康滇地轴巨粒晶质铀矿的发现及其地质意义

康滇地轴米易海塔地区富晶质铀矿石英脉产于晚元古代受混合岩化作用影响的五马箐组黑云斜长片岩中,受韧-脆性断裂构造裂隙带控制。晶质铀矿呈黑色,半金属光泽;晶形完好,以立方体与八面体聚形及菱形十二面体为主,少量呈立方体;粒径大多0.5cm左右,最大可达1cm以上。共生矿物组合为石英-晶质铀矿-榍石-辉钼矿组合。研究认为,晶质铀矿形成于温度压力较高及深度较大的地质环境,是高温偏酸性流体在温度缓慢下降的强还原条件下结晶而成的。康滇地轴具有形成高强度铀矿化的地质背景和成矿条件,在康滇地轴混合岩地区最有前景的铀矿类型应为受韧-脆性构造控制的中高温热液脉型矿化。

The discovery of coarse-grained uraninite in Kangdian Axis and its geological significance

The uraninite-bearing quartz veins from Haitain area of Miyi County along Kangdian Axis occur in the Wumaqing Formation consisting mainly of Late Proterozoic biotite-plagioclase schist, which was subjected to migmatization and controlled by ductile-brittle fault zone. Uraninite exhibits black and euhedral crystals composed of combination of cubes and octahedra as well as minor rhombic dodecahedra and cubes, with semi-metallic luster, from 0.5cm to 1cm in size. Mineral assemblage of uranium mineralization includes mainly quartz, uraninite, sphene and molybdenite. Researches show that uraninite formed in a high temperature and pressure geological environment in deep crust, derived from high temperature, acidic and reducing ore fluids. This discovery implies that Panxi area has especially favorable conditions for medium-high temperature hydrothermal vein-type uranium mineralization controlled by ductile-brittle faults in the migmatization region.