| 胶东三山岛金矿床黄铁矿As富集机制及其对金成矿作用的指示 |
| Received:February 18, 2021 Revised:April 21, 2021 点此下载全文 |
| 引用本文：XU Yang,LAN TingGuang,SHU Lei,HU HuanLong,CHEN YingHua,and WANG Hong.2021.Enrichment mechanisms of arsenic in pyrite from Sanshandao gold deposit (Jiaodong Peninsula, China) and implications for gold metallogenesis[J].Mineral Deposits,40(3):419~431 |
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| Author Name | Affiliation | E-mail | | XU Yang | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China | | | LAN TingGuang | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China | lantingguang@126.com | | SHU Lei | MNR Key Laboratory of Gold Mineralization Processes and Resources Utilization, Shandong Institute of Geological Sciences, Jinan 250013, Shandong, China | | | HU HuanLong | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China | | | CHEN YingHua | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China | | | and WANG Hong | State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China | |
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| 基金项目:本文得到国家自然科学基金（编号：41873048）和国家重点研发计划（编号：2016YFC0600105）联合资助 |
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| 中文摘要:胶东是中国最大的金矿集区，其金矿成因目前还存在较大争议。作为最重要的载金矿物，黄铁矿显微结构及元素-同位素组成能够很好地示踪成矿物质来源和成矿过程。利用SEM、EPMA和LA-ICP-MS微区原位分析方法对胶东代表性蚀变岩型金矿—三山岛金矿的黄铁矿开展详细的BSE显微结构以及As含量和S同位素耦合关系研究，发现矿区至少存在3种不同结构和As含量的黄铁矿：①含金石英-黄铁矿细脉中具交代残余结构的低As黄铁矿（Py-1），在BSE图像中显示暗色的核部（Py-1a）和亮色的边部（Py-1b），Py-1a和Py-1b的w（As）分别为48×10-6~524×10-6和183×10-6~1134×10-6，δ34S值分别为10.4‰~10.8‰和11.6‰~11.9‰；②含金石英-黄铁矿细脉中具韵律环带结构的高As黄铁矿（Py-2），在BSE图像中显示富含矿物包裹体并多孔的核部（Py-2a）以及很少含矿物包裹体的“干净”边部（Py-2b），Py-2a和Py-2b的w（As）分别为0.14%~0.31%和0.47%~0.97%；③含金石英-多金属硫化物细脉中具核边结构且As含量变化大的黄铁矿（Py-3），其核部Py-3a富含黄铜矿、闪锌矿等矿物包裹体并贫As，w（As）仅为1×10-6~10×10-6，δ34S值为4.2%~5.8‰，边部Py-3b几乎不含矿物包裹体但富As，w（As）为8877×10-6~17 839×10-6，δ34S值为7.7%~10.1‰。上述黄铁矿中，从Py-1a到Py-1b，w（As）和δ34S值缓慢升高，可能主要受水岩相互作用的控制；Py-2具韵律环带且核部多孔、多矿物包裹体，指示了较为剧烈的流体沸腾作用；Py-3a和Py-3b具有截然不同的w（As）和δ34S值，指示了外来富As流体的加入。这些过程有利于As和Au的进一步富集，多种形式的富As和Au机制表明胶东金矿存在复杂的矿化过程和物质来源，特别是流体在迁移过程中萃取围岩中的成矿物质不可忽视。 |
| 中文关键词:地球化学 黄铁矿原位分析 显微结构 富As机制 S同位素 三山岛金矿 胶东 |
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| Enrichment mechanisms of arsenic in pyrite from Sanshandao gold deposit (Jiaodong Peninsula, China) and implications for gold metallogenesis |
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| Abstract:Jiaodong Peninsula is the largest gold Province in China. How the huge amounts of gold were accumulated in such an area is still controversial. Pyrite is the most important Au-carrier mineral, the elemental and isotopic compositions of which, coupled with its microtexture, can well record the specific ore-forming processes and the origin of Au. In this study, SEM, EPMA and LA-(MC)-ICP-MS analyses were conducted on microtextures as well as As contents and S isotopic compositions of pyrite from the giant Sanshandong gold deposit. The results show that at least three types of pyrite occur: ① Low-As pyrite (Py-1) in the Au-bearing quartz-pyrite vein, which shows metasomatic relict texture. Under the BSE imaging, a dark relict core (Py-1a) is surrounded by a grey rim (Py-1b). The Py-1a has As contents of 48×10-6~524×10-6 and δ34S values of 10.4‰~10.8‰ while the Py-1b has As contents of 183×10-6~1134×10-6 and δ34S values of 11.6‰~11.9‰; ② High-As pyrite (Py-2) in the Au-bearing quartz-pyrite vein, which shows rhythmic zoning texture. Under the BSE imaging, the pyrite has a dark porous core containing abundant mineral inclusions (Py-2a) and a bright clean rim (Py-2b). The Py-2a and Py-2b have As contents of 0.14%~0.31% and 0.47%~0.97%, respectively; ③ Pyrite in the Au-bearing quartz-polymetallic sulfide vein (Py-3). This pyrite is characterized by core-rim texture, showing a dark As-poor core (Py-3a) and a grey As-rich rim (Py-3b). The Py-3a and Py-3b have As contents of 1×10-6~10×10-6 and 8877×10-6~17839×10-6, δ34S values of 4.2‰~5.8‰ and 7.7‰~10.1‰, respectively. The slight increase of As and δ34S from Py-1a and Py-1b was most likely induced by fluid-rock interaction. The rhythmic zoning texture of Py-2, coupled with its mine-ral inclusion-bearing and porous core, likely suggests a fluid boiling. The contrasted As and δ34S values between the Py-3a and Py-3b indicate the injection of another As-rich fluid. The above processes facilitate the As and Au to be further enriched, implying that complex ore-forming processes and multiple origins of ore-forming metals contributed to the giant gold mineralization. Especially, the fluids extracting ore-forming metals from wall rocks cannot be ignored. |
| keywords:geochemistry In situ analysis of pyrite microtexture enrichment mechanisms of As sulfur isotope Sanshandao gold deposit Jiaodong Peninsula |
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