内蒙古白乃庙铜-金-钼矿床侵入岩和围岩成因:岩石地球化学和Hf同位素的证据  

Origin of intrusive rock and surrounding rock in Bainaimiao Cu-Au-Mo deposit, Inner Mongolia: Evidences from geochemistry and Hf isotope characteristics

作　　者：高旭 周振华[1] 车合伟 马星华[1] 欧阳荷根[1] 陈宝全 刘国东 GAO Xu;ZHOU ZhenHua;CHE HeWei;MA XingHua;OUYANG HeGen;CHEN BaoQuan;LIU GuoDong(MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Science and Mineral Resources,China University of Geosciences,Beijing 100083,China;Huanggang Mining Co.,Ltd.,Inner Mongolia,Keshiketeng 016100,China)

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037 [2]中国地质大学地球科学学院,北京100083 [3]内蒙古黄岗矿业有限责任公司,克什克腾旗016100

出　　处：《矿床地质》2018年第2期420-440,共21页Mineral Deposits

基　　金：国家科技基础资源调查专项(编号:2017FY101300、2017FY101302)和中央公益性科研院所基本业务费项目(编号:K1314)的联合资助

摘　　要：白乃庙铜-金-钼矿是华北北缘中段的一个重要矿床,矿体主要赋存在早古生代白乃庙群绿片岩中,其成矿与花岗闪长斑岩密切相关。岩石地球化学特征显示,该区侵入岩花岗闪长斑岩以及石英闪长岩与起源于俯冲洋壳的埃达克岩的特征类似,岩浆在上升侵位过程中受到了明显的变质基底的混染作用。赋矿围岩绿片岩的原岩主要为中基性火山岩,锆石Hf同位素数据显示,白乃庙绿片岩、变质安山岩中锆石的εHf(t)变化范围为-4.64^+11.29之间,而白音都西群变质石英砂岩的εHf(t)为-4.30^+15.50,显示白乃庙地区围岩原岩源区物质主要来源于亏损地幔,并在侵位过程中受到了古老地壳基底的混染作用。2类岩石的二阶段Hf同位素模式年龄分别为693~2843 Ma和481~2363 Ma,峰值区间在700~1500 Ma,揭示了华北板块中-新元古代陆壳增生和构造热事件。矿床地质特征、岩石学和地球化学组成表明,白乃庙铜-金-钼矿床具有低氧逸度的特征,可能为还原性斑岩型矿床。The Bainaimiao Cu-Au-Mo Deposit is an important deposit in the Middle north margin of North China,its ore body is mainly in the Bainaimiao group greenschist and the mineralization is closely related to the granodiorite porphyry.The geochemical data shows that the characteristics of intrusive rocks which include granodiorite porphyry and quartz diorite are similar to adakites that originate from the subducted oceanic crust,and it is affected by the mixed infection of the metamorphic basement in the process of rising.The original rock of greenschist is basic-intermediate volcanic rocks and the zircon Hf isotopic data shows that the zirconεHf(t)values of the greenschist and Metamorphic andesite range from-4.64 to+11.29.Beyond that,the zirconεHf(t)values of the Baiyinduxi group metamorphic quartz sandstone range from-4.30 to+15.50.Combine both of that,it is known that the source material of the surrounding rock mainly comes from the depleted mantle and it undergoes contamination in the process of invasion by the ancient crustal basement.The two-stage model ages of two kinds of rocks are 693~2843 Ma and 481~2363 Ma and the peak interval is 700~1500 Ma,which shows the continental crust accretion and tectonic thermal events of the North China craton in the Meso-and Neo-proterozoic.Analysis from the view of petrology,the ore bearing magma of Bainaimiao Cu-Au-Mo Deposit has low oxygen fugacity,and from the geological features of the ore deposits,the low degree of oxidation is also reflected.Based on the previous studies,we can speculate that the deposit may be a reduced porphyry copper deposit.

关 键 词：地球化学 LU-HF同位素 埃达克岩 还原性斑岩矿床 白乃庙铜-金-钼矿床 

分 类 号：P618.41[天文地球—矿床学] P618.51[天文地球—地质学]