东昆仑那更康切尔沟银多金属矿床晚二叠世流纹斑岩年代学和地球化学特征研究  

Geochronology and geochemistry of the Late Permian rhyolite porphyry in the Nagengkangqieergou Ag-polymetallic deposit,East Kunlun Orogen,NW China

作　　者：谷子成 龙灵利[2] 王玉往[2] 祝新友[2] 李顺庭[2] 王新雨 童海奎 马财 代岩 GU Zicheng;LONG Lingli;WANG Yuwang;ZHU Xinyou;LI Shunting;WANG Xinyu;TONG Haikui;MA Cai;DAI Yan(School of Earth Science and Resources,China University of Geosciences,Beijing 100083;Beijing Institute of Mineral Geology Co.Ltd.,Beijing 100012;Geological Survey of Qinghai Province,Xining 810001)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]北京矿产地质研究院有限责任公司,北京100012 [3]青海省地质调查局,西宁810001

出　　处：《矿产勘查》2021年第4期919-933,共15页Mineral Exploration

基　　金：青海省省财政资金地质项目(编号:2019048001ky001)资助。

摘　　要：位于东昆仑造山带的那更康切尔沟银多金属矿床是近年来发现的一大型热液脉型矿床。本文研究发现矿区深部流纹斑岩中存在斑岩型Cu矿化,且获得该流纹斑岩LA-ICP-MS锆石U-Pb年龄为253.2±1.7 Ma,形成于晚二叠世。赋矿流纹斑岩SiO_(2)含量为75.56%~76.01%,Na_(2)O+K_(2)O含量为4.09%~7.68%,K_(2)O/Na_(2)O为0.92~11.78,A/CNK为1.05~2.41,属高硅、高钾钙碱性过铝质岩石。该流纹斑岩明显富集Rb、K等大离子亲石元素(LILE),亏损Nb、Ti、P等高场强元素(HFSE);稀土总量(ΣREE)为245×10^(-6)~265×10^(-6),轻重稀土元素分馏明显((La/Yb)_(N)=7.76~9.96),并表现出Eu负异常(δEu=0.03~0.38)。综合分析认为那更康切尔沟矿区可能存在多期岩浆活动,形成斑岩型和热液脉型叠加成矿,该认识对本矿区乃至区域上寻找与火山-次火山热液有关的多金属矿床,尤其是深部找矿工作具有重要的指导意义。The Nagengkangqieergou Ag-polymetallic deposit,located in the East Kunlun orogenic belt,is a large hydrothermal vein deposit discovered in recent years.In this study,porphyry Cu mineralization was found in the rhyolite porphyry in the deep part of the mining area.In this paper,the LA-ICP-MS zircon U-Pb age of the rhyolite porphyry with porphyry mineralization is 253.2±1.7 Ma,which was formed in the Late Permian.The content of SiO_(2) and Na_(2)O+K_(2)O in the ore-bearing rhyolite porphyry is 75.56%~76.01%and 4.09%~7.68%,respectively,while the ratio of K_(2)O/Na_(2)O and A/CNK is 0.92~11.78 and 1.05~2.41.It belongs to high-silicon,high-potassium calc-alkaline peraluminous to strong peraluminous rocks.The rhyolite porphyry is obviously enriched in large ion lithophile elements(LILE)such as Rb and K,and depleted in high field strength elements(HFSE)such as Nb,Ti and P;the total amount of rare earth(ΣREE)is 245×10^(-6)~265×10^(-6),and the light and heavy rare earth elements are significantly fractionated((LA/Yb)_(N)=7.76~9.96),and show a strong negative Eu anomaly(δEu=0.03~0.38).Comprehensive analysis suggests that there may be multiple periods of magmatic activity in the Nagengkangqieergou mining area,forming porphyry and hydrothermal vein superimposed metallogenic features.The understanding has important indications for searching for polymetallic deposits related to volcanic-secondary volcanic hydrothermal solution in the mining area and even in the region,especially for deep prospecting.

关 键 词：东昆仑 那更 锆石U-PB年代学 地球化学 热液脉型矿床 斑岩型矿床 

分 类 号：P581[天文地球—岩石学]