冲、洪积扇物质组成基本一致,与塔克拉玛干沙漠也有很大的共性,反映了库姆塔格沙漠地表沙物质主要来源于阿尔金山。沙漠北区强烈的东北风将阿奇克谷地和疏勒河下游的河湖相沉积物搬运至沙漠腹地,构成另一个重要的沙物质来源。A-CN-K图解揭示了库姆塔格沙漠地表物质化学风化程度很低,处于较弱的去Na、Ca阶段,其他元素未发生明显的化学风化或迁移;A-CNK-FM图解表明,库姆塔格沙漠地表物质在搬运、沉积过程中Fe、Mg等元素发生显著分异,其原因主要是铁镁质矿物由于磨损、分选作用遭破碎和风化,使粒度较粗的沙漠沙Fe、Mg等元素相对亏损。

关键词: 矿物, 地球化学元素, 物源, 风化过程, 库姆塔格沙漠

Abstract:

The Kumtagh Desert is one of the eight biggest deserts in China.In this study,33 representative surface sediment samples were collected from Kumtagh Desert and analyzed in the laboratory to obtain composition of heavy mineral and content of geochemical elements.Results show that there are various kinds of heavy minerals in these samples,with large content of epidote and hornblende.Si and Al take up a large part of chemical composition.Compared with the average composition of geochemical elements of the upper continental crust(UCC),all elements except Si and Ca are depleted to a certain degree;Fe,Mg,Ca,P,Ti and Mn have high coefficients in their contents.Mineral composition of the samples of the Kumtagh Desert has a similarity with that of rocks of Altyn Tagh,surface sediments of the alluvial/fluvial fans of the Aityn Tagh and that of the Taklamakan Desert,indicating that one major source of the Kumtagh Desert sediments is located in Altyn Tagh.Alluvial deposits and lake sediments in Aqik valley and lower reaches of the Sule River are prone to be eroded and transported by the strong northeasterly wind to the Kumtagh Desert,as a result these places form another source of surface deposits of the Kumtagh Desert.A-CN-K ternary diagram shows that a weak chemical weathering by loss of Na and K occurred in these sediments,while other geochemical elements was in a less weathering or leaching process.A-CNK-FM ternary diagram suggests that Fe and Mg have distinct chemical differentiation.Physical weathering process makes it easy for mafic minerals to be eroded and enriched in fine particles,thus coarse desert sand particles can be relatively depleted in Fe and Mg.Mineral and geochemical composition of sediments in arid regions with less chemical weathering are mostly effected by physical processes.

Key words: minerals, geochemical elements, sediments provenance, weathering process, Kumtagh Desert

中图分类号: 

  • P931.3