Acta Geographica Sinica ›› 2002, Vol. 57 ›› Issue (3): 293-300.doi: 10.11821/xb200203005

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A Development Model of Red Weathering Crust on Limestones: an Example from Hunan, Guangxi, Guizhou, Yunnan and Tibet

LI Dewen1, CUI Zhijiu2, LIU Gengnian2   

  1. 1. Department of Geography, Nanjing University, Nanjing 210093, China;
    2. Department of Geography, Peking University, Beijing 100871, China
  • Received:2001-06-04 Revised:2001-09-26 Online:2002-05-25 Published:2010-09-06
  • Supported by:

    National Key Project for Basic Research, No.G1998040800); CAS Project for Tibetan Research, No.KZ951-A1-204; No.KZ95T-06; China Postdoctoral Science Foundation

Abstract:

Based on research results of red weathering curst on limestones (WCL) in Hunan, Guangxi, Guizhou, Yunnan and Tibet, the authors analysed the relationship of red WCL and evolution of landforms using principles of geomorphology, clay mineralogy and geochemistry, and put forward a two-stage development model. Firstly, insoluble residual of carbonates have been cumulated in the later stage of geographical cycle and WCL was formed on planation surface (PS). This is called stage of lowering of landform and accumulation of residual or stage of planation and crustal formation. The gentle relief and backwater, derived from PS (in humid tropical), is available for the formation and preservation of clays (argilication), but restricts WCL to effective allitication. This accords with the characters of WCL in the study areas (including chemical composition and mineralogical assemblage of clays and granularity of 23 profiles). The second stage of the above model is incision of landform and allitication of WCL or incision-erubescence. The initial WCL located on PS is mainly gray due to reductive circumstance. WCL will have changed from gray (reductive) to red (oxidative) if only tectonic uplift and incision of rivers lower groundwater table, and geomorphologic and hydrogeological (hydrological) conditions have promoted to allitication. This is confirmed using material of field investigations. The WCL on the initial PS, such as Hunan and Guangxi, is mainly gray-color and those on the uplifted plateau, such as Yunnan-Guizhou and Tibetan plateaus, is red. In addition, red WCL is spatially located on PS.

Key words: red weathering crust on limestones, development model of two-stage, planation surface, tectonic uplift, Tibetan Plateau, Yunnan-Guizhou Plateau