黔西南富钪红土风化剖面的地球化学特征  

Geochemical characteristics of the Sc-rich laterite of a weathering profile in the southwestern Guizhou

作　　者：覃山县 唐勇[1] 金中国 QIN Shan-xian;TANG Yong;JIN Zhong-guo(CAS Key Laboratory of High-Temperature and High-Pressure Study of the Earth's Interior,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;University of the Chinese Academy of Sciences,Beijing 100049,China;Guizhou Nonferrous Metal and Nuclear Industry Geological Exploration Bureau,Guiyang 550005,China)

机构地区：[1]中国科学院地球化学研究所地球内部物质高温高压重点实验室,贵州贵阳550081 [2]中国科学院大学,北京100049 [3]贵州省有色金属和核工业地质勘查局,贵州贵阳550005

出　　处：《矿物学报》2022年第6期825-839,共15页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:41773053)。

摘　　要：本文对黔西南晴隆沙子矿区富钪红土风化剖面的地球化学特征进行了研究。结果表明:1)常量元素数据分析显示,沙子剖面均经历了强烈的脱硅去碱和富铁铝钛的作用,镁和钙变化特征指示沙子剖面含较少的蒙脱石,形成于风化的晚期阶段,CIA指数亦表明,沙子剖面经历了强烈的风化作用;2)沙子剖面的稀土元素具有明显的正δCe异常,表明沙子剖面形成于强氧化环境,母岩中钪的含量以及风化程度控制了风化壳中钪的含量,沙子剖面中的Sc在风化壳中相对母岩富集,以红土层富集最明显,沙子剖面富集程度为母岩的1.26~1.96倍;3)不同次生矿物对钪和稀土吸附能力的差别,导致了钪和稀土元素在风化剖面中的富集层位不同。本文通过对沙子剖面钪矿床的形成过程研究,将为建立基性-超基性岩中红土型钪矿的成矿理论提供依据。The geochemical characteristics of the scandium-rich laterite of a weathering profile in the Shazi area,Qinglong County of the southwestern Guizhou have been studied in this paper.The research results are given below.(1)The analyses of major elements show that laterites of the Shazi profile were formed through strong desilication,dealkalization and enrichment of iron,aluminum and titanium in the weathering process of original rocks.The variation characteristics of Mg and Ca contents of laterites of the Shazi profile indicate that the laterites contain minor montmorillonite which was formed in the late stage of weathering.Chemical Indexes of Alteration also indicate that laterites of the Shazi profile were resulted from the strong weathering of original rocks;(2)The distribution patterns of rare earth elements of laterites in the Shazi profile have obvious positive δCe anomalies,indicating that the laterite of the Shazi profile was formed in a strong oxidized environment.The scandium contents in parent rocks and the degrees of weathering controlled scandium contents of the weathering crust.Sc is enriched in weathering crust of the Shazi profile relative to the parent rocks,with the most obvious enrichment of Sc in the laterite layer.The enriched Sc contents of weathered rocks in the Shazi profile are 1.26-1.96 times of those of their parent rocks;(3)The differences of adsorption capacities of scandium and rare earth elements by different secondary minerals resulted in different enrichment layers of scandium and rare earth elements in the weathering profile.In this paper,the study on the formation process of scandium ore body in the Shazi area will provide the basis for establishing the metallogenic theory of the laterite-type scandium deposit in strongly weathered basic-ultrabasic rocks.

关 键 词：红土型风化剖面 脱硅去碱 氧化环境 吸附 成矿理论 

分 类 号：P594.2[天文地球—地球化学] P611.2[天文地球—地质学] P618.73