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Transport of metals and sulphur in magmas by flotation of sulphide melt on vapour bubbles


Emissions of sulphur1,2 and metals3,4 from magmas in Earth’s shallow crust can have global impacts on human society. Sulphur-bearing gases emitted into the atmosphere during volcanic eruptions affect climate5,6, and metals and sulphur can accumulate in the crust above a magma reservoir to form giant copper and gold ore deposits, as well as massive sulphur anomalies3,4,7,8. The volumes of sulphur and metals that accumulate in the crust over time exceed the amounts that could have been derived from an isolated magma reservoir2. They are instead thought to come from injections of multiple new batches of vapour- and sulphide-saturated magmas into the existing reservoirs1,4,9,10. However, the mechanism for the selective upward transfer of sulphur and metals is poorly understood because their main carrier phase, sulphide melt, is dense and is assumed to settle to the bottoms of magma reservoirs. Here we use laboratory experiments as well as gas-speciation and mass-balance models to show that droplets of sulphide melt can attach to vapour bubbles to form compound drops11 that float. We demonstrate the feasibility of this mechanism for the upward mobility of sulphide liquids to the shallow crust. Our work provides a mechanism for the atmospheric release of large amounts of sulphur, and contradicts the widely held assumption that dense sulphide liquids rich in sulphur, copper and gold will remain sequestered in the deep crust.

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Figure 1: Morphologies of compound drops.
Figure 2: Cross-sectional cartoon illustrating sulphide flotation in subvolcanic environments.
Figure 3: Cu versus Au for modelled and measured compositions of sulphides, fluids and ores at Alumbrera3,29.


  1. Wallace, P. J. Volcanic SO2 emissions and the abundance and distribution of exsolved gas in magma bodies. J. Volcanol. Geotherm. Res. 108, 85–106 (2001).

    Article  Google Scholar 

  2. Wallace, P. J. & Edmonds, M. The sulfur budget in magmas: Evidence from melt inclusions, submarine glasses, and volcanic gas emissions. Rev. Mineral. Geochem. 73, 215–246 (2011).

    Article  Google Scholar 

  3. 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. Depos. 39, 845–863 (2005).

    Article  Google Scholar 

  4. Nadeau, O., Williams-Jones, A. E. & Stix, J. Sulphide magma as a source of metals in arc-related magmatic hydrothermal ore fluids. Nature Geosci. 3, 501–505 (2010).

    Article  Google Scholar 

  5. Devine, J. D., Sigurdsson, H., Davis, A. N. & Self, S. Estimates of sulfur and chlorine yield to the atmosphere from volcanic eruptions and potential climatic effects. J. Geophys. Res. 89 B7, 6309–6325 (1984).

    Article  Google Scholar 

  6. Santer, B. D. et al. Volcanic contribution to decadal changes in tropospheric temperature. Nature Geosci. 7, 185–189 (2014).

    Article  Google Scholar 

  7. Hunt, J. P. Pophyry copper deposits. Econ. Geol. Monogr. 8, 192–206 (1991).

    Google Scholar 

  8. Halter, W. E., Pettke, T. & Heinrich, C. The origin of Cu/Au ratios in porphyry-type ore deposits. Science 296, 1844–1846 (2002).

    Article  Google Scholar 

  9. Edmonds, M. New geochemical insights into volcanic degassing. Phil. Trans. Math. Phys. Eng. Sci. 366, 4559–4579 (2008).

    Article  Google Scholar 

  10. Edmonds, M. et al. Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano. Geochem. Geophys. Geosys. 11, Q04005 (2010).

    Article  Google Scholar 

  11. Neeson, M. J., Tabor, R. F., Grieser, F., Dagastine, R. R. & Chan, D. Y. C. Compound sessile drops. Soft Matter 8, 11042–11050 (2012).

    Article  Google Scholar 

  12. Westrich, H. R. & Gerlach, T. M. Magmatic gas source for the stratospheric SO2 cloud from the June 15, 1991, eruption of Mount Pinatubo. Geology 20, 867–870 (1992).

    Article  Google Scholar 

  13. Gerlach, T. M., Westrich, H. R., Casadevall, T. J. & Finnegan, D. L. Vapour saturation and accumulation in magmas of the 1989–1990 eruption of Redoubt Volcano, Alaska. J. Volcanol. Geotherm. Res. 62, 317–337 (1994).

    Article  Google Scholar 

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

    Article  Google Scholar 

  15. Hattori, K. High-sulfur magma, a product of fluid discharge from underlying mafic magma: Evidence from Mount Pinatubo, Philippines. Geology 21, 1083–1086 (1996).

