THE PLATINUM-GROUP MINERALS IN THE UPPER SECTION OF THE KEIVITSANSARVI Ni Cu PGE DEPOSIT, NORTHERN FINLAND

Gervilla, Fernando; Kojonen, K.

doi:10.2113/gscanmin.40.2.377

Cited by 69 publications

(27 citation statements)

References 34 publications

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“…The behaviour of PGE during low temperature alteration A major finding of this study is the presence of significant quantities of PGE held in solid solution within pyrite, a feature also documented within other Ni-Cu-PGE sulfide deposits (e.g., Oberthür et al 1997;Barkov et al 1997;Gervilla and Kojonen 2002;Cabri et al 2002Cabri et al , 2008Cabri et al , 2010Djon and Barnes 2012;Dare et al 2011;Piña et al 2012Piña et al , 2013. Within the GNPA member, the pyrite is (1) host to comparable concentrations of IPGEs as pyrrhotite and pentlandite ( Fig.…”

Section: Hydrothermal Interactionsupporting

confidence: 66%

Precious and base metal geochemistry and mineralogy of the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex, South Africa: implications for a multistage emplacement

2014

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The Grasvally Norite-Pyroxenite-Anorthosite (GNPA) member within the northern limb of the Bushveld Complex is a mineralized, layered package of mafic cumulates developed to the south of the town of Mokopane, at a similar stratigraphic position to the Platreef. The concentration of platinum-group elements (PGE) in base metal sulfides (BMS) has been determined by laser ablation inductively coupled plasma-mass spectrometry. These data, coupled with wholerock PGE concentrations and a detailed account of the platinum-group mineralogy (PGM), provide an insight into the distribution of PGE and chalcophile elements within the GNPA member, during both primary magmatic and secondary hydrothermal alteration processes. Within the most unaltered sulfides (containing pyrrhotite, pentlandite, and chalcopyrite only), the majority of IPGE, Rh, and some Pd occur in solid solution within pyrrhotite and pentlandite, with an associated Pt-As and Pd-Bi-Te dominated PGM assemblage. These observations in conjunction with the presence of good correlations between all bulk PGE and base metals throughout the GNPA member indicate the presence and subsequent fractionation of a single PGE-rich sulfide liquid, which has not been significantly altered. In places, the primary sulfides have been replaced to varying degrees by a low-temperature assemblage of pyrite, millerite, and chalcopyrite. These sulfides are associated with a PGM assemblage characterized by the presence of Pd antimonides and Pd arsenides, which are indicative of hydrothermal assemblages. The presence of appreciable quantities of IPGE, Pd and Rh within pyrite, and, to a lesser, extent millerite suggests these phases directly inherited PGE contents from the pyrrhotite and pentlandite that they replaced. The replacement of both the sulfides and PGM occurred in situ, thus preserving the originally strong spatial association between PGM and BMS, but altering the mineralogy. Precious metal geochemistry indicates that fluid redistribution of PGE is minimal with only Pd, Au, and Cu being partially remobilized and decoupled from BMS. This is also indicated by the lower concentrations of Pd evident in both pyrite and millerite compared with the pentlandite being replaced. The observations that the GNPA member was mineralized prior to intrusion of the Main Zone and that there was no local footwall control over the development of sulfide mineralization are inconsistent with genetic models involving the in situ development of a sulfide liquid through either depletion of an overlying magma column or in situ contamination of crustal S. We therefore believe that our observations are more compatible with a multistage emplacement model, where preformed PGE-rich sulfides were emplaced into the GNPA member. Such a model explains the development and distribution of a single sulfide liquid throughout the entire 400-800 m thick succession. It is therefore envisaged that the GNPA member formed in a similar manner to its nearest analogue the Platreef. Notable differences however in PGE teno...

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Section: Hydrothermal Interactionsupporting

confidence: 66%

Precious and base metal geochemistry and mineralogy of the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex, South Africa: implications for a multistage emplacement

2014

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“…Pt-Te-Bi inclusions found during laser ablation of some sulfide blebs in MM101 reflect the preferential complexation of Pd and Pt with melts enriched in Te, Bi or As which crystallised PGM microphases during cooling (Helmy et al, 2007;Holwell and McDonald, 2010). Such an interpretation has already been proposed for the origin of Pt\Pd\Te\Bi microphases associated with pentlandite-chalcopyrite-Bo assemblages in mantle peridotites (Lorand et al, 2008(Lorand et al, , 2010Luguet et al, 2004) and in PGE ores (Gervilla and Kojonen, 2002;Gervilla et al, 1997;Helmy et al, 2007;Holwell and McDonald, 2010). The IPGE and Pd enrichments in some pentlandite Group-I dunites (MM101, Fig.…”

Section: Pge Transfers During Interaction Between Volatile-rich Meltsmentioning

confidence: 61%

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

Delpech

Lorand

Grégoire

et al. 2012

Lithos

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“…The Kevitsa mineralised ultramafic intrusion has been the subject of many studies which provide good constraints on its geometry, internal compositional variations in base metals and PGE, intensity and distribution of the various hydrothermal alteration styles, and on the main structures possibly affecting the system (Gervilla and Kojonen, 2002;Grinenko et al, 2003;Hanski et al, 2001;Mutanen, 1997;Mutanen and Huhma, 2001;Standing et al, 2009;Yang et al, 2013;Santaguida et al, 2015). The Kevitsa deposit shows a wide range of primary metal tenors, in texturally homogeneous disseminated ores, with rock types ranging from essentially fresh igneous pyroxenites and peridotites to extensively hydrated amphibolites showing a range of different alteration assemblages (Mutanen, 1997).…”

Section: Introductionmentioning

confidence: 99%

Effects of hydrous alteration on the distribution of base metals and platinum group elements within the Kevitsa magmatic nickel sulphide deposit

Vaillant

Barnes

Fiorentini

et al. 2016

Ore Geology Reviews

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THE PLATINUM-GROUP MINERALS IN THE UPPER SECTION OF THE KEIVITSANSARVI Ni Cu PGE DEPOSIT, NORTHERN FINLAND

Cited by 69 publications

References 34 publications

Precious and base metal geochemistry and mineralogy of the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex, South Africa: implications for a multistage emplacement

Precious and base metal geochemistry and mineralogy of the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex, South Africa: implications for a multistage emplacement

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

Effects of hydrous alteration on the distribution of base metals and platinum group elements within the Kevitsa magmatic nickel sulphide deposit

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