地学前缘 ›› 2010, Vol. 17 ›› Issue (1): 139-.

• 论文 • 上一篇    下一篇

新疆北部镁铁-超镁铁质岩的PGE成矿问题

  

  1. 1北京矿产地质研究院, 北京 100012
    2中国科学院 地质与地球物理所 矿产资源研究重点实验室, 北京 100029
  • 出版日期:2010-01-28 发布日期:2010-01-28
  • 作者简介:王玉往(1965—),男,研究员,矿物学、岩石学、矿床学专业,矿床学与矿床地球化学、火成岩岩石学研究方向。Email: wyw@cnncm.com
  • 基金资助:

    国家重点基础研究发展计划“973”项目(2007CB411304,2001CB409806)

PGE metallogenesis related to maficultramafic complex in North Xinjiang.

  1. 1Beijing Institute of Geology for Mineral Resources, Beijing 100012, China
    2Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
  • Online:2010-01-28 Published:2010-01-28

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摘要：

铂族元素(PGE)矿化主要与镁铁超镁铁杂岩有关,成矿类型主要为岩浆型矿床,这类PGE矿床的形成主要依赖两个条件:一是岩浆中富含PGE;二是具备PGE从岩浆中分离和富集的机制,主要是在岩浆演化过程中硫达到饱和。新疆北部镁铁超镁铁质杂岩发育,并产有喀拉通克、黄山、黄山东、图拉尔根4个大型铜镍矿床和香山、土墩、葫芦、白石泉等中、小型铜镍矿,以及香山西、尾亚等中型钒钛磁铁矿矿床,但迄今尚未发现成型的PGE矿床。文中通过对PGE矿床的形成机制与镁铁超镁铁杂岩源区特征研究,探讨了北疆地区PGE矿床的成矿问题。综合分析认为,新疆北部后碰撞镁铁超镁铁质岩的岩石类型为经过了分离结晶形成的铁质岩石系列,是PGE矿床的有利容矿岩石;矿床的Sr、Nd、Pb、O、Os和S同位素和含矿岩石地球化学特征表明,铜镍硫化物矿床含矿岩浆在岩浆演化和成矿过程中有地壳物质加入并可导致硫化物熔离作用,说明在成矿机制上也存在形成岩浆型PGE矿化的条件。新疆北部PGE矿化微弱的原因可能在于该区广泛发育的亏损型地幔源(具正的εNd值特征),这一亏损型地幔可能部分源于洋壳熔融,与产于后碰撞造山带环境、发育于“洋壳”或“不成熟”陆壳基底之上有关,由此决定了原始岩浆为贫PGE的源区,因此不利于PGE的富集成矿。

关键词: 镁铁超镁铁质杂岩, PGE矿化, Nd同位素, 成矿机制, 新疆北部

Abstract:

 Platinum group elements (PGE) mineralization is mostly related to maficultramafic complex with dominant oreforming type of magmatic deposit. The formation of this type of PGE deposit mainly relies on two conditions: abundant PGE contents in magma, and advantageous mechanism of PGE enrichment and separation out of magma in which sulfur reached saturation during the magmatic evolution. Maficultramafic complex is widely developed in North Xinjiang, which produces four largescale coppernickel deposits like Kalatongke, Huangshan, Huangshan East and Tulargen and numerous small to mediumsized coppernickel deposits such as Xiangshan, Tudun, Hulu, Baishiquan and others, as well as Xiangshan West and Weiya mediumsized VTi magnetite deposits, but rarely forms PGE deposit. Based on the oreforming mechanism of PGE deposits and the characteristics of the magma source of maficultramafic complex, we have discussed some questions about PGE metallogenesis in North Xinjiang in this paper. The rock types of the postcollisional maficultramafic complex in North Xinjiang is ferrous rock series by fractional crystallization, a favorable rock type for PGEhosted. For the CuNi sulfide deposit, the participation of crustal material causes the sulfide liquation during the process of magmatic evolution and mineralization, which is evidenced by the characteristics of Sr, Nd, Pb, O, Os and S isotopes and lithogeochemistry, indicating the existence of oreforming mechanism for magmatic PGE deposit. The weak PGE mineralization in North Xinjiang may principally ascribe to widelydeveloped depletiontype mantle source (with positive values of εNd) that possibly derived from partial melting of waterrich oceanic crust, which is associated with postcollisional orogen setting and development on the “oceanic crust” or “immature continental crust” basement. It is the PGEpoor original magma source, disadvantageous to PGE mineralization.

Key words: maficultramafic complex, PGE mineralization, Nd isotope, oreforming

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