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Generation of porphyry copper deposits by gas–brine reaction in volcanic arcs


Porphyry copper deposits, that is, copper ore associated with hydrothermal fluids rising from a magma chamber, supply 75% of the world’s copper. They are typically associated with intrusions of magma in the crust above subduction zones, indicating a primary role for magmatism in driving mineralization. However, it is not clear that a single, copper-rich magmatic fluid could trigger both copper enrichment and the subsequent precipitation of sulphide ore minerals within a zone of hydrothermally altered rock. Here we draw on observations of modern subduction zone volcanism to propose an alternative process for porphyry copper formation. We suggest that copper enrichment initially involves metalliferous, magmatic hyper-saline liquids, or brines, that exsolve from large, magmatic intrusions assembled in the shallow crust over tens to hundreds of thousands of years. In a subsequent step, sulphide ore precipitation is triggered by the interaction of the accumulated brines with sulphur-rich gases, liberated in short-lived bursts from the underlying mafic magmas. We use high-temperature and high-pressure laboratory experiments to simulate such gas–brine interactions. The experiments yield copper–iron sulphide minerals and hydrogen chloride gas at magmatic temperatures of 700–800 °C, with textural and chemical characteristics that resemble those in porphyry copper deposits. We therefore conclude that porphyry copper ore forms in a two-stage process of brine enrichment followed by gas-induced precipitation.

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Figure 1: Coexisting fluid inclusions trapped in fractured quartz from sulphur-free dacite experiment, M7.
Figure 2: Run product from ‘porphyry in a capsule’ experiment, M4.
Figure 3: Comparison of experimental and natural mineralization textures.
Figure 4: Gas–brine reaction model for PCD formation.


  1. 1

    Hedenquist, J. W. & Lowenstern, J. B. The role of magmas in the formation of hydrothermal ore deposits. Nature 370, 519–527 (1994).

    Article  Google Scholar 

  2. 2

    Sillitoe, R. H. Porphyry copper systems. Econ. Geol. 105, 3–41 (2010).

    Article  Google Scholar 

  3. 3

    Cline, J. S. & Bodnar, R. J. Can economic porphyry copper mineralization be generated by a typical calc-alkaline melt? J. Geophys. Res. 96, 8113–8126 (1991).

    Article  Google Scholar 

  4. 4

    Landtwing, M. R. et al. Copper deposition during quartz dissolution by cooling magmatic–hydrothermal fluids: The Bingham porphyry. Earth Planet. Sci. Lett. 235, 229–243 (2005).

    Article  Google Scholar 

  5. 5

    Weis, P., Driesner, T. & Heinrich, C. A. Porphyry-copper ore shells form at stable pressure–temperature fronts within dynamic fluid plumes. Science 338, 1613–1616 (2012).

    Article  Google Scholar 

  6. 6

    Halter, W. E., Heinrich, C. A. & Pettke, T. Magma evolution and the formation of porphyry Cu–Au ore fluids: Evidence from silicate and sulfide melt inclusions. Mineral. Deposita 39, 845–863 (2005).

    Article  Google Scholar 

  7. 7

    Wilkinson, J. J. Triggers for the formation of porphyry ore deposits in magmatic arcs. Nature Geosci. 6, 917–925 (2013).

    Article  Google Scholar 

  8. 8

    Richards, J. P. Giant ore deposits formed by optimal alignment and combination of geological processes. Nature Geosci. 6, 911–916 (2013).

    Article  Google Scholar 

  9. 9

    Crerar, D. A. & Barnes, H. L. Ore solution chemistry V. Solubilities of chalcopyrite and chalcocite assemblages in hydrothermal solution at 200 to 350 °C. Econ. Geol. 71, 772–794 (1976).

    Article  Google Scholar 

  10. 10

    Hemley, J. J., Cygan, G. L., Fein, J. B., Robinson, G. R. & D’Angelo, W. M. Hydrothermal ore-forming processes in the light of studies in rock-buffered systems I:. Iron–copper–zinc–lead sulfide solubility relations. Econ. Geol. 87, 1–22 (1992).

    Article  Google Scholar 

  11. 11

    Lee, C. A. et al. Copper systematics in arc magmas and implications for crust–mantle differentiation. Science 336, 64–68 (2012).

    Article  Google Scholar 

  12. 12

    Edmonds, M. New geochemical insights into volcanic degassing. Phil. Trans. R. Soc. A 366, 4559–4579 (2008).

    Article  Google Scholar 

  13. 13

    Shinohara, H. Exsolution of immiscible vapor and liquid phases from a crystallizing silicate melt: Implications for chlorine and metal transport. Geochim. Cosmochim. Acta 58, 5215–5221 (1994).

    Article  Google Scholar 

  14. 14

    Hattori, K. H. & Keith, J. D. Contribution of mafic melt to porphyry copper mineralization: Evidence from Mount Pinatubo, Philippines, and Bingham Canyon, Utah, USA. Mineral. Deposita 36, 799–806 (2001).

