印度次大陆中央构造带沉积—变质型锰矿的矿物学和地球化学  

Mineralogy and geochemistry of meta-sedimentary manganese deposits in the Central Indian Tectonic Zone

作　　者：杜小伟[1] 杨晓勇[1] 杨钟堂[2] L．G．Gwalani 

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026 [2]中国地质调查局西安地质矿产研究所,西安710054 [3]C/O The Unique Elect. Corporation,Nagpur 440001 ,India

出　　处：《地质科学》2009年第1期103-117,共15页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国科学院知识创新项目（编号：KZCX1-YW-15）资助.

摘　　要：对印度中央构造带Sausar带锰矿及其围岩的31个样品进行了显微镜仔细的观察和鉴定，并分析了其主量元素、微量元素和稀土元素的地球化学特征，发现该带的锰矿主要是软锰矿和硬锰矿，锰矿主要富集在锰榴石英岩内。含锰岩系样品具非常高的Mn/Fe比值，说明热液运输和成矿作用期间锰和铁的强烈分异；MnO/TiO2为67.98～1417.52，说明有大量陆源物质经风化、搬运加入并混合沉积而成。用太古界平均澳大利亚页岩（PAAS）标准化后，稀土元素含量中δEu，δCe都有明显的正异常，说明该带锰矿床是在较强氧化海洋环境和有大量陆源物质加入的条件下沉积，并经过热液的变质交代作用而成的沉积—变质型锰矿床。该沉积—变质型锰矿的发现和研究对我国南方扬子克拉通中元古代浅变质岩系的锰矿寻找具有一定的借鉴意义。31 samples of manganese minerals and their country rocks from Sausar belt in the Indian Central Tectonic Zone were observed and identified with microscope,stereoscan and X-ray powder-crystal,and their major and trace elements＇, and REE＇s geochemical characters were analyzed by XRD and ICP-MS. The manganese minerals in the belt were mainly pyrolusite and psilomelane, enriched in gondite. In the manganiferous rock series, Mn/Fe was extremely high, resulted from strong fractionation between manganese and iron during hydrothermal transportation and metallization. MnO/TiO2 ratios ranged in 67.98 - 1417.52,indicating that quantities of terrigenous materials added to the deposition by weathering,transportation and mixing. Normalized to PAAS,both δEu and δCe were obviously positive, suggesting that the manganese deposit was formed by addition of quantities of terrigenous materials in some oxidative marine environment,then experienced hydrotbermal metamorphism and metasomatism. The study should be significant for Mn-prospecting in Middle Proterozic meta-sedimentary series in the Yangtze craton.

关 键 词：沉积—变质型锰矿 锰榴石英岩 REE地球化学 矿物学 印度次大陆中央构造带 

分 类 号：P618[天文地球—矿床学]