地理学报 ›› 2002, Vol. 57 ›› Issue (3): 267-274.doi: 10.11821/xb200203002

• 论文 • 上一篇    下一篇

青藏高原古岩溶的性质、发育时代和环境特征

高全洲1, 崔之久2, 陶贞1, 刘耕年2, 洪云3   

  1. 1. 中山大学地理学系, 广州 510275;
    2. 北京大学城市与环境学系, 北京 100871;
    3. 国家环保局, 北京 100035
  • 收稿日期:2001-06-04 修回日期:2001-09-26 出版日期:2002-05-25 发布日期:2010-09-06
  • 作者简介:高全洲 (1965- ), 副教授, 安徽人。从事地貌学与环境地球化学研究和教学工作, 发表论文40多篇。E-mail: eesgqz@zsu.edu.cn
  • 基金资助:

    国家自然科学基金资助项目 (49901002; 49371011)

The Nature, Formation Age and Genetic Environment of the Palaeokarst on the Qinghai-Xizang Plateau

GAO Quanzhou1, CUI Zhijiu2, TAO Zhen1, LIU Gengnian2, HONG Yun3   

  1. 1. Department of Geography, Zhongshan University, Guangzhou 510275, China;
    2. Department of Geography, Peking University, Beijing 100871, China;
    3. State Environmental Protection Agency, Beijing 100035, China
  • Received:2001-06-04 Revised:2001-09-26 Online:2002-05-25 Published:2010-09-06
  • Supported by:

    The National Natural Science Foundation of China, No. 49901002; No. 49371011

摘要:

青藏高原目前多处所见岩溶地貌主要属第三纪古岩溶之地下部分经后期剥蚀而出露于地表的。风化壳红土和洞穴次生化学沉积等古岩溶相关沉积也多以残留形态出露在已经发生解体的高原主夷平面的南和东南缘。风化壳红土中所含粘粒部分的主要化学成分为SiO2、Al2O3和Fe2O3;粘土矿物多属“伊利石-高岭石”型组合,少数样品属“高岭石-伊利石”型组合。据硅酸系数和粘土矿物组合判断,古岩溶风化壳红土的发育阶段处在化学风化的初期,但由于目前所见红土仅反映当时风化壳剖面根部的化学风化状况,故其较弱的风化指数仍能间接指示古岩溶发育时期湿热的地表环境。扫描电镜观测结果亦表明,风化壳红土中石英砂的表面结构特征以化学溶蚀形成的为主,机械侵蚀形成的为辅,反映了高原风化壳红土的长期残留特征,对应风化壳发育时期的湿热环境。

关键词: 古岩溶, 风化壳红土, 化学风化, 第三纪, 夷平面, 青藏高原

Abstract:

The karst landforms scattering on the Qinghai-Xizang (Tibet) Plateau can be genetically classified as the Tertiary underground karst, which gradually emerged to the ground surface following later period's denudation with the uplift of the plateau during the Quaternary Period. The relative deposits of the Tertiary palaeokarst processes, such as the residuum and speleothem, were discovered recently on the plantation surface of the plateau, where both eastern and southeastern fringe has geologically been disintegrated. The results of fission track dating using the speleothem calcite revealed that the formation age of the palaeokarst and hence the plantation surface is between 19.0 and 7.0 Ma B.P. The residuum has a fine size distribution. The principal chemical components of the clay portion of the residuum consist mainly of SiO2, Al2O3 and Fe2O3. The clay minerals composition of the clay portion belongs to illite-kaolinite-type for most of the residuum samples, and kaolinite-illite-type for a few samples. It can be judged from the silicic acid index and the clay minerals composition that the formation of the residuum of the Qinghai-Xizang Plateau was in its initial phase. However, such a weak chemical weathering index only reflected the weathering degree in the bottom or lower parts of the weathering crust. The relative intensive chemical weathering processes of the surface layers of the weathering crust could be logically speculated. Also, surface textures of quartz grains in the residuum produced by chemical erosion revealed a long-term humid-tropical environment when the residuum and the palaeokarst formed.

Key words: palaeokarst, residuum, chemical weathering, Tertiary Period, planation surface, the Qinghai-Xizang