    Article  Google Scholar 

  15. 15

    Wallace, P. J. Volatiles in subduction zone magmas: Concentrations and fluxes based on melt inclusion and volcanic gas data. J. Volcanol. Geotherm. Res. 140, 217–240 (2005).

    Article  Google Scholar 

  16. 16

    Christopher, T., Edmonds, M., Humphreys, M. C. S. & Herd, R. A. Volcanic gas emissions from Soufrière Hills Volcano, Montserrat 1995–2009, with implications for mafic magma supply and degassing. Geophys. Res. Lett. 37, LE00E04 (2010).

    Article  Google Scholar 

  17. 17

    Lesne, P. et al. Experimental simulation of closed-system degassing in the system basalt–H2O–CO2–S–Cl. J. Petrol. 52, 1737–1762 (2011).

    Article  Google Scholar 

  18. 18

    Keppler, H. The distribution of sulfur between haplogranitic melts and aqueous fluids. Geochim. Cosmochim. Acta 74, 645–660 (2010).

    Article  Google Scholar 

  19. 19

    Pyle, D. M. & Mather, T. A. Halogens in igneous processes and their fluxes to the atmosphere and oceans from volcanic activity: A review. Chem. Geol. 263, 110–121 (2009).

    Article  Google Scholar 

  20. 20

    Bodnar, R. J., Lecumberri-Sanchez, P., Moncada, D. & Steele-MacInnis, M. Treatise on Geochemistry 2nd edn, Ch. 13.5, 119–142 (Elsevier, 2014).

    Book  Google Scholar 

  21. 21

    Simon, A. C., Pettke, T., Candela, P. A., Piccoli, P. M. & Heinrich, C. A. Copper partitioning in a melt–vapor–brine–magnetite–pyrrhotite assemblage. Geochim. Cosmochim. Acta 70, 5583–5600 (2006).

    Article  Google Scholar 

  22. 22

    Tattitch, B. C., Candela, P. A., Piccoli, P. M. & Bodnar, R. J. Copper partitioning between felsic melt and H2O–CO2 bearing saline fluids. Geochim. Cosmochim. Acta 148, 81–99 (2014).

    Article  Google Scholar 

  23. 23

    Borisova, A. Y. et al. Trace element geochemistry of the 1991 Mt. Pinatubo silicic melts, Philippines: Implications for ore-forming potential of adakitic magmatism. Geochim. Cosmochim. Acta 70, 3702–3716 (2006).

    Article  Google Scholar 

  24. 24

    Blundy, J., Cashman, K. & Berlo, K. Evolving magma storage conditions beneath Mount St. Helens inferred from chemical variations in melt inclusions from the 1980–1986 and current eruptions. USGS Prof. Pap. 1750, 755–790 (2008).

    Google Scholar 

  25. 25

    Kasai, K., Sakagawa, Y., Miyazaki, S., Akaku, K. & Uchida, T. Supersaline and metal-rich brine obtained from the Quaternary Kakkonda Granite by NEDO WD-1a in the Kakkonda geothermal field, Japan. Mineral. Deposita 33, 298–301 (1998).

    Article  Google Scholar 

  26. 26

    Valori, A., Cathelineau, M. & Marignac, C. Early fluid migration in a deep part of the Larderello geothermal field: A fluid inclusion study of the granite sill from well Monteverdi 7. J. Volcanol. Geotherm. Res. 51, 115–131 (1992).

    Article  Google Scholar 

  27. 27

    Paulatto, M. et al. Upper crustal structure of an active volcano from refraction/reflection tomography, Montserrat, Lesser Antilles. Geophys. J. Int. 180, 685–696 (2009).

    Article  Google Scholar 

  28. 28

    Kagiyama, T., Utada, H. & Yamamoto, T. Magma ascent beneath Unzen Volcano, SW Japan, deduced from the electrical resistivity structure. J. Volcanol. Geotherm. Res. 89, 35–42 (1999).

    Article  Google Scholar 

  29. 29

    Müller, A. & Haak, V. 3-D modeling of the deep electrical conductivity of Merapi volcano (Central Java): Integrating magnetotellurics, induction vectors and the effects of steep topography. J. Volcanol. Geotherm. Res. 138, 205–222 (2004).

    Article  Google Scholar 

  30. 30

    Seo, J. H., Guillong, M. & Heinrich, C. A. The role of sulfur in the formation of magmatic–hydrothermal copper–gold deposits. Earth Planet. Sci. Lett. 282, 323–328 (2009).

    Article  Google Scholar 

  31. 31

    Seo, J. H. & Heinrich, C. A. Selective copper diffusion into quartz-hosted vapor inclusions: Evidence from other host minerals, driving forces, and consequences for Cu–Au ore formation. Geochim. Cosmochim. Acta 113, 60–69 (2013).

