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TitrePlatinum group element residence sites in Ni-Mo-Zn-PGE mineralized black shales, Yukon
AuteurGadd, M G; Peter, J M; Jackson, S; Yang, Z
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 40, (2017), 2017.
LiensOnline - En ligne
Année2017
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160413
ÉditeurGeological Association of Canada-Mineralogical Association of Canada
RéunionGAC-MAC Joint Annual Meeting; Kingston; CA; mai 14-18, 2017
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Formatspdf
ProvinceYukon
Sujetsgîtes polymétalliques; nickel; zinc; platine; géochimie des terres rares; analyses de la roche, éléments de terres rares; roches hôtes; minéralisation; gersdorffite; millérite; sphalérite; barytine; quartz; analyses spectrométriques; Groupe de Road River ; Formation de Canol ; minéraux métalliques; géologie générale; géochimie; Dévonien
ProgrammeÉtude des gîtes de sulfures massifs volcaniques, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
Polymetallic metalliferous shales are an important global resource for Zn, Ni, Cu, Mo, Se, U, V, ± Cr, Co, Ag, Au, platinum group elements (PGE) and rare earth elements (REE). The deposits are typically thin (<10 cm) and laterally widespread, covering 1000s of km2. Yukon hosts some of the best examples in the World and the Nick Ni-Zn-Mo-PGE deposit is the best-known example in Canada. However, many basic questions remain unresolved regarding the formation of these deposits, including the host mineral(s) for the PGE. Our research aims to determine the residence and mineralogical associations of PGE and other elements in the Nick deposit and several other localities with similar mineralization.

Mineralization is constrained to a thin (<10 cm) layer that is located at the contact between the Cambrian to Middle Devonian Road River Group and the Middle to Upper Devonian Canol Formation. Within this layer, the maximum metal abundances are as follows: Ni (7.0 wt.%), Mo (0.33 wt.%), Zn (2.3 wt.%), Pt (511 ppb), Pd (202 ppb), Ir (10.9 ppb), Ru (12 ppb), Re (25.8 ppm), Se (0.57 wt.%) and As (1.1 wt.%). The semi-massive sulfides consist predominantly of vaesite (NiS2), pyrite and sphalerite, with lesser millerite (NiS) and gersdorffite (NiAsS). Gangue minerals are primarily quartz, barite, apatite and trace to minor K-(Ba) feldspar and pyrobitumen.

Vaesite shares mutual boundaries with pyrite, and typically forms 0.1 to 0.2 mm-thick encrustations on pyrite or occurs as minute grains within pyrite nodules. Less commonly, vaesite occurs as discrete, anhedral grains. Preliminary laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) trace element maps indicate that vaesite is the principle PGE host mineral; these data show the highest abundances of Ru (up to 1 ppm), Pd (up to 10 ppm), Os (up to 2 ppm) and Pt (up to 5 ppm) in vaesite, which suggest that PGE- and Ni-bearing sulphides were deposited coevally. Although Ir is present in relatively high abundances in the lithogeochemical data, our preliminary LA-ICP-MS data do not identify its host mineral, and the residence site(s) for Ir currently remain unresolved. Ongoing research will continue to investigate the nature and residence of PGE at the Nick deposit and other, similar types of deposits in Yukon. Our salient goal is to develop an internally consistent model that describes the striking metal enrichment within this regionally significant layer.
Résumé(Résumé en langage clair et simple, non publié)
Ce résumé décrit les recherches en cours sur les dépôts de schiste carbonaté polymétallique qui se trouvent au Yukon. La recherche vise à mieux comprendre la résidence minéralogique des métaux du groupe du platine. Ce travail contribue à notre compréhension de la façon dont ces dépôts énigmatiques se sont formés en déterminant où dans les roches les métaux économiquement importants résident.
GEOSCAN ID299841