青海东昆仑果洛龙洼金矿床东区Ⅰ矿体群稀土元素地球化学  

REE geochemistry of No.1 ore body group of Guoluolongwa Au deposit,East Kunlun Orogenic belt,Qinghai Province,China

作　　者：刘心开[1] 高建国[1] 周家喜[2] 

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [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550002

出　　处：《地球化学》2013年第2期131-142,共12页Geochimica

基　　金：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开放基金项目(2011001);山东黄金集团科研项目(201122010100)

摘　　要：位于东昆仑东段昆中断裂的果洛龙洼金矿，为一具有大型远景的金矿床，是沟里金矿化集中区中造山带型金矿床的典型代表。根据对I矿体群深入系统的野外地质考察和显微镜下观察结果，本文将矿化分为石英脉型、蚀变岩（强硅化）型、千枚岩（弱硅化）型和破碎带型等四大类（其中石英脉型和蚀变岩型最为主要），并对这四类矿石的分布特征、矿物组合、结构构造和围岩蚀变等进行了系统的描述。借助电感耦合等离子体质谱（ICP-MS）对不同类型矿石进行稀土元素含量分析，结果显示全部样品的轻、重稀土元素分异特征明显（LREE／HREE=4.52～16.82），轻稀土元素和重稀土元素内部分异不显著，为典型的轻稀土富集型。具有Eu负异常（Eu／Eu＊=0.56～1.00）和ce正异常（Ce／Ce＊=0.95～1.61）特征，表明成矿流体本身亏损Eu或来源于亏损Eu的源区，且成矿时处于还原环境。不同类型矿石与赋矿围岩及含金黄铁矿稀土组成特征和分布模式对比，结果显示成矿流体中的稀土元素主要继承于围岩，并具有由石英脉型向蚀变岩型，再向千枚岩型演化的特征。Guoluolongwa Au deposit, a large prospective and typical orogenic Au deposit of Gouli Au metallogenic district, is located in the Kunzhong fault of East Kunlun Orogenic belt. In this paper, the geological characteristics of No.1 ore body group were investigated by field geological survey and detected under microscope systematically. Based on detailed observation, the ore types are divided into four groups： quartz vein type, altered rocks type （strongly silicification）, phyllite type （weakly silicification） and oxidized type, the main of which are the quartz vein and altered rock types. The distribution, mineral assemblage, texture and structure, wall-rock alteration of the four types were systematically described, of which the REE contents were analyzed by inductively coupled plasma mass spectrometry （ICP-MS）. The results show that all samples have light rare earth element （LREE） contents higher than heavy rare earth elements （HREE） （LREE/HREE=4.52-16.82）, whereas no obvious fractionation in the internal LREE and HREE. All samples have negative Eu anomaly （Eu/Eu＊=0.56-1.00） and positive Ce anomaly （Ce/Ce＊=0.95-1.61）, indicating that the ore-forming fluids are Eu depleted and/or originated from a Eu depleted source. The mineralization formed under a reducing condition. Comparision of the ores, host rocks and Au-enriched pyrite, suggests that the REE in the ore-forming fluids is inherited form the host rocks, and the evolution is from quartz vein to altered rock, then to phyllite types.

关 键 词：矿化类型 REE地球化学 成矿流体来源 果洛龙洼金矿床 青海省 

分 类 号：P595[天文地球—地球化学] P611[天文地球—地质学]