福建李坊重晶石矿床矿石结构特征及矿石矿物学研究

Petrofabric and Mineralogy Constraints on the Genesis of the Lifang Barite Deposit,Fujian Province

福建李坊重晶石矿床是闽浙地区发现的唯一的一个大型独立重晶石矿床,为厘清其成因,本文对矿床中的矿石和围岩进行了详细的组构和矿相学研究。结果显示,重晶石矿石具有角砾状构造、碳膜构造、蜂窝构造、管孔构造等典型热水沉积构造;围岩也具有碳膜构造、块状构造和条带状构造等热水沉积构造。且矿石与围岩具有同沉积的特征。另外,对采自435中段的层状矿体中的10件重晶石矿石样品还进行了电子探针成分分析,结果表明矿石的主要矿物为重晶石,其主要成分Ba O含量为62. 905%~65. 737%,SO3含量为34. 263%~37. 235%,Al2O3为0. 058%~0. 216%,Sr O为0. 190%~0. 363%,反映重晶石的形成可能与热卤水的活动有关。矿石中的次要矿物为钡冰长石、钡长石和黄铁矿,偶见钡云母和方解石。在SiO2/(Na2O+K2O)-MnO/TiO图解上,样品点全部落入热水成因区。综上研究认为李坊重晶石矿床为热水沉积成因。

The Lifang barite deposit in Fujian Province is the largest independent barite deposit that have been found in Fujian and Zhejiang areas. In order to constrain the origin of deposit,petrofabric and mineralogy studies of ores and wall rocks have been carried out. Barite ores are characterized by brecciated,carbon membrane and honeycomb structures,indicative of hydrothermal sedimentation. In contrast,structures of wall rocks include carbon membrane,massive and banded structures,showing similar origin as ores. Ores is mainly composed of barite,with minor celsian,hyalophane and pyrite and trace barium-mica and calcite. Barite contains BaO is 62. 905% to 65. 737%,SO3 is 34. 263% to 37. 235%,Al2 O3 is 0. 058% to 0. 216% and SrO is 0. 190% to 0. 363%. On the plot of SiO2/(Na2 O+K2 O)-MnO/TiO,all samples plot in the region of hydrothermal sedimentation. Therefore,structures and ore mineral geochemical characteristics suggest that Lifang barite deposit was formed by hydrothermal sedimentation.