华北克拉通南缘槐树坪金矿床成矿机制:来自黄铁矿原位微区分析的制约  

The mineralization mechanism of the Huaishuping gold deposit in the southern margin of North China Craton:Constraints from in-situ micro-analysis of pyrite

作　　者：程南南 马毓民 侯泉林 石梦岩 潘结南[1] 亢怡萱 李剑斌 CHENG NanNan;MA YuMin;HOU QuanLin;SHI MengYan;PAN JieNan;KANG YiXuan;LI JianBin(School of Resources and Environment,Henan Polytechnic University,Jiaozuo 454003,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]河南理工大学资源环境学院,焦作454003 [2]中国科学院大学地球与行星科学学院,北京100049

出　　处：《岩石学报》2025年第4期1406-1423,共18页Acta Petrologica Sinica

基　　金：河南省自然科学基金项目(232300420437、232300420439);河南省高等学校重点科研项目(23A170009、23A170015);河南省科技攻关项目(242102320359)联合资助.

摘　　要：华北克拉通南缘小秦岭-(崤山)-熊耳山-(外方山)矿集区是我国中部地区重要的金-多金属成矿带。熊耳山地区槐树坪金矿床的矿体赋存于中元古界熊耳群火山岩地层中,受马超营断裂及其次级断裂构造的控制。本研究在基于野外地质调查及岩相、矿相学观察的基础上,借助扫描电子显微镜(SEM)、电子探针(EPMA)以及激光电感耦合等离子体质谱(LA-ICP-MS)等实验分析方法,对槐树坪金矿床中金的赋存状态及元素组成特征,黄铁矿的主、微量元素含量特征进行研究,从而探讨矿床成因以及金的成矿机制。实验及分析结果表明,槐树坪金矿Au主要有可见金和不可见金两种赋存形式,可见金主要以自然金(平均Au含量为97.374%)的形式存在,其次为银金矿(平均Au含量为80.019%);而不可见金则以固溶体金和纳米级金的形式赋存于黄铁矿中。EPMA结果显示黄铁矿S、Fe平均含量分别为53.717%和45.951%,S、Fe原子个数比大于2(nS/nFe>2),表明黄铁矿属于Fe亏损型。LA-ICP-MS分析结果表明,黄铁矿中Cu、Sb、Pb、Bi等元素主要以包裹体的形式存在。黄铁矿Co/Ni比值(1.37~395,平均57.2)大于1、Au/Ag比值(0.012~6,平均为0.832)大于0.5,黄铁矿δS-δFe和Co-Ni-As投图结果均显示槐树坪金矿属于岩浆热液型金矿床。黄铁矿As/Sb比值表明其在沸腾环境中沉淀。结合前人对熊耳山地区金矿床的流体包裹体、同位素以及成矿时代等的研究,本文认为流体沸腾是造成槐树坪金矿Au沉淀的主要机制。The Xiaoqinling-(Xiaoshan)-Xiong ershan-(Waifangshan) ore concentration area, located in the southern margin of the North China Craton (NCC), is an important gold-polymetallic metallogenic belt in central China. The ore body of Huaishuping gold deposit in Xiong ershan area occurs in the volcanic rock of Mesoproterozoic Xiong er Group, which is controlled by Machaoying fault and its secondary faults. This study based on the field geological survey, petrographic and mineralographic observation, with the help of Scanning Electron Microscopy (SEM), Electron Probe Micro Analyzer (EPMA) and Laser Ablation-Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS) experimental analysis methods to investigate the occurrence state and element composition characteristics of Au in Huaishuping gold deposit, the main and trace element content characteristics of pyrite, to explore the genesis of the deposit and the metallogenic mechanism of gold. Experiments and analysis results show that Au in Huaishuping gold deposit mainly exists in two forms: visible gold and invisible gold, the visible gold mainly exists in the form of natural gold (the average Au content is 97.374%), electrum (the average Au content is 80.019%), and the invisible gold occurs inside the pyrite in the form of solid solution gold and nano-sized gold. The EPMA results show that the average contents of S and Fe in pyrite are 53.717% and 45.951%, the ratio of S and Fe atoms is bigger than 2 (nS/nFe>2), indicating that pyrite belongs to Fe depletion type. The results of LA-ICP-MS analysis show that Cu, Sb, Pb, Bi and other elements are mainly occurring in pyrite in the form of inclusions. The Pyrite Co/Ni ratio (1.37~395, average 57.2) bigger than 1, Au/Ag ratio (0.012~6, average 0.832) bigger than 0.5, δ S- δ Fe and Co-Ni-As mapping all indicate that Huaishuping gold deposit belongs to magmatic hydrothermal gold deposit. The As/Sb ratio of pyrite (1.565~2670, averaged at 394) indicates that pyrite is precipitated in a boiling environment. Combined with previou

关 键 词：黄铁矿 金矿物 成矿机制 LA-ICP-MS 槐树坪金矿 

分 类 号：P575.1[天文地球—矿物学] P578.292[天文地球—地质学] P618.51