电子探针和LA-ICP-MS技术研究内蒙古浩尧尔忽洞金矿床毒砂矿物学特征  

Application of EPMA and LA-ICP-MS to Study Mineralogy of Arsenopyrite from the Haoyaoerhudong Gold Deposit,Inner Mongolia,China

作　　者：员媛娇 范成龙[2] 吕喜平 史哲锋 窦智慧 王义天[1] 王梦琦 叶会寿[1] YUN Yuanjiao;FAN Chenglong;LYU Xiping;SHI Zhefeng;DOU Zhihui;WANG Yitian;WANG Mengqi;YE Huishou(Key Laboratory of Metallogeny and Mineral Assessment,Ministry of Natural Resources,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Bejjing 100037,China;School of Earth Science and ResourcesChina University of Geosciences(Bejjing),Beijing 100083,China;Inner Mongolia Pacifie Mining Co.,Ltd.,Wulatezhongqi 015308,China)

机构地区：[1]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]内蒙古太平矿业有限公司,内蒙古乌拉特中旗015308

出　　处：《岩矿测试》2022年第2期211-225,共15页Rock and Mineral Analysis

基　　金：国家自然科学基金项目(41972311,41672330);中国黄金集团有限公司2019年地质科研项目“内蒙古乌拉特中旗浩尧尔忽洞金矿成矿规律与找矿预测研究”。

摘　　要：毒砂的主微量元素组成可以用于判断元素的赋存状态,探讨元素在不同阶段的活化迁移行为。内蒙古浩尧尔忽洞金矿床是产自白云鄂博群黑色岩系中的一个超大型金矿,发育重要载金矿物毒砂和斜方砷铁矿。前人利用传统粉末溶样法对矿石进行同位素分析,探讨了成矿物质来源,但金的迁移富集机制尚未获得解决。为探讨该矿床金迁移富集过程,本文在矿相学的基础上,对不同类型的毒砂进行电子探针(EPMA)和电感耦合等离子体质谱(ICP-MS)测试。所测得的电子探针数据经ZAF程序校正,LA-ICP-MS数据采用“无内标-基体归一法”进行定量计算,可以有效地分析微区成分。结果显示:毒砂(Apy)内部发育斜方砷铁矿(Lo),可分为递进剪切变形阶段的Apy-Ⅰ1、Apy-Ⅰ2、Lo-Ⅰ和后剪切变形阶段的Apy-Ⅱ1、Apy-Ⅱ2、Lo-Ⅱ。各世代毒砂主元素组成稳定,含有少量Co、Ni和微量Sb、Te、Bi、Pb、Au、Ag。其中,Co在Apy-Ⅱ1和Apy-Ⅱ2中偏高,微量元素Au、Bi、Pb、Te在Apy-Ⅰ1中明显富集。斜方砷铁矿富As(64.06%~67.87%),含Co(0.33%~4.98%)、Ni(1.23%~6.37%),微量元素Au、Te、Bi、Pb、Ag在Lo-Ⅱ中更富集。研究表明,Lo-Ⅱ是最主要的载金矿物,温度和硫逸度的变化导致了斜方砷铁矿和自然金的沉淀,自然金是由早期毒砂和斜方砷铁矿的“不可见金”经活化再迁移沉淀形成。BACKGROUND: The composition of major and trace elements in arsenopyrite can be used to identify the occurrence of elements and explore the remobilization and migration behaviour of elements in different stages. The Haoyaoerhudong gold deposit in Inner Mongolia is a super large gold deposit hosted in the black shales of the Bayan Obo Group. Gold-bearing minerals such as arsenopyrite and loellingite are present. Previous researchers have used the traditional powder dissolution method to analyze the isotope of the ore and discussed the source of ore-forming materials, but the migration and enrichment mechanism of gold has not been unraveled.OBJECTIVES: To understand the gold migration and enrichment process of this deposit.METHODS: Based on mineralogy, different types of arsenopyrite were analyzed by electron probe microanalyzer(EPMA) and inductively coupled plasma-mass spectrometry(ICP-MS). The data measured by EPMA was corrected by ZAF program, and the data measured by LA-ICP-MS was quantitatively calculated by “no internal standard-matrix normalized calibration”.RESULTS: The results showed that loellingite was developed in arsenopyrite. They can be divided into Apy-Ⅰ1, Apy-Ⅰ2, Lo-Ⅰ in progressive shear deformation stage and Apy-Ⅱ1, Apy-Ⅱ2 and Lo-Ⅱ in post shear deformation stage. The major element composition of arsenopyrite in different generations was stable, with a small amount of Co and Ni and a trace amount of Sb, Te, Bi, Pb, Au and Ag. Cobalt was higher in Apy-Ⅱ1 and Apy-Ⅱ2, whereas Au, Bi, Pb and Te were obviously enriched in Apy-Ⅰ1. Loellingite was rich in As(64.06%-67.87%), Co(0.33%-4.98%), Ni(1.23%-6.37%). Trace elements such as Au, Te, Bi, Pb and Ag were more enriched in Lo-Ⅱ.CONCLUSIONS: Lo-Ⅱ is the most important gold-bearing mineral. The changes of temperature and sulfur fugacity lead to the precipitation of loellingite and native gold. Native gold is precipitated by remobilization and migration of “invisible gold” in early arsenopyrite and loellingite.

关 键 词：金富集机制 电子探针 电感耦合等离子体质谱法 毒砂 斜方砷铁矿 微量元素 浩尧尔忽洞金矿床 

分 类 号：O657.63[理学—分析化学]