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Proc Natl Acad Sci U S A. 2017 Mar 07;114(10):2485-2490. doi: 10.1073/pnas.1611086114. Epub 2017 Feb 21.

Role of degassing of the Noril'sk nickel deposits in the Permian-Triassic mass extinction event.

Proceedings of the National Academy of Sciences of the United States of America

Margaux Le Vaillant, Stephen J Barnes, James E Mungall, Emma L Mungall

Affiliations

  1. Commonwealth Scientific and Industrial Research Organisation, Mineral Resources, Kensington, WA 6151 Australia; [email protected].
  2. Commonwealth Scientific and Industrial Research Organisation, Mineral Resources, Kensington, WA 6151 Australia.
  3. Department of Earth Sciences, University of Toronto, Toronto, ON M5S 3B1, Canada.
  4. Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada.

PMID: 28223492 PMCID: PMC5347598 DOI: 10.1073/pnas.1611086114

Abstract

The largest mass extinction event in Earth's history marks the boundary between the Permian and Triassic Periods at circa 252 Ma and has been linked with the eruption of the basaltic Siberian Traps large igneous province (SLIP). One of the kill mechanisms that has been suggested is a biogenic methane burst triggered by the release of vast amounts of nickel into the atmosphere. A proposed Ni source lies within the huge Noril'sk nickel ore deposits, which formed in magmatic conduits widely believed to have fed the eruption of the SLIP basalts. However, nickel is a nonvolatile element, assumed to be largely sequestered at depth in dense sulfide liquids that formed the orebodies, preventing its release into the atmosphere and oceans. Flotation of sulfide liquid droplets by surface attachment to gas bubbles has been suggested as a mechanism to overcome this problem and allow introduction of Ni into the atmosphere during eruption of the SLIP lavas. Here we use 2D and 3D X-ray imagery on Noril'sk nickel sulfide, combined with simple thermodynamic models, to show that the Noril'sk ores were degassing while they were forming. Consequent "bubble riding" by sulfide droplets, followed by degassing of the shallow, sulfide-saturated, and exceptionally volatile and Cl-rich SLIP lavas, permitted a massive release of nickel-rich volcanic gas and subsequent global dispersal of nickel released from this gas as aerosol particles.

Keywords: Noril'sk Ni–Cu–PGE deposits; Permian–Triassic mass extinction; sulfide flotation

References

  1. Proc Natl Acad Sci U S A. 2014 Apr 15;111(15):5462-7 - PubMed
  2. Sci Adv. 2015 Aug 28;1(7):e1500470 - PubMed

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