地学前缘 ›› 2018, Vol. 25 ›› Issue (2): 280-298.DOI: 10.13745/j.esf.yx.2017-12-24

• 非主题来稿选登 • 上一篇    下一篇

新疆磁海Fe(-Co)矿床：两个系列幔源岩浆复合的热液矿床

王玉往，石煜，唐萍芝，李德东，王京彬，解洪晶   

  1. 1. 北京矿产地质研究院, 北京 100012
    2. 有色金属矿产地质调查中心, 北京 100012
  • 收稿日期:2016-12-27 修回日期:2017-05-12 出版日期:2018-03-15 发布日期:2018-03-15
  • 作者简介:王玉往(1965—)，男，研究员，主要从事矿床地质研究。E-mail:wyw@cnncm.com
  • 基金资助:
    国家自然科学基金项目(41372102)；国家重点基础研究发展计划“973”项目(2014CB440803)

The Cihai FeCo deposit, Xinjiang: a superimposed hydrothermal mineralization of two mantlederived magmatic series.

WANG Yuwang,SHI Yu,TANG Pingzhi,LI Dedong,WANG Jingbin,XIE Hongjing   

  1. 1. Beijing Institute of Geology for Mineral Resources, Beijing 100012, China
    2. China Nonferrous Metals Resource Geological Survey, Beijing 100012, China
  • Received:2016-12-27 Revised:2017-05-12 Online:2018-03-15 Published:2018-03-15

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摘要： 新疆东部的磁海是一个以Fe-Co组合为特色的矿床。对磁海矿区镁铁超镁铁岩的年代学和地质地球化学、矿床共生Co的地质特征、黄铁矿的成分特征等研究发现，磁海矿床是一个同期两个系列(即铜镍系列和钛铁系列)幔源岩浆作用复合的岩浆热液型矿床。铜镍系列主要形成了橄榄辉长岩、橄长岩、辉长岩和角闪辉长岩等深成侵入相，辉长岩锆石U-Pb年龄为(279.1±1.4) Ma；岩石以较高的m/f值(多数>1.5)为特征；同时，岩石具有较高的Cu、Ni、Co含量，并赋存有Cu-Ni-Co矿化体，表明该系列与矿床中Co的来源关系密切。钛铁系列以火山次火山作用为主，形成了玄武岩辉绿岩等喷出相和超浅成侵入相，玄武岩的锆石UPb年龄为(276.2±2.2) Ma；岩石以较低的m/f值(多数<1.5)为特征；岩石中Cu、Ni含量较低而TiO2含量较高，并赋存了磁海矿床主要的磁铁矿体，表明与矿床中Fe的来源密切相关。磁海矿床矿体和矿石地质特征表明，主要磁铁矿(Co)矿体的形成受控于热液作用，属于与基性超基性岩浆有关的热液矿床。对不同类型黄铁矿的产出特征及成分特征研究显示，Co的成矿是在磁铁矿成矿之后，(次)火山热液活动继续对与磁铁矿共生的黄铁矿进行交代，形成了含钴黄铁矿和其他钴矿物。也就是说，矿床中Fe和Co是两种来源两个阶段复合形成的，磁海矿床的FeCo复合成矿作用实质上是钛铁系列与铜镍系列岩浆的复合。

关键词: 新疆磁海, Fe-Co矿床, 复合成矿, 含钴黄铁矿, 镁铁超镁铁岩, 岩浆系列

Abstract:  The Cihai deposit in the Eastern Xinjiang is best known for its special Fe-Co metal assemblage. In this paper, we studied the chronology and geochemistry of maficultramafic rocks, geological characteristics of the symbiotic Co mineral and chemical composition of pyrite at the Cihai ore district, and concluded that the Cihai deposit was a superimposed magmatic hydrothermal deposit of two mantlederived magmatic series, i.e. Cu-Ni and Ti-Fe series. The Cu-Ni series produces plutonic rocks including olivine gabbro, troctolite, gabbro and hornblende gabbro with a zircon U-Pb age of 279.1±1.4 Ma for the gabbros. The rocks of Cu-Ni series have high m/f ratio (mostly higher than 1.5), contain high levels of Co, Ni and Cu, and host Cu-NiCo sulfide mineralized bodies, suggesting their proximity to Co source of the deposit. The Ti-Fe series produces extrusive and hypabyssal rocks including basalt and diabase, and yields a zircon U-Pb age of 276.2±2.2 Ma for basalt. The rocks of TiFe series have low m/f ratio (mostly lower than 1.5), contain low percentage of Ni and Cu but rich in TiO2, and host magnetite ore bodies, all indicating the series is close to Fe source of the deposit. The geological characteristics of orebody and ore suggest that the formation of the main magnetiteCo orebodies were controlled by hydrothermal mineralization, and the deposit may belong to a hydrothermal deposit related basicultrabasic magma. The occurrence and chemical composition of different pyrite types further reveal that the Co mineralization happened after magnetite mineralization, and that the metasomatism of pyrite by volcanicsubvolcanic hydrothermal mineralization formed the Cobearing pyrite and other cobalt minerals. In other words, Fe and Co deposits display complex mineralization from two sources and in two stagesthey are essentially the superposition of CuNi and Ti-Fe magma series.

Key words: Cihai, Xinjiang, FeCo deposit, metallogenic superimposition, Cobearing pyrite, maficultramafic rocks, magmatic series

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