造山型金矿床黄铁矿微量元素对成矿机制的指示  

Trace elements in pyrite from orogenic gold deposits:Implications for metallogenic mechanism

作　　者：曹根深 张宇 陈华勇[1,2,4] CAO GenShen;ZHANG Yu;CHEN HuaYong(Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;College of Earth and Planetary Science,University of Chinese Academy of Science,Beijing 100049,China;MOE Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,School of Geoscience and Info-physics,Central South University,Changsha 410083,China;Guangdong Provincial Key Laboratory of Mineral Physics and Materials,Guangzhou 510640,China)

机构地区：[1]中国科学院广州地球化学研究所,中国科学院矿物学与成矿学重点实验室,广州510640 [2]中国科学院大学地球与行星科学学院,北京100049 [3]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,长沙410083 [4]广东省矿物物理与材料研究开发重点实验室,广州510640

出　　处：《岩石学报》2023年第8期2330-2346,共17页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2022YFC2903601);湖南省科技创新计划项目(2021RC4055);广东省科技计划项目(2020B1212060055)联合资助

摘　　要：黄铁矿作为重要的金属硫化物,在各类金矿床中广泛产出,其微量元素特征被广泛应用于成矿流体物理化学性质的反演、成矿过程和矿床成因的限定。造山型金矿床作为全球金资源的主要提供者,其黄铁矿微量元素被广泛研究,但多局限于矿床个例的精细解剖与应用,缺乏对已有数据的综合统计分析。为此,本文广泛收集了前人发表的67个造山型金矿床黄铁矿微量元素数据4092组,开展了相关的数据统计分析,以此揭示造山型金矿床的成矿流体特征及其成矿机制。分析结果表明,造山型金矿床中黄铁矿Co/Ni比值(0.2~1.5)暗示了其流体以变质流体来源为主;但少部分样品具有低Cu/Zr和高Ni、Cr的特征,表明其成矿流体也可能与幔源流体相关;根据黄铁矿Se温度计算出的造山型金矿床的成矿温度峰值接近或高于350℃,这与前人认为该类矿床的成矿温度(200~350℃)有所差异,说明在低Se条件下这种温度计的计算结果具有不确定性;造山型金矿的黄铁矿Te含量(0.320×10^(-6)~7.07×10^(-6))以及Cu/Au比值(1.3~60.2)表明流体在迁移过程主要处于还原环境。此外,造山型金矿中黄铁矿的As/Sb、Ag/Co比值表明流体沸腾是Au沉淀的主要机制,Se/Te和Se/Ge比值则表明流体与大气降水的混合对于这类矿床的Au沉淀也起到了重要作用;而其黄铁矿的高孔隙度以及Au与低熔点亲铜元素的弱相关性表明造山型金矿中赋存的不可见金需要通过溶解再沉淀过程来实现其Au的活化迁移和再富集。本文黄铁矿微量元素大数据分析结果表明造山型金矿床的成矿机制并非由单一因素控制,且其流体来源多样,这一发现对于造山型金矿床的矿产勘查具有一定的指示意义。Pyrite,one of the most important sulfides,is widely spread in various types of gold deposits,and its trace element geochemistry is extensively useful for revealing the physicochemical conditions of ore-forming fluid,and thus constraining the ore-forming process and deciphering the ore genesis of the gold deposits,especially the orogenic ones(the main provider of global gold resources).However,this application is only limited to the individual deposit,as a result,trace element data of pyrite from orogenic gold deposits are still lack of a comprehensive statistical meaning.This study collected the trace element data of pyrites from 67 worldwide orogenic gold deposits published(4092 data sets)to reveal their physicochemical conditions of the ore-forming fluids and metallogenetic mechanisms based on statistical analysis.The Co/Ni ratio(0.2~1.5)of pyrite in orogenic gold deposits implies that their fluids are primarily from the metamorphic sources,while minority samples have lower Cu/Zr ratios and higher Ni and Cr contents,which also provides support for the source of mantle-derived fluids.Calculated by selenium concentration,the main ore-forming temperature peak is close to or even higher than 350℃in orogenic gold deposits,which is slightly different from the previous research,i.e.,the accuracy of the Se thermometer may be questionable when the Se content is lower.The Te content(0.320×10^(-6)~7.07×10^(-6))and Cu/Au ratio(1.3~60.2)of the pyrite from orogenic gold deposits demonstrate a possible reducing environment during their mineralization.In addition,the As/Sb and Ag/Co ratios indicate that fluid boiling may be the important controller for gold precipitation of the orogenic gold deposits,while the Se/Te and Se/Ge ratios implicate that meteoric water mixing also plays an important role in its gold precipitation.Furthermore,the high porosity and weak correlation between low-melting-point chalcophile elements and gold in pyrite from orogenic gold deposits have proven that dissolution-reprecipitation reactions wer

关 键 词：造山型金矿床 黄铁矿 微量元素 沉淀机制 大数据统计 地球化学数据库 

分 类 号：P578.292[天文地球—矿物学] P618.51[天文地球—地质学]