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The composition and mode of formation of the Pechenga nickel deposits, Kola Peninsula, northwestern Russia

Barnes Sarah-Jane, Melezhik Victor A. et Sokolov Stanislav V.. (2001). The composition and mode of formation of the Pechenga nickel deposits, Kola Peninsula, northwestern Russia. The Canadian Mineralogist, 39, (2), p. 447-471.

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The Pechenga Ni-sulfide deposits, in the Kola Peninsula of Russia, are associated with ferropicrite flows and