广西下雷氧化锰矿床矿石特征及成因分析  

Characteristics and Genesis of Supergene Manganese Ores in Xialei,Guangxi

作　　者：颜代蓉[1] 李建威[2] 胡明安[3] 郎银生[1] 

机构地区：[1]中国地质大学研究生院,武汉430074 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [3]中国地质大学资源学院,武汉430074

出　　处：《地质科技情报》2006年第3期61-67,共7页Geological Science and Technology Information

基　　金：国家自然科学基金资助项目(40202010)

摘　　要：广西下雷锰矿床由原生碳酸锰矿和次生氧化锰矿组成。其中氧化锰矿石的矿物主要有软锰矿、钡锰矿、隐钾锰矿、锂锰矿、钙锰矿、褐锰矿、黑镁铁锰矿等,与之伴生的其他表生矿物主要有赤铁矿、针铁矿、石英、高岭石和蒙脱石。矿石结构主要有交代、隐晶和细晶结构,矿石构造主要有葡萄状、块状、晶洞状、网脉状和条带状构造。与原生碳酸锰矿相比,次生氧化锰矿的矿石品位明显提高,平均在44%以上;Co、Ni、Cu、Zn等微量元素也有一定程度的富集。化学分析和单矿物成分分析结果表明,氧化锰矿石和锰氧化物中的w(Mn)/w(TFe)值均较高(一般大于10),说明风化强度大,铁、锰分离显著。与铁的氧化物相比,锰氧化物中Si和P等有害杂质元素的含量要低得多,因此,铁、锰分离是形成优质锰矿的重要条件。氧化锰矿的次生富集及其在空间上的分布受古气候、构造、含锰地层及地形地貌等多种因素的影响和控制。The Xialei Mn-oxides ore deposit, located in Guangxi, is the largest manganese producer in China. Manganese ores consist of sedimentary Mn-bearing carbonates and supergene Mn oxides. The supergene ores are mainly composed of hollandite, cryptomelane, lithiophorite, pyrolusite, braunite, todorokite, and jacobsite. Other secondary minerals intergrown with the Mn-oxides are hematite, goethite, quartz, kaolinite, and montmorillonite. Hollanite typically contain high barium contents, while cryptomelane is high in potassium concentrations resulting in high w（K）/w（Ba） ratio in the mineral. The highest manganese concentrations were seen in pyrolusite. However, this mineral precluded incorporation of other trace elements into its 1 × 1 tunnel structure. Lithiophorite is characterized by the high aluminum but relatively low manganese contents. Macroscopically, Mn-oxides commonly show botryoidal, massive, or banded structures, with cryptomerous or metasomatic texture. Contrasting with carbonate ores, manganese grade of the oxide ores are significantly enhanced due to supergene enrichments of the ore metal. A few kinds of trance elements such as Co, Ni, Cu and Zn are also enriched to some extent. Compared with Fe-oxides, Mn-oxides typically contain low P and Si contents, reflective of preferential incorporation of these impurity elements into Fe-oxides. The high w（Mn）/w（Fe） ratios suggest intense weathering and sufficient chemical separation between the Mn^- and Fe-oxides, which would have been important in the formation of high-quality Mn-ores. This study, when combined with existing data, suggests that formation and distribution of supergene Mn-oxides were jointly controlled by pre-enrichment of manganese in sedimentary rocks of wide distribution, wet and warm paeloclimate, relatively slow tectonic uplift and development of structure, and favorable geomorphologic units.

关 键 词：次生富集 氧化锰矿物 次生锰矿床 广西下雷 

分 类 号：P618.32[天文地球—矿床学]