河西走廊地区地表沉积物地球化学示踪-1.doc

河西走廊地区地表沉积物地球化学示踪
王立强*基金项目:国家自然科学基金项目(批注号:40721061,40671192)、教育部“新世纪优秀人才支持计划”与“111计划”资助
作者简介:王立强(1984-),男,硕士研究生,地球化学勘查专业。Email: wanglqiang08@
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广东省第五地质大队肇庆 526000
中文摘要
本文对河西走廊地区的巴丹吉林沙漠与腾格里沙漠、戈壁滩、黑河与石羊河河流平原以及祁连山坡麓4种类型的地表沉积单元进行地表采样,并对其全样和<38 μm细颗粒组分的粒度组成和元素含量等指标进行测量与分析,得出结论:全样存在粒度和常量元素的端元分布,沙漠和祁连山为差异性最大的端元,而河流平原与戈壁滩分布在两个端元之间;但四者全样、细颗粒组分以及黄土的微量元素分配特征以及FD端元分布曲线表明四者并无太大区别;同时粉尘在源区经历了一定程度的混合作用,而能够搬运至下风向的细颗粒成分在源区经历了脱Ca、Na等的初等化学风化,并且该区的山前洪积扇、河流堆积、沙漠与下风向粉尘堆积存在着密切的物质联系,高山作用过程起着主导作用。
关键词:粉尘源区,地表沉积,元素含量,粒度组成
Abstract
In this study, we have sampled four types of surface deposits in the Hexi Corridor and its adjacent regions, including Badain Jaran Desert and Tengger Desert, the Gobi deserts, the flood plains of Shiyanghe River and Heihe River, and the deposits at the piedmont of Qilian Mountains (including loessic deposits). Based on the results of particle size and positions of the bulk samples and < 38μm grain sizes, and major positions ic susceptibilities of the bulk samples in the regions exhibits an evident end-member pattern, . the deposits at the piedmont of Qilian Mountains and the sandy desert. The deposits of river plains and gobi desert fall into the range of the end-members. However, there is no distict difference in the trace positions of the different deposits. Meanwhile, the strong winds in desert regions blow light minerals leeward, resulting in the lowest ic susceptibility in the bulk desert samples and the highest values in the fine-ponent of desert the background of global cooling, the loose debris of the study area has undergone intensive deflation due to strengthened surface wind regimes, the aeolian landforms appear widely, and the loess dposits accumulate continously. There exits a close linkage between the surface deposits on the Hexi Corridor and aeolian deposits in the downwind regions.
Key words: Asian dust source areas; surface deposits; positions; grain size;
1前言
全球对流层大气气溶胶(又名大气粉尘,释放通量约3500 Tg a-1)是指主要来源于沙漠及其周边戈壁滩地