云南格咱岛弧带欠虽铜矿石英闪长玢岩年代学、岩石地球化学特征及成岩成矿的制约  

Geochronological and geochemical characteristics of Qiansui quartz dioriteporphyrite in the Geza Arc,Yunnan Province,and constrairts on diagenesis and mineralization

作　　者：李喆[1] 李文昌[1,2] 刘学龙[1] 赖安琦 杨富成[1] LI Zhe;LI Wengchang;LIU Xuelong;LAI Anqi;YANG Fucheng(Kunming University of Science and Technology, Kunming 650093, Yunnan, China;Chengdu Geological Survey Center of China eological Survey, Chengdu, 610081, Sichuan, China)

机构地区：[1]昆明理工大学,云南昆明650093 [2]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《中国地质》2017年第3期541-555,共15页Geology in China

基　　金：国家自然科学基金项目(41502076);云南省科技领军人才培养计划项目(2013HA001);中国地质调查局项目(12120114013701);云南省教育厅面上项目"云南格咱岛弧成矿带斑岩型铜矿成矿系统研究";昆明理工大学省级人培项目(KKSY201421042)联合资助~~

摘　　要：欠虽铜矿床位于西南三江地区义敦岛弧南段的格咱岛弧中南部,是近年来该区新发现的铜多金属矿床,具有良好的找矿前景。目前该地区已发现若干印支期成矿事件中形成的中大型矿床,是中国重要的多金属矿集区。本文通过LA-ICP-MS锆石U-Pb定年方法对欠虽铜矿石英闪长玢岩进行了年代学研究,获得铜矿化石英闪长玢岩的形成年龄为(220.3±0.66)Ma(MSWD=0.99)。岩石地球化学特征研究表明,欠虽石英闪长玢岩具有富钠(K2O/Na2O为0.05~1.42,平均值为0.86)、准铝质(0.82~1.19,平均值为1.07)的特征,岩石富集轻稀土元素(LREE),轻重稀土元素分馏明显(LaN/YbN=19.6~28.8),富集大离子亲石元素(LILE,Ba、Th、U、Sr),亏损高场强元素(HFSF,Ta、Nb、Ce、P、Ti),属于典型的I型花岗岩。欠虽铜矿成矿岩体成岩时代发生在印支晚期,含矿斑岩的微量元素特征、构造背景及同位素特征反映欠虽岩体形成于岛弧环境,与格咱岛弧印支期洋壳的俯冲造山作用密切联系。通过地球化学特征及成岩成矿年代的研究,表明欠虽多金属矿的形成年限与甘孜—理塘洋壳俯冲造山作用时限相近,且与普朗铜矿、红山铜矿是同期次同源构造-岩浆演化的产物,这对探讨格咱岛弧构造-岩浆演化及成岩成矿作用的研究具有重要意义。The Indosinian Qianui copper polymetallic deposit discovered in recent years is located in the central and southernsegment of the eastern Geza porphyry belt of southern Yidun arc in Southwest China.A large number of indo-Chinese large-sizeore deposits were formed in the metallogenic area,which is hence an important polymetallic belt in China.In this paper,the authorsstudied the ages of the Qiansui quartz diorite porphyry with zircon LA-ICP-MS U-Pb dating method and obtained the formationage of the copper mineralized quartz diorite porphyry of220.3±0.66Ma(MSWD=0.99).Geochemical characteristics indicate thatQiansui ore-bearing quartz diorite porphyry is characterized by rich Na(K2O/Na2O=0.05-1.42,averagely0.86),metaluminousnature(0.82-1.19,averagely1.07),enrichment of light rare earth elements(LREE,Ba,Th,U,Sr),obvious REE fractionation(LaN/YbN=19.6-28.8),enrichment of large ion lithophile elements(LILE,Ba,Th,U,Sr),and depletion of high field strength elements(HFSF,Ta,Nb,Ce,P,Ti).The rock belongs to typical I-type granite.The ore-forming process of Qiansui metallogenic rock bodyoccurred in the late Indosinian,and the trace element characteristics,tectonic background and isotopic characteristics of the orebearingporphyry suggest that Qiansui rock was formed in an island arc environment,and that its formation was probably related tothe subduction of oceanic crust in Indosinian.The study of geochemical characteristics and petrogenetic age of Qiansui reveals thefixed formation age of Qiansui and the time limit of Ganzi-Litang oceanic crust subduction orogeny,suggesting that Pulang andHongshan copper deposits were the products of the evolution of magma structure in the same period.The results obtained by theauthors have important significance for the study of Gezan island arc tectonic magmatic evolution and petrogenetic mineralization.

关 键 词：关键字:石英闪长玢岩 锆石U-PB年龄 地球化学特征 岩石成因 格咱岛弧 

分 类 号：P59[天文地球—地球化学] P618.41[天文地球—地质学]