相山横涧-岗上英铀矿床围岩蚀变及地球化学特征

摘要

以相山横涧-岗上英铀矿床为研究对象,笔者通过显微镜下薄片鉴定、电子探针测试及岩石地球化学分析等方法,对该矿床的围岩蚀变及地球化学特征进行了系统研究.结果表明,矿床的蚀变种类繁多,主要有水云母化、钠长石化、绿泥石化、碳酸盐化、萤石化、黄铁矿化和硅化等.矿床具有明显的蚀变分带特征,可分为5个蚀变带.赋矿围岩(花岗斑岩)的岩石地球化学特征显示其具有高硅、富碱、低钙镁的准铝质-过铝质特性.蚀变岩石主量、微量及稀土元素含量均有规律变化；主量元素(Ca、Mn、K)、不相容元素(Sr、Th、P、Y、Yb)和重稀土元素明显富集,Mo、W、Pb、Zn是寻找铀矿化的指示性元素.蚀变岩微量元素分布模式和稀土元素配分模式与正常围岩的模式一致,表明蚀变作用对它们的影响较小,成矿物质具有深源特征.%With the method of thin section identification, electron probe and the petrochemical analysis, wall rock alteration and geochemical characteristic was studied for Hengjiang - Gangshangying uranium deposit in Xiangshan. The results show that the deposit has a variety of alteration, which include hydrom-icazation, albitization, chloritization, carbonation, fluoritization, pyritization, and silicification. The alteration can be easily divided in five zones petrochemically, the hosting rock (granite porphyry) are of quasi aluminium to peraluminous which is high in Si and alkali and low in calcium - magnesium. Major elements, trace elements and rare elements in the alteration rock show regular variations and the values of major elements Ca, Mn, K and incompatible elements Sr, Th, P, Y, Yb and HREE have been increased in mineralization process. Mo, W, Pb, Zn can be used as indicator elements for uranium mineralization. The alterated rock has the same geochemical characteristics as the ore - hosting rock body which can be proven by the consistent distribution patterns of trace elements and rare elements. The mineralization material bears the characteristics of deeply - derived source.