黔中猫场杨家洞矿段铝土矿中富钴黄铁矿的发现与意义  

Discovery of cobalt-rich pyrite in the Yangjiadong ore block of the Maochang bauxite deposit, Guizhou Province and its significance

作　　者：王宇非 王智琳 鲁安怀 吴林 许德如 吴涛 龙永珍 黄智龙[2] 范宏鹏[2] 彭尔柯 WANG Yu-fei;WANG Zhi-lin;LU An-huai;WU Lin;XU De-ru;WU Tao;LONG Yong-zhen;HUANG Zhi-long;FAN Hong-peng;PENG Er-ke(Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring(Central South University),Ministry of Education,School of Geosciences and Info-Physics,Central South University,Changsha 410083,China;State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China)

机构地区：[1]中南大学地球科学与信息物理学院有色金属成矿预测与地质环境监测教育部重点实验室,湖南长沙410083 [2]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550081 [3]中国科学院大学,北京100049 [4]东华理工大学省部共建核资源与环境国家重点实验室,江西南昌330013

出　　处：《矿物学报》2021年第4期460-474,共15页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:41672077;41930428);中南大学有色金属成矿预测与地质环境监测教育部重点实验室开放基金项目(编号:No.2020YSJS03)。

摘　　要：铝土矿中伴生有Li、Ga、V、Cr、REE、Sc、Co、Ni、Nb、Zr、W等关键金属。黔中猫场铝土矿是我国最大的隐伏铝土矿矿床,已发现伴生有镓、钪和锂等关键矿产资源,然而对硫铁矿中可能伴生的关键金属尚未引起足够的重视,本文系统开展了猫场杨家洞矿段中不同类型含矿岩系及矿石中黄铁矿的精细矿物学工作。结果表明,杨家洞矿段黄铁矿具有复杂的结构和成因,可分为沉积黄铁矿(PyI)和热液黄铁矿(PyII)等2大成因。前者以草莓状或细粒结构为特征;后者从早到晚进一步划分为3个世代:PyⅡ-1、PyⅡ-2和PyⅡ-3,其中PyⅡ-2呈不规则状交代或增生于PyⅡ-1颗粒的边部,PyⅡ-3呈脉状或网脉状切穿早期的黄铁矿。电子探针分析结果表明,PyⅡ-2具有明显高于其他世代黄铁矿的Co和As含量,分别高达9.31%和2.98%,揭示猫场硫铁矿中钴元素的富集与后期热液活动密切相关。Co与Fe明显的负相关性反映Co主要以类质同象的方式赋存于黄铁矿晶格内,PyⅡ-2和PyⅡ-1截然的接触界线和不同的化学成分暗示富钴黄铁矿PyⅡ-2主要由耦合的溶解-再沉淀作用形成。猫场铝土矿中富钴黄铁矿的发现为猫场矿区硫铁矿的综合回收利用乃至黔中地区铝土矿中伴生关键金属类型找矿提供了新的方向。The karstic bauxites commonly host numerous associated critical metals such as lithium, gallium,vanadium, chromium, REE, scandium, cobalt, nickel, niobium, zirconium, and tungsten. The Maochang bauxite deposit in the central Guizhou is the largest concealed bauxite deposit in China, with a certain amount of associated critical metals of gallium, scandium, and lithium. However, associated critical metals in the pyrite have not been paid enough attention yet. In this paper, we have systematically carried out the study on the mineralogy of pyrites from various types of bauxite-bearing rocks in the Yangjiadong ore block of the Maochang deposit. The results show that those pyrites have complex textures and genesis. Two kinds of pyrites including the sedimentary one(PyⅠ) and hydrothermal one(PyⅡ) have been identified. The PyⅠ is characterized with framboid or fine-grained textures, whereas the PyⅡ occurred as veins/veinlets or cements of breccias and can be subdivided into three generations of PyⅡ-1, PyⅡ-2 and PyⅡ-3. The rim of PyⅡ-1 grain was commonly replaced or overgrown by irregular PyⅡ-2, and these two generations of pyrites(PyⅡ-1 and PyⅡ-2) were cut by PyⅡ-3 veins or stockwork veins. The EPMA analyses show that the PyⅡ-2 has significantly higher Co(up to 9.31%) and As(up to 2.98%) contents than other generations of pyrites, and thus it is confirmed that the late hydrothermal activity could greatly contribute to the enrichment of cobalt in the PyⅡ-2. The obvious negative correlation between Co and Fe contents reflects that Co was mainly incorporated in lattice of pyrite in form of isomorphism The sharp contacts and distinct chemical compositions between PyⅡ-1 and PyⅡ-2 pyrites suggest that the Co-rich pyrite(PyⅡ-2) was mainly formed by the coupled dissolution and reprecipitation of the precursor PyⅡ-1. The discovery of Co-rich pyrite in the Maochang bauxite deposit has not only provided a new direction for the comprehensive recycling and utilization of Co in the pyrite of the Ma

关 键 词：猫场铝土矿 富钴黄铁矿 伴生关键金属 黔中地区 

分 类 号：P571[天文地球—矿物学] P611[天文地球—地质学]