酸不溶物对碳酸盐岩风化壳发育程度的影响  

Impact of Acid-Insoluble Residua of Carbonate Rocks on Developing Intensities of Their Weathering Crusts

作　　者：冯志刚[1,2] 王世杰[1] 刘秀明[1] 罗维均[1] 

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002 [2]南华大学核资源与安全工程学院,湖南衡阳421001

出　　处：《地质学报》2009年第6期885-893,共9页Acta Geologica Sinica

基　　金：国家重点基础研究发展计划项目(编号2006CB403200);湖南省自然科学联合基金项目(编号06JJ50074);中国科学院地球化学研究所环境地球化学国家重点实验室开放基金项目(编号SKLEG5076)资助成果

摘　　要：通过对贵州岩溶区(包括湘西)不同地层系统碳酸盐岩发育的红色风化壳、以及结合本区和处于同一气候带的邻区不同岩类红色风化壳的对比研究,结果表明①在风化条件不是特别强烈的区域,碳酸盐岩红色风化壳的发育程度明显受基岩酸不溶物成分的控制,酸不溶物的风化成熟度越高,红色风化壳的发育程度一般也越强。由于不同地层系统碳酸盐岩的酸不溶物组成不同,在此基础上发育的红色风化壳的风化强度自然存在着差异;②风化壳相对于母岩的进一步风化潜力或空间,随着基岩酸不溶物风化成熟度的增大而降低,从而更容易达到风化平衡;③在碳酸盐岩风化壳突变的岩-土界面,伴随碳酸盐的充分淋失,酸不溶物的地球化学指标发生了突变。因此,碳酸盐的溶解不但未阻滞和延缓了硅酸盐组分的分解,而且促进其快速风化;④在达到高岭石化甚至弱红土化阶段的酸不溶物基础上,发育的风化壳比结晶岩类风化壳具有更高的风化起点,也就表现出更高的风化强度。因此,笼统地把碳酸盐岩风化壳看作是弱于玄武岩及花岗岩等结晶岩类风化壳发育程度的弱风化类型是不妥的。Through studying weathering characteristics of red weathering crusts developed on carbonate rocks from different stratum systems in the Guizhou karst region （including western Hunan Province）, and comparing with those developed on other types of bed rocks in native and ambient areas in the same climatic zone, we draw conclusions as follows： （1） In the regions where weathering is not much intense, weathering intensities of red weathering crusts of carbonate rocks are affected markedly by the components of their acid-insoluble residua, and the higher weathering maturity of acid-insoluble residue, in general,the more intense weathering degree of red weathering crust. Owing to the fact that different stratum systems have different compositions of acid-insoluble residua, weathering intensities of red weathering crusts based on them are certainly distinct. （2） Further weathering potential of weathering crust falls along with increasing of weathering maturity of acid-insoluble residue, and consequently weathering equilibrium can be reached more easily. （3） At the sharply transitional interface between rock and soil,geochemical index of acid-insoluble residua change distinctly along with leaching loss of carbonate.Therefore, the dissolution of carbonate accelerates the weathering of silicate compositions instead of retarding its decomposition. （4） Owning to occurrence of acid-insoluble residua of carbonate rocks during kaolinization and even weak laterization, weathering crusts of carbonate rock are more vulnerable to weathering than that of crystalline rocks, and show a high weathering intensity. Therefore, it is not appropriate to classify the weathering crust of carbonate into the weak weathering type, which is even much weaker than that of crystallized rock weathering types such as basalt and granite.

关 键 词：酸不溶物 碳酸盐岩风化壳 风化强度 不同母岩类型 贵州岩溶区 

分 类 号：P618.13[天文地球—矿床学]