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Mineralium Deposita

, 43:791 | Cite as

Platinum-group minerals from the Jinbaoshan Pd–Pt deposit, SW China: evidence for magmatic origin and hydrothermal alteration

  • Christina Yan WangEmail author
  • Hazel M. Prichard
  • Mei-Fu Zhou
  • Peter C. Fisher
Article

Abstract

The Jinbaoshan Pt–Pd deposit in Yunnan, SW China, is hosted in a wehrlite body, which is a member of the Permian (∼260 Ma) Emeishan Large Igneous Province (ELIP). The deposit is reported to contain one million tonnes of Pt–Pd ore grading 0.21% Ni and 0.16% Cu with 3.0 g/t (Pd + Pt). Platinum-group minerals (PGM) mostly are ∼10 μm in diameter, and are commonly Te-, Sn- and As-bearing, including moncheite (PtTe2), atokite (Pd3Sn), kotulskite (PdTe), sperrylite (PtAs2), irarsite (IrAsS), cooperite (PtS), sudburyite (PdSb), and Pt–Fe alloy. Primary rock-forming minerals are olivine and clinopyroxene, with clinopyroxene forming anhedral poikilitic crystals surrounding olivine. Primary chromite occurs either as euhedral grains enclosed within olivine or as an interstitial phase to the olivine. However, the intrusion has undergone extensive hydrothermal alteration. Most olivine grains have been altered to serpentine, and interstitial clinopyroxene is often altered to actinolite/tremolite and locally biotite. Interstitial chromite grains are either partially or totally replaced by secondary magnetite. Base-metal sulfides (BMS), such as pentlandite and chalcopyrite, are usually interstitial to the altered olivine. PGM are located with the BMS and are therefore also interstitial to the serpentinized olivine grains, occurring within altered interstitial clinopyroxene and chromite, or along the edges of these minerals, which predominantly altered to actinolite/tremolite, serpentine and magnetite. Hydrothermal fluids were responsible for the release of the platinum-group elements (PGE) from the BMS to precipitate the PGM at low temperature during pervasive alteration. A sequence of alteration of the PGM has been recognized. Initially moncheite and atokite have been corroded and recrystallized during the formation of actinolite/tremolite, and then, cooperite and moncheite were altered to Pt–Fe alloy where they are in contact with serpentine. Sudburyite occurs in veins indicating late Pd mobility. However, textural evidence shows that the PGM are still in close proximity to the BMS. They occur in PGE-rich layers located at specific igneous horizons in the intrusion, suggesting that PGE were originally magmatic concentrations that, within a PGE-rich horizon, crystallized with BMS late in the olivine/clinopyroxene crystallization sequence and have not been significantly transported during serpentinization and alteration.

Keywords

Platinum-group minerals Hydrothermal alteration Pt–Pd ores Jinbaoshan Emeishan Large Igneous Province China 

Notes

Acknowledgements

This study was supported by China National “973” program (2007C841/401) and a research grant from the Research Grant Council of Hong Kong, SAR, China (HKU7057/05P). Zongyong Zhang and Jingdong Qi from Yunbao Mining Company at Jinbaoshan are thanked for providing great assistance during the field work at Jinbaoshan. Thorough reviews of this manuscript by John F.W. Bowles greatly improved the quality of this paper. Editorial handling by Bernd Lehmann is gratefully acknowledged.

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Christina Yan Wang
    • 1
    • 3
    Email author
  • Hazel M. Prichard
    • 2
  • Mei-Fu Zhou
    • 1
  • Peter C. Fisher
    • 2
  1. 1.Department of Earth SciencesThe University of Hong KongHong KongChina
  2. 2.School of Earth and Ocean SciencesCardiff UniversityCardiffUK
  3. 3.Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhouChina

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