江西乐安居隆庵铀矿床绿泥石特征及地质意义

Mineral characteristics and geological significance of chlorite from the Julong'an uranium deposit in Le'an,Jiangxi Province

位于相山铀矿田西部的居隆庵铀矿床绿泥石化十分强烈,本文在对钻孔岩心样详细的野外和室内岩相学观测基础上,利用电子探针技术研究了绿泥石的产出状态及共生组合关系,并测定了其化学成分,探讨了该矿床绿泥石地球化学特征及其与铀矿成矿的关系。研究表明:①该矿床存在黑云母蚀变形成的绿泥石、长石蚀变形成的绿泥石、脉状绿泥石和与铀矿密切共生的绿泥石共4种类型绿泥石;②该矿床以蠕绿泥石和铁镁绿泥石为主,个别为鲕绿泥石,其形成温度介于190.5~269.9℃之间,平均为224.5℃,属于中低温条件;③该矿床绿泥石形成于还原环境,形成机制分为溶解-沉淀机制和溶解-迁移-沉淀机制两种;④绿泥石化过程改变了围岩的物理化学性质,改变了铀在岩石中的赋存状态并促使铀的预富集。

Located in the west of Xiangshan area, the Julong＇an uranium deposit has undergone strong chloritization. Based on detailed field investigation and indoor petrographic observation, the authors studied the production state, association relation and chemical composition by applying the electron microprobe technology to the drill hole samples and investigated geochemical features of the chlorite deposit and its relationship with uranium mineralization. Some conclusions have been reached： ① There are four types of chlorites： chlorite from biotite alteration, chlorite from feldspar alteration, colloidal chlorite and uranium-associated chlorite; ② The major chlorites in the deposit are chlorophaeite and brunsvigite, with a small amount of chamosite. The temperature of chlorite varies from 190.5 to 269.9℃, with an average of 224.5℃, suggesting a medium and low temperature condition; ③ The chlorite deposit was formed in a relative reduction environment, with the two formation mechanisms being dissolution-precipitation and dissolution-migration-precipitation; ④ The process of chloritization changed the physical and chemical properties of surrounding rocks and accelerated uranium activation and preenrichment