    Article  Google Scholar 

  16. Di Muro, A. et al. Pre-1991 sulfur transfer between mafic injections and dacite magma in the Mt. Pinatubo reservoir. J. Volcanol. Geotherm. Res. 175, 517–540 (2008).

    Article  Google Scholar 

  17. Pallister, J. S., Hoblitt, R. P., Meeker, G. P., Knight, R. J. & Siems, D. F. in Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines (eds Newhall, C. G. & Punongbayan, R. S.) 687–731 (Univ. Wash. Press, 2004).

    Google Scholar 

  18. Van Hoose, A. E., Streck, M. J., Pallister, J. S. & Wälle, M. Sulfur evolution of the 1991 Pinatubo magmas based on apatite. J. Volcanol. Geotherm. Res. 257, 72–89 (2013).

    Article  Google Scholar 

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

    Article  Google Scholar 

  20. Larocque, A. C. L., Stimac, J. A., Keith, J. D. & Huminicki, M. A. E. Evidence for open-system behavior in immiscible Fe–S–O liquids in silicate magmas: Implications for contributions of metals and sulfur to ore-forming fluids. Can. Mineral. 38, 1233–1249 (2000).

    Article  Google Scholar 

  21. Mungall, J. E. & Su, S. Interfacial tension between magmatic sulfide and silicate liquids: Constraints on kinetics of sulfide liquation and sulfide migration through silicate rocks. Earth Planet. Sci. Lett. 234, 135–149 (2005).

    Article  Google Scholar 

  22. Botcharnikov, R. E. et al. Behavior of gold in a magma at sulfide–sulfate transition: Revisited. Am. Mineral. 98, 1459–1464 (2013).

    Article  Google Scholar 

  23. Mungall, J. E. & Brenan, J. M. Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle–crust fractionation of the chalcophile elements. Geochim. Cosmochim. Acta 125, 265–289 (2014).

    Article  Google Scholar 

  24. Metrich, N., Schiano, P., Clocchiatti, R. & Maury, R. C. Transfer of sulfur in subduction settings: An example from Batan Island (Luzon volcanic arc, Philippines). Earth Planet. Sci. Lett. 167, 1–14 (1999).

    Article  Google Scholar 

  25. Timina, T. Y., Sharygin, V. V. & Golovin, A. V. Melt evolution during the crystallization of basanites of the Tergesh Pipe, Northern Minusinsk Depression. Geochem. Int. 44, 752–770 (2006).

    Article  Google Scholar 

  26. Dowling, S. E., Barnes, S. J., Hill, R. E. T. & Hicks, J. D. Komatiites and nickel sulfide ores of the Black Swan area, Yilgarn Craton, Western Australia. 2: Geology and genesis of the orebodies. Mineral. Depos. 39, 707–728 (2004).

    Article  Google Scholar 

  27. Godel, B. High-resolution X-ray computed tomography and its application to ore deposits: From data acquisition to quantitative three-dimensional measurements with case studies from Ni–Cu–PGE deposits. Econ. Geol. 108, 2005–2019 (2013).

    Article  Google Scholar 

  28. Gaillard, F., Scaillet, B. & Arndt, N. T. Atmospheric oxidation caused by a change in volcanic degassing pressure. Nature 478, 229–232 (2011).

    Article  Google Scholar 

  29. Ulrich, T., Günther, D. & Heinrich, C. A. Gold concentrations of magmatic brines and the metal budgets of porphyry copper deposits. Nature 399, 676–679 (1999).

    Article  Google Scholar 

  30. Rothman, D. H. et al. Methanogenic burst in the end-Permian carbon cycle. Proc. Natl Acad. Sci. USA 111, 5462–5467 (2014).

    Article  Google Scholar 

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J.E.M. and J.M.B. were supported by Discovery Grants from the Natural Sciences and Engineering Research Council of Canada; B.G. and S.J.B. were funded by the CSIRO Mineral Resources Research Flagship, F.G. was supported by the European Research Council (ERC project #279790).

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J.M.B. performed experiments; J.E.M. performed modelling of interfaces and metal mass balance and wrote the manuscript; B.G. performed CT scanning and related data reduction; F.G. performed gas-speciation modelling, S.J.B., J.M.B. and J.E.M. contributed to the original concept. All authors discussed the results and edited the manuscript.

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Correspondence to J. E. Mungall.

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The authors declare no competing financial interests.

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Mungall, J., Brenan, J., Godel, B. et al. Transport of metals and sulphur in magmas by flotation of sulphide melt on vapour bubbles. Nature Geosci 8, 216–219 (2015).

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