内蒙古中部乌兰陶勒盖铜镍矿床形成时代与岩浆源区  

Formation Ageand Magmatic Source of the Wulantaolegai Cu-Ni Depositin Central Inner Mongolia

作　　者：王佳新 焦建刚[1,2,3] 马云飞 李峰 高超 WANG Jiaxin;JIAO Jiangang;MA Yunfei;LI Feng;GAO Chao(School of Earth Science and Resources,Chang'an University,Xi'an,Shaanxi710054,China;Key Laboratory of Western China's Mineral Resources and Geological Engineering,Ministry of Education,Xi'an,Shaanxi710054,China;Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals,Xi'an,Shaanxi710054,China;Inner Mongolia Branch of China National Geological Exploration Center of Building Materials Industry,Hohhot,Inner Mongolia010010,China;Inner Mongolia Fourth of Geology and Mineral Resources Exploration Development Co,Ltd,Ulanqab,Inner Mongolia012000,China;Inner Mongolia No2 Geological and Mineral Exploration and Development Co,Ltd,Bayannur,Inner Mongolia015000,China)

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]西部矿产资源与地质工程教育部重点实验室,陕西西安710054 [3]西安市关键金属成矿与高效利用重点实验室,陕西西安710054 [4]中国建筑材料工业地质勘查中心内蒙古总队,内蒙古呼和浩特010010 [5]内蒙古第四地质矿产勘查开发有限责任公司,内蒙古乌兰察布012000 [6]内蒙古第二地质矿产勘查开发有限责任公司,内蒙古巴彦淖尔015000

出　　处：《现代地质》2024年第4期991-1012,共22页Geoscience

基　　金：国家自然科学基金项目(编号92162213);内蒙古自治区地质勘查基金项目(2020-KY05)。

摘　　要：内蒙古中部存在多条镁铁-超镁铁质成矿岩带,其中位于黄花滩—小南山镁铁-超镁铁质成矿岩带中的乌兰陶勒盖中型铜镍硫化物矿床是近年来区域镍找矿的新突破。然而目前关于该矿床的形成时代、岩浆源区与构造背景研究属空白,对其开展深入研究有利于实现区域镍成矿规律总结及下一步找矿部署。本文选择乌兰陶勒盖铜镍硫化物矿床中的辉长岩与煌斑岩开展了系统的LA-ICP-MS锆石U-Pb定年、Hf同位素组成、全岩元素与Sr-Nd同位素组成分析。结果表明,辉长岩206Pb/238U加权平均年龄为(270.8±3.2)Ma,煌斑岩锆石U-Pb年龄为251.5~250.9 Ma,依次对应于古亚洲洋最终闭合后、西伯利亚板块与华北克拉通碰撞后伸展两期构造事件。辉长岩SiO_(2)含量为47.29%~51.45%,Na2O+K2O含量为0.97%~3.08%,属于亚碱性系列。辉长岩有相对较高的(87Sr/86Sr)i(0.7199~0.7239)与较低的εNd(t)值(-12.18~-9.55),指示岩浆源区系EMⅡ型富集岩石圈地幔。煌斑岩具有较低的SiO_(2)含量(47.72%~52.15%)及高的K2O含量(4.47%~9.43%),属于钙碱性钾质、过钾质煌斑岩;富集大离子亲石元素(LILE)和轻稀土元素(LREE),亏损Nb、Ta和Ti等高场强元素(HFSE),εHf(t)均为负值(-20.0~-2.9),表现出富集型岩石圈地幔受到俯冲流体交代作用的特征。The newly discovered medium-scale Wulantaolegai copper-nickel sulfide deposit marks a significant breakthrough in nickel prospecting in central Inner Mongolia.Central Inner Mongolia hosts several important mafic and ultramafic metallogenic belts.The Wulantaolegai Cu-Ni deposit formed within the Huanghuatan and Xiaonanshan mineralization belt.To understand the formation age and tectonic setting of the deposit and its cor-relations with the metallogenic zone,we conducted LA-ICP-MS zircon U-Pb dating and Hf isotope analysis,whole-rock major and trace element geochemistry,and Sr-Nd isotope analyses of gabbro and lamprophyre in the mining area.The results show that the U-Pb age of the gabbro is 270.8±3.2 Ma,and U-Pb ages of the lam-prophyre are approximately 251.5-250.9 Ma.They recorded two stages of magmatic activity during the exten-sion following the collision between the Siberian Craton and the North China Craton.The gabbro shows a sub-alkaline tholeiite series with a SiO_(2) content of approximately 47.3%-51.5%and a Na2O+K2O content of ap-proximately 1.0%-3.1%.The high(87 Sr/86 Sr)i value of approximately 0.7199-0.7239 and lowεNd(t)value of approximately-12.18 to-9.55 suggest that the source of the magma may be EMⅡ-type enriched lithospheric mantle.A low SiO_(2) content of approximately 47.72%-52.15%and Na2O+K2O content of ap-proximately 4.47%-9.43%indicates that the lamprophyre belongs to the calc-alkaline potassium series.The peralkalic lamprophyre,enriched in LILE and LREE but depleted in HFSE(such as Nb,Ta and Ti),as well as its negativeεHf(t)of approximately-20.0--2.9,indicates an enriched lithospheric mantle metasoma-tized by subduction fluids.These research achievements provide valuable insights for ore prospecting in the regional mafic and ultramafic rock bodies.

关 键 词：形成时代 岩石成因 铜镍硫化物矿床 乌兰陶勒盖 

分 类 号：P597.1[天文地球—地球化学] P597.3[天文地球—地质学] P618.41P631.63