Mineralium Deposita

, Volume 39, Issue 2, pp 159–172 | Cite as

Compositional variations of olivine from the Jinchuan Ni–Cu sulfide deposit, western China: implications for ore genesis

  • Chusi LiEmail author
  • Zhanghua Xu
  • Sybrand A. de Waal
  • Edward M. Ripley
  • Wolfgang D. Maier


The Jinchuan Ni–Cu sulfide deposit is hosted by an elongated, olivine-rich ultramafic body that is divided by subvertical strike-slip faults into three segments (central, eastern, and western). The central segment is characterized by concentric enrichments of cumulus olivine crystals and interstitial sulfides (pyrrhotite–pentlandite–chalcopyrite intergrowth), whereas the eastern and western segments are characterized by an increase of sulfides toward the lower contacts. In all segments sulfides are concentrated at the expense of intercumulus silicates. Olivine re-crystallization is found to be associated with actinolite alteration in some samples. The compositional variations of primary olivine from the sulfide-poor samples can be explained by a small degree of olivine crystallization (<5%) from a basaltic magma followed by local re-equilibration of the olivine with up to 30% trapped silicate liquid. In the sulfide-bearing samples the compositions of primary olivine record the results of olivine-sulfide Fe–Ni exchange that occurred after the trapped silicate liquid crystallized. Our olivine data indicate that Ni in the original sulfide liquids increased inward in the central segment and laterally away from the lower contact in the eastern segment. Variations in the compositions of sulfide liquids are thought to result from fractional segregation of immiscible sulfide liquid from a basaltic magma in a staging chamber instead of in situ differentiation. High concentrations of olivine crystals (mostly >50 modal%) and sulfide (averaging ~5 wt%) in the rocks are consistent with the interpretation that the Jinchuan deposit was formed by olivine- and sulfide-laden magma successively ascending through a conduit to a higher, now-eroded, level. Sulfide enrichment toward the center in the central segment and toward the lower contact in the eastern and western segments may have, in part, resulted from flow differentiation and gravitational settling during magma ascent, respectively.


Jinchuan Magma conduit Ni Olivine Sulfide 



We thank Tong Zongli and Jinchuan NF Metals Ltd. for their assistance in field work. Comments from Steve Barnes and Finn Barrett on an earlier draft of this paper and reviews by Mei-Fu Zhou, Grant Cawthorn, and Associate Editor Peter Lightfoot are greatly appreciated. Financial support for this work was provided through a grant (EAR 0104580) from the National Science Foundation of the United States to C. Li and E.M. Ripley, through a postdoctoral fellowship from University of Pretoria to Z.H. Xu, and through a fund from the Center for Research on Magmatic Ore Deposits of the University of Pretoria to S.A. de Waal.


  1. Barnes SJ (1986) The effect of trapped liquid crystallization on cumulus mineral compositions in layered intrusions. Contrib Mineral Petrol 93:524–531Google Scholar
  2. Barnes SJ, Hill RET (2000) Metamorphism of komatiite-hosted Ni sulfide deposits. In: Spry PG, Marshall B, Frank MV (eds) Metamorphosed and metamorphogenic ore deposits. Soc Econ Geol Rev Econ Geol 11:203–215Google Scholar
  3. Barnes SJ, Naldrett AJ (1985) Geochemistry of the JM (Howland) Reef of the Stillwater Complex, Minneapolis Adit area, I. sulfide chemistry and sulfide–olivine equilibrium. Econ Geol 80:627–645Google Scholar
  4. Barnes SJ, Tang ZL (1999) Chrome spinels from the Jinchuan Ni–Cu sulfide deposit, Gansu province, People’s Republic of China. Econ Geol 94: 343–356Google Scholar
  5. Brenan JM (2003) Effects of f S2, f O2, temperature, and melt composition on the Fe–Ni exchange between olivine and sulfide liquid: implications for natural olivine-sulfide assemblages. Geochim Cosmochim Acta 67:2663–2681CrossRefGoogle Scholar
  6. Cawthorn RG (2002) The role of magma mixing in the genesis of PGE mineralization in the Bushveld Complex: thermodynamic calculations and new interpretations: a discussion. Econ Geol 97:663–666Google Scholar
  7. Chai G, Naldrett AJ (1992a) Characteristics of Ni–Cu–PGE mineralization and genesis of the Jinchuan deposit, northwest China. Econ Geol 47:1475–1495Google Scholar
  8. Chai G, Naldrett AJ (1992b) The Jinchuan Ultramafic Intrusion: cumulate of a high-Mg basaltic magma. J Petrol 33:277–303Google Scholar
  9. De Waal SA, Xu ZH, Li C, Mouri H (2003) Emplacement of dense, viscous crystal mushes, Jinchuan Ultramafic Intrusion, western China. Can Mineral (in press)Google Scholar
  10. Ghiorso MS, Sack RO (1995) Chemical mass transfer in magmatic processes. IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid–solid equilibria in magmatic systems at elevated temperatures and pressures. Contrib Mineral Petrol 119:197–212CrossRefGoogle Scholar
  11. Keays RR, Crocket JH (1970) A study of precious metals in the Sudbury Ni irruptive ores. Econ Geol 65:438–450Google Scholar
  12. Lesher CM, Keays RR (2002) Komatiite-associated Ni–Cu–(PGE) deposits: mineralogy, geochemistry, and genesis. In: Cabri LJ (ed) The geology, geochemistry, mineralogy, and mineral beneficiation of the platinum-group elements. Can Inst Mining Metall Petrol Spec Vol 54:579–617Google Scholar
  13. Li C, Naldrett AJ (1993) Sulfide capacity of magma: a quantitative model and its application to the formation of the sulfide ores at Sudbury. Econ Geol 88:1253–1260Google Scholar
  14. Li C, Barnes S-J, Mackovicky E (1996) Partitioning of Ni, Cu, Ir, Rh, Pt and Pd between monosulphide solid solution and sulphide liquid: effects of temperature and composition. Geochim Cosmochim Acta 60:1231–1238Google Scholar
  15. Li C, Ripley EM, Naldrett AJ (2003a) Compositional variations of olivine and sulfur isotopes in the Noril’sk and Talnakh intrusions, Siberia: implications for ore forming processes in dynamic magma conduits. Econ Geol 98:69–86Google Scholar
  16. Li C, Ripley EM, Mathez EA (2003b) The effect of S on the partitioning of Ni between olivine and silicate melt in MORB. Chem Geol 201:295–306Google Scholar
  17. Li C, Naldrett AJ, Coats CJA, Johannessen P (1992) Platinum, palladium, gold, and copper-rich stringers at the Strathcona Mine, Sudbury: their enrichment by fractionation of a sulfide liquid. Econ Geol 87:1584–1598Google Scholar
  18. Li C, Naldrett AJ, Ripley EM (2001a) Critical factors for the formation of a Ni–copper deposit in an evolved magmatic system: lessons from a comparison of the Pants Lake and Voisey’s Bay sulfide occurrences in Labrador, Canada. Miner Deposita 36:85–92CrossRefGoogle Scholar
  19. Li C, Maier WD, de Waal SA (2001b) The role of magma mixing in the genesis of PGE mineralization in the Bushveld Complex: thermodynamic calculations and new interpretations. Econ Geol 96:653–662Google Scholar
  20. Li C, Maier WD, de Waal SA (2001c) Magmatic Ni–Cu versus PGE deposits: contrasting genetic controls and exploration implication. South African J Geol 104:309–318Google Scholar
  21. Lightfoot PC, Keays RR, Doherty W (2001) Chemical evolution and origin of Ni sulfide mineralization in the Sudbury Igneous Complex, Ontario, Canada. Econ Geol 96:1855–1876Google Scholar
  22. Mancini F, Papunen H (2000) Metamorphism of Ni–Cu sulfides in mafic–ultramafic intrusions: the Svecofennian Sääksjärvi Complex, southern Finland. In: Spry PG, Marshall B, Frank MV (eds) Metamorphosed and metamorphogenic ore deposits. Soc Econ Geol Rev Econ Geol 11:217–231Google Scholar
  23. Naldrett AJ (1998) World-class Ni–Cu–PGE deposits: key factors in their genesis. Miner Deposita 34:227–240CrossRefGoogle Scholar
  24. Naldrett AJ, Lightfoot PC (1999) Ni–Cu–PGE deposits of the Noril’sk region, Siberia: their formation in conduits for flood basalt volcanism. In: Keays RR, Lesher CM, Lightfoot PC, Farrow CFG (eds) Dynamic processes in magmatic ore deposits and their application to mineral exploration. Geol Assoc Can Short Course Notes XIII:195–250Google Scholar
  25. Ripley EM, Li C (2003) Sulfur isotopic exchange and metal enrichment in the formation of magmatic Cu–Ni–(PGE) deposits. Econ Geol 98:635–641Google Scholar
  26. Roeder PL, Emslie RF (1970) Olivine–liquid equilibrium. Contrib Mineral Petrol 29:275–289Google Scholar
  27. Tang ZL (1990) Mineralization model of the Jinchuan sulfide Cu–Ni deposit (in Chinese). Modern Geol 4:55–64Google Scholar
  28. Tang ZL (1993) Genetic models of the Jinchuan Ni–copper deposit. In: Kirkham RV, Sinclair WD, Thorpe RI, Duke JM (eds) Mineral deposit modeling. Geol Assoc Can Spec Pap 40:389–401Google Scholar
  29. Tang ZL, Li WY (1995) The metallogenetic model and geological contrast on the Jinchuan platinum-bearing Ni–Cu sulfide deposit (in Chinese). Geological Publishing House, BeijingGoogle Scholar
  30. Tang ZL, Yang J, Xu S, Tao X, Li W (1992) Sm–Nd dating of the Jinchuan ultramafic rock body, Gansu, China (in Chinese). Chin Sci Bull 37:1988–1991Google Scholar
  31. Zhou M-F, Yang Z-X, Song X-Y, Keays RR, Lesher CM (2002) Magmatic Ni–Cu–(PGE) sulfide deposits in China. In: Cabri LJ (ed) The geology, geochemistry, mineralogy, and mineral beneficiation of the platinum-group elements. Can Inst Mining Metall Petrol Spec Vol 54:619–636Google Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Chusi Li
    • 1
    Email author
  • Zhanghua Xu
    • 2
  • Sybrand A. de Waal
    • 2
  • Edward M. Ripley
    • 1
  • Wolfgang D. Maier
    • 2
  1. 1.Department of Geological SciencesIndiana UniversityBloomingtonUSA
  2. 2.Centre for Research on Magmatic Ore Deposits, Department of Earth SciencesUniversity of PretoriaPretoria 0002South Africa

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