    Article  Google Scholar 

  32. 32

    Burgisser, A. & Scaillet, B. Redox evolution of a degassing magma rising to the surface. Nature 445, 194–197 (2007).

    Article  Google Scholar 

  33. 33

    Newton, R. C. & Manning, C. E. Solubility of anhydrite, CaSO4, in NaCl–H2O solutions at high pressures and temperatures: Applications to fluid–rock interaction. J. Petrol. 46, 701–716 (2005).

    Article  Google Scholar 

  34. 34

    Blundy, J., Cashman, K., Rust, A. & Witham, F. A case for CO2-rich arc magmas. Earth Planet. Sci. Lett. 290, 289–301 (2010).

    Article  Google Scholar 

  35. 35

    Mei, Y., Sherman, D. M., Liu, W. & Brugger, J. Ab initio molecular dynamics simulation and free energy exploration of copper(I) complexation by chloride and bisulfide in hydrothermal fluids. Geochim. Cosmochim. Acta 102, 45–64 (2013).

    Article  Google Scholar 

  36. 36

    Giggenbach, W. F. in Geochemistry of Hydrothermal Ore Deposits 3rd edn (ed. Barnes, H. L.) Ch. 15, 737–796 (Wiley, 1997).

    Google Scholar 

  37. 37

    Seward, T. M. & Barnes, H. L. in Geochemistry of Hydrothermal Ore Deposits 3rd edn (ed. Barnes, H. L.) Ch. 9, 435–486 (Wiley, 1997).

    Google Scholar 

  38. 38

    Frank, M. R., Candela, P. A. & Piccoli, P. M. K–feldspar–muscovite–andalusite–quartz–brine phase equilibria: An experimental study at 25 to 60 MPa and 400 to 550 °C. Geochim. Cosmochim. Acta 62, 3717–3727 (1998).

    Article  Google Scholar 

  39. 39

    John, D. A. (ed.) Porphyry Copper Deposit Model: Chapter B of Mineral Deposit Models for Resource Assessment Report 20105070B (USGS, 2010).

  40. 40

    Gustafson, L. B. Some major factors of porphyry copper genesis. Econ. Geol. 73, 600–607 (1978).

    Article  Google Scholar 

  41. 41

    Caricchi, L., Simpson, G. & Schaltegger, U. Zircons reveal magma fluxes in the Earth’s crust. Nature 511, 457–461 (2014).

    Article  Google Scholar 

  42. 42

    Frank, M. R. & Vaccaro, D. M. An experimental study of high temperature potassic alteration. Geochim. Cosmochim. Acta 83, 195–204 (2012).

    Article  Google Scholar 

  43. 43

    Crisp, J. Rates of magma emplacement and volcanic output. J. Volcanol. Geotherm. Res. 20, 177–211 (1984).

    Article  Google Scholar 

  44. 44

    Luhr, J. F., Carmichael, I. S. E. & Varekamp, J. C. The 1982 eruptions of El Chichón Volcano, Chiapas, Mexico: Mineralogy and petrology of the anhydrite-bearing pumices. J. Volcanol. Geotherm. Res. 23, 69–108 (1984).

    Article  Google Scholar 

  45. 45

    Plail, M., Edmonds, M., Humphreys, M. C. S., Barclay, J. & Herd, R. A. Geochemical evidence for relict degassing pathways preserved in andesite. Earth Planet. Sci. Lett. 386, 21–33 (2014).

    Article  Google Scholar 

  46. 46

    McCormick, B. T. et al. Volcano monitoring applications of the Ozone Monitoring Instrument. Geol. Soc. Lond. 380, 259–291 (2013).

    Article  Google Scholar 

  47. 47

    Blundy, J. D. & Sparks, R. S. J. Petrogenesis of mafic inclusions in granitoids of the Adamello Massif, Italy. J. Petrol. 33, 1039–1104 (1992).

    Article  Google Scholar 

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We acknowledge research funding from BHP Billiton, a Benjamin Meaker Visiting Professorship to J.M. and a Royal Society Wolfson Research Merit Award and ERC Advanced Grant (CRITMAG) to J.B. This work has benefited from discussions with J. Dilles, D. Dolejs, J. Eiler, C. Ford, R. Gold, R. Henley, C. Heinrich, J. Price, D. Sherman, E. Stolper, A. Webb and G. Yeates, as well as members of the Caltech PRG. We are grateful to M. Pistone for synthesizing the starting materials and R. Brooker and B. Buse for technical assistance.

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J.B. developed the hypothesis in conjunction with B.T. J.M. performed the experiments and analysed the run products. B.T. characterized the synthetic fluid inclusions. A.G. made observations of the Don Manuel core. J.B. wrote the first draft of the manuscript; all authors assisted in producing the final version.

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Correspondence to J. Blundy.

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Blundy, J., Mavrogenes, J., Tattitch, B. et al. Generation of porphyry copper deposits by gas–brine reaction in volcanic arcs. Nature Geosci 8, 235–240 (2015).

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