滇西北普朗超大型斑岩铜矿床外围斑岩体年代学、地球化学特征及其地质意义  

Geochronology and geochemical characteristics of porphyry bodies in the periphery of Pulang super-large porphyry copper deposit,NW Yunnan,SW China and their geological significances

作　　者：任翔 余海军 张传昱 江佳雯 苏肖宇 REN Xiang;YU Haijun;ZHANG Chuanyu;JIANG Jiawen;SU Xiaoyu(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming Yunnan 650093,China;Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,MNR,Kunming Yunnan 650051,China;Yunnan Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Kunming Yunnan 650051,China;Yunnan Geological Survey,Kunming Yunnan 650216,China;Faculty of Earth Resource,China University of Geosciences,Wuhan Hubei 430074,China)

机构地区：[1]昆明理工大学国土资源工程学院地球科学系,云南昆明650093 [2]自然资源部三江成矿作用及资源勘查利用重点实验室,云南昆明650051 [3]云南省三江成矿作用及资源勘查利用重点实验室,云南昆明650051 [4]云南省地质调查院,云南昆明650216 [5]中国地质大学资源学院,湖北武汉430074

出　　处：《矿物学报》2025年第1期111-133,共23页Acta Mineralogica Sinica

基　　金：国家自然科学基金项目(编号:42173026、U2344217、42302110);云南省基础研究计划项目(编号:202401BC070019、202301AT070019);云南省科技计划项目(编号:202305AT350004-3);云南省“兴滇英才”青年人才项目。

摘　　要：近年来,随着普朗超大型铜矿的投产,滇西北格咱地区已成为我国重要铜资源基地,经济社会效益显著,普朗外围的斑岩体研究及找矿成为该区下一步工作重点。本文对普朗北段和东段的石英二长斑岩和石英闪长玢岩开展了系统的岩相学、年代学和岩石化学研究。锆石U-Pb定年显示石英二长斑岩结晶年龄北段为(206.31±0.76) Ma、东段(211.00±0.64) Ma,与普朗主矿体含矿斑岩体年龄一致,属晚三叠世岩浆活动的产物。岩石化学组成上,石英闪长玢岩和石英二长斑岩二者总体富Al_(2)O_(3)、富碱(Na_(2)O+K_(2)O),显示出I型准铝-弱过铝质(A/CNK值为0.72~1.06)的高钾钙碱性系列特征;石英闪长玢岩相比石英二长斑岩具有更低的SiO_(2)、Mg O、Mg~#值、P_(2)O_(5)、Y、Yb_(N)和稀土元素总量,但二者具有一致的稀土配分模式,均表现为轻稀土元素富集,重稀土元素亏损,K、Ba、Rb等大离子亲石元素富集,Ti、P、Nb、Ta等高场强元素亏损,说明普朗外围中酸性侵入岩形成于与板片俯冲有关的弧环境,且早阶段的石英闪长玢岩显示出经典岛弧岩石特征,可能主要以板片部分熔融为主,而晚阶段的石英二长斑岩更接近埃达克质岩石特征,可能有下地壳部分熔融物质的参与。结合前人普朗主矿体含矿斑岩体研究成果资料,本研究认为普朗北段和东段石英二长斑岩和石英闪长玢岩形成的构造背景与普朗主矿体含矿斑岩体一致,与甘孜-理塘洋向西俯冲消减有关,具备岛弧斑岩型铜金矿床的成矿条件,矿化蚀变强烈,具有较好的找矿前景,值得进一步开展找矿工作。In recent years,with the production of the Pulang super-large porphyry copper deposit,the Geza area in the northwestern Yunnan has become an important base of copper resource production in China,with remarkable economic and social benefits.The research and mineral prospecting of copper resource in porphyry bodies in the periphery of Pulang Mine are of important further working issues in the area.In this paper,petrography,geochronology and geochemistry of quartz monzonite porphyry and quartz diorite porphyry bodies in the North and East Pulang blocks have been systematically studied.The LA-ICP-MS zircon U-Pb dating results show that crystallization ages of quartz monzonite porphyry bodies in the northern and eastern Pulang blocks are(206.31±0.76)Ma and(211.00±0.64)Ma,respectively.They are consistent with the age of main ore-bearing porphyry body in the Pulang deposit and those porphyries belong to the product of late Triassic magmatic activity.In terms of petrochemical composition,the quartz diorite and quartz monzonite porphyries are generally rich in Al2O3 and alkali(Na_(2)O+K_(2)O),with characteristics of the type-I quasi-aluminous to weak peraluminous(A/CNK=0.72-1.06)high potassium calc-alkaline series.Comparing to the quartz monzonite porphyry,the quartz diorite porphyry has relatively low contents of SiO_(2),MgO,P_(2)O_(5),Y,and REE,and YbN and Mg#,values.However,both of them have consistent REE distribution patterns,with enriched LREE relatively depleted HREE,and weakly negative Eu anomalies.Their trace elements are rich in K,Ba,Rb and other LILE,but depleted in P,Ti,Nb,Ta and other HFSE.It is indicated that those intermediate-acid intrusive rocks in the periphery of Pulang deposit could be formed in the plate-subduction related volcanic arc environment.The early-stage quartz diorite porphyry which has typical characteristics of arc rocks could be mainly formed by magma derived from the partial melting of slab,while the late-stage quartz monzonite porphyry which has similar characteristics of the adakitic

关 键 词：锆石U-PB年代学 岩石化学 岩相学 普朗外围 滇西北 

分 类 号：P58[天文地球—岩石学] P61[天文地球—地质学]