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Fractional crystallization-induced variations in sulfides from the Noril’sk-Talnakh mining district (polar Siberia, Russia)

Duran Charley J., Barnes Sarah-Jane, Pleše Pia, Prašek Marko Kudrna, Zientek Michael L. et Pagé Philippe. (2017). Fractional crystallization-induced variations in sulfides from the Noril’sk-Talnakh mining district (polar Siberia, Russia). Ore Geology Reviews, 90, p. 326-351.

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URL officielle: https://doi.org/10.1016/j.oregeorev.2017.05.016

Résumé

The distribution of platinum-group elements (PGE) within zoned magmatic ore bodies has been extensively studied and appears to be controlled by the partitioning behavior of the PGE during fractional crystallization of magmatic sulfide liquids. However, other chalcophile elements, especially TABS (Te, As, Bi, Sb, and Sn) have been neglected despite their critical role in forming platinum-group minerals (PGM). TABS are volatile trace elements that are considered to be mobile so investigating their primary distribution may be challenging in magmatic ore bodies that have been somewhat altered. Magmatic sulfide ore bodies from the Noril’sk-Talnakh mining district (polar Siberia, Russia) offer an exceptional opportunity to investigate the behavior of TABS during fractional crystallization of sulfide liquids and PGM formation as the primary features of the ore bodies have been relatively well preserved. In this study, new petrographic (2D and 3D) and whole-rock geochemical data from Cu-poor to Cu-rich sulfide ores of the Noril’sk-Talnakh mining district are integrated with published data to consider the role of fractional crystallization in generating mineralogical and geochemical variations across the different ore types (disseminated to massive). Despite textural variations in Cu-rich massive sulfides (lenses, veins, and breccias), these sulfides have similar chemical compositions, which suggests that Cu-rich veins and breccias formed from fractionated sulfide liquids that were injected into the surrounding rocks. Numerical modeling using the median disseminated sulfide composition as the initial sulfide liquid composition and recent DMSS/liq and DISS/liq predicts the compositional variations observed in the massive sulfides, especially in terms of Pt, Pd, and TABS. Therefore, distribution of these elements in the massive sulfides was likely controlled by their partitioning behavior during sulfide liquid fractional crystallization, prior to PGM formation. Our observations indicate that in the Cu-poor massive sulfides the PGM formed as the result of exsolution from sulfide minerals whereas in the Cu-rich massive sulfides the PGM formed by crystallization from late-stage fractionated sulfide liquids. We suggest that the significant amount of Sn-bearing PGM may be related to crustal contamination from granodiorite, whereas As, Bi, Te, and Sb were likely added to the magma along with S from sedimentary rocks. Large PGM that are scarce and randomly distributed may account for most of the whole-rock Pt budget. Based on our results, we propose a holistic genetic model for the formation of the magmatic sulfide ore bodies of the Noril’sk-Talnakh mining district.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:90
Pages:p. 326-351
Version évaluée par les pairs:Oui
Date:Novembre 2017
Sujets:Sciences naturelles et génie > Sciences naturelles > Sciences de la terre (géologie, géographie)
Département, module, service et unité de recherche:Départements et modules > Département des sciences appliquées > Unité d'enseignement en sciences de la Terre
Mots-clés:Noril’sk-Talnakh, fractional crystallization, magmatic sulfide liquids, Ni-Cu-PGE deposits, high-resolution X-ray computed, tomography, geochemical modeling
Déposé le:02 avr. 2019 23:52
Dernière modification:02 avr. 2019 23:52
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