湘桂黔滇藏红色岩溶风化壳发育模式

基于对湘，桂、黔，滇，藏等地岩溶区红色风化壳的野外和室内研究，从表生地貌学，粘土矿物学和地球化学角度分析红色石灰土性质与地貌演化的关系，提出红色岩溶风化壳发育的二阶段模式；1）地貌夷平-风化物质积累阶段，在地貌演化过程中溶蚀残余物质不断积累，最后在夷平面上形成厚层连续的泥质风化壳，夷平面的地貌水文条件有利于粘粒的形成和保存，但限制了富铝化作用的有效进行，造就了岩溶风化壳粘粒含量高，富铝化程度低的特点，这与研究区23个红色岩溶风化壳剖面化学，粒度特征和粘土矿物组合特点一致。2）地貌切割-风化壳淋溶阶段，原始夷平面上的风化壳大多呈灰色，只有在构造隆升和地表微切割导致地下水位降低，淋溶条件开始改善的情况下，风化壳才有可能枞根本上转为红色。

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

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 andevolution of landforms using principles of geomorphology, clay mineralogy and geochemistry,and pot forward a two-stage development model. Firstiy, insoluble residual of carbonates havebeen cumulated in the later stage of geographical cycle and WCL was formed on planationsurface (PS). This is called stage of lowering of landform and accumulation of residual orstage of planation and crustal formation. The gentle relief and backwater, derived from PS (inhumid tropical), is available for the formation and Preservation of clays (argilication), butrestricts WCL to effective allitication. This accords with the characters of WCL in the studyareas (including chemical composition and nineralogical assemblage of clays and granularityof 23 profiles). The second stage of the above model is incision of landform and alliticationof WCL or incision-erubescence. The initial WCL located on PS is mainly gray due toreductive circumstance. WCL will have changed from gray (reductive) to red (oxidative) ifonly tectonic uplift and incision of rivers lower groundwater table, and geomorphologic andhydrgeological (hydrological) conditions have promoted to allitication. This is confirmedusing material of field investigations. The WCL on the initial PS, such as Hunan andGuangxi, is mainly gray-color and those on the uplifted plateau, such as Yunnan-Guizhou andTibetan plateaus, is red. In addition, red WCL is spatially located on PS.