地理学报

地理学报 ›› 2001, Vol. 56 ›› Issue (5): 515-522.doi: 10.11821/xb200105002

• 论文 • 上一篇    下一篇

长江三峡坝区花岗岩风化壳化学元素迁移特征

张丽萍1, 朱大奎2, 杨达源2   

  1. 1. 浙江大学土水资源与环境研究所,杭州310029;
    2. 南京大学大地海洋系,南京210093
  • 收稿日期:2001-03-13 修回日期:2001-05-17 出版日期:2001-09-15 发布日期:2001-09-15
  • 基金资助:
    中国长江三峡工程开发总公司“长江三峡坝区河谷发育演变与深槽成因研究”项目;2000年浙江大学人才引进基金资助

Chemical Element Transferring Features of Weathering Granite Regolith in Three Gorges Dam Region

ZHANG Li ping1, ZHU Da kui2, YANG Da yuan 2   

  1. 1. Institute of Soil and Water Resources and Environment, Zhejiang University, Hangzhou 310029, China;
    2. Department of Geo and Ocean Science, Nanjing University, Nanjing 210093, China
  • Received:2001-03-13 Revised:2001-05-17 Online:2001-09-15 Published:2001-09-15
  • Supported by:
    Supported by The Project of“Study on Deep Trough Formation and River Valley Development in The Three Gorges Dam Region of Yangtze River”From Exploitation Corporation of The Three Gorges Project of Yangtze River in China Foundation,and“Attracting Person of Ability”Zhejiang University Foundation

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摘要： 在长江三峡坝区河谷不同地貌部位系统采样的基础上,通过 X射线荧光光谱的化学全量分析及各元素迁移率特征值和强度值的详细计算,揭示出不同地貌部位各化学元素的迁移规律 :1长期淹没于水下的河床风化壳,易溶的 Ca O、Mg O发生相对富集的现象,Al2 O3却呈减少的趋势 ;Fe2 O3的富集率最大 ;2季节性被水浸没的河漫滩风化壳,还出现了 K2 O、Mg O含量相对富集的现象 ;3谷坡风化壳是典型的北亚热带地带性风化壳,处于化学风化早期到中期的过渡阶段。 4在各种地貌的风化壳中 6.5深度是一个特殊的层位,K2 O、 Na2 O对抗现象最为明显,即 Na2 O相对富集,K2 O相对减少。

关键词: 三峡坝区, 花岗岩, 风化壳, 化学元素, 迁移

Abstract: The exposure of river valley including riverbed as a result of clearing up sediment and regolith on the foundation of dam in the Three Gorges of the Yangtze River in 1999, river valley including riverbed was exposed which offered a good opportunity to research river valley landforms The chemical element transferring features in different valley landform positions are mainly researched in this paper 1 Sample collection:In lower 100 m of dam foundation, 50 samples were collected along NE42 ? trending cross section of river valley, at 3 different elevations (riverbed, flood plain, valley slope) and 6 typical columnar sections 2 Analysis:Based on the X rays fluorescent slice, weathering ratio, chemical element transferring ratio, the coefficient of average dripping and washing, the intensity of weathering were further calculated in detail 3 Conclusions:(1) In various landform positions of the river valley, the process of desilication is not distinct (2) In riverbed weathering granite regolith, easy soluble CaO and MgO are relatively concentrated on the contrary, Al 2O 3 shows a tendency to decrease The concentrated rate of Fe 2O 3 is the greatest in various landform positions of the river valley (3) In flood plain weathering granite regolith, K 2O and MgO contents are relatively concentrated (4) River valley slope weathering granite regolith is a typical northern subtropical weathering regolith, and its chemical weathering degree is in the transitional period from early phase to middle phase (5) In the upper middle layer of vertical columnar section in riverbed and valley slope weathering granite regolith, there is a concentrated layer of easy soluble elements and a leached layer of concentrated elements (6) Element transferring absolute intensity of riverbed weathering granite regolith is the greatest of three landform positions The order of element transferring relative intensity is flood plain weathering granite regolith > riverbed weathering granite regolith > valley slope weathering granite regolith The above mentioned conclusions indicated that, under certain climate conditions, chemical elements are transferred along with landform and water circulation in weathering granite regolith.

Key words: Three Gorges Dam region, granite, weathering regolith, chemical element, transferring

中图分类号: 

  • P512.1