华南鹿井矿田碎裂蚀变岩型铀矿床绿泥石特征及其地质意义——以小山铀矿床为例  

Characteristics and geological significance of chlorite from the cataclastic alteration granite-type uranium deposit in Lujing ore field,South China:Perspectives from Xiaoshan deposit

作　　者：许谱林 唐湘生 郭福生[1] 吕川 黎广荣[1] 党飞鹏 李志鹏 黄迪 徐勋胜 XU Pulin;TANG Xiangsheng;GUO Fusheng;LU Chuan;LI Guangrong;DANG Feipeng;LI Zhipeng;HUANG Di;XU Xunsheng(State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,Jiangri 330013,China;Research Institute No.270,CNNC,Nanchang,Jiangxi 330200,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]核工业二七〇研究所,江西南昌330200

出　　处：《地质学报》2023年第4期1211-1227,共17页Acta Geologica Sinica

基　　金：东华理工大学核资源与环境国家重点实验室开放基金(编号2020NRE07);中国铀业有限公司-东华理工大学核资源与环境国家重点实验室联合创新基金(编号NRE2021-08);中国核工业地质局项目(编号202231-11);国家自然科学基金项目(编号41972080);江西省技术创新引导类计划(编号20212AEI91008)联合资助的成果。

摘　　要：鹿井铀矿田位于桃山-诸广铀成矿带的南西部,是华南最主要花岗岩型铀矿田之一,碎裂蚀变岩型铀矿化在该矿田占主导地位,小山铀矿床是近年来新发现的碎裂蚀变岩型铀矿床之一。绿泥石化是该铀矿化重要的蚀变类型和找矿标志,然而针对绿泥石特征及其与铀成矿的关系研究较为薄弱。本文以钻孔ZK1-1揭露的热液蚀变带为研究对象,对绿泥石开展精细矿物学研究。结果表明:(1)小山铀矿床主要存在4种形态类型的绿泥石,分别为黑云母蚀变型、长石蚀变型、裂隙充填型和与铀矿物密切共生型;(2)绿泥石以富铁的铁镁绿泥石为主,部分为蠕绿泥石;(3)绿泥石的形成温度在213.5~249.8℃之间,平均值为233.4℃,属中低温条件;(4)绿泥石形成于低氧逸度、高硫逸度的还原环境,形成机制包括溶解—沉淀和溶解—迁移—沉淀,其中晶质铀矿、独居石以及磷钇矿矿物发生溶解,形成铀石—钍石矿物;(5)绿泥石蚀变改变了围岩性质、铀的赋存状态以及物理化学环境,促使铀的活化、迁移以及沉淀。The Lujing uranium ore field which is located in the southwest part of Taoshan-Zhuguang metallogenic belt is one of the most important granite type uranium ore field in South China.This ore field is dominated by the uranium mineralization related cataclastic alteration.The Xiaoshan uranium deposit is one of newly discovered cataclastic alteration granite-type deposits during recent years.Chloritization is the most important alteration type and prospecting indicator of the cataclastic alteration granite-type uranium deposits.However,the course of chloritization and its relationship with uranium mineralization has not been paid much attention.In this study,the mineralogy of chloritization from hydrothermal zone that was uncovered by drill core ZK-1 in Xiaoshan deposit has been carried out.The following conclusions have been reached in this study.(1)There are four types of chlorites,including chlorite of biotite alteration,chlorite of feldspar alteration,chlorite vein/veinlet filling in fissures,chlorite closely associated with uranium minerals.(2)The chlorites are mainly plotted in the brunsvigite area,partly plotted in the pycnochlorite.(3)The formation temperature of chlorites varies from 213.5℃to 249.8℃,at an average of 233.4℃,suggesting the chlorites were formed under medium to low temperature conditions.(4)The chlorites were formed under the reduced condition with low oxygen fugacity and high sulfur fugacity through two formation mechanisms of the dissolution-precipitation and the dissolution-migration-precipitation.The uraninite,monazite and xenotime are redissolved to form coffinite-thorite.(5)The chloritization has changed the properties of wall rocks,the occurring state of uranium in rocks and physicochemical environment and promoted the activation,migration and precipitation of uranium.

关 键 词：绿泥石 形成温度 物理化学环境 碎裂蚀变岩型铀矿 鹿井铀矿田 

分 类 号：P619.14[天文地球—矿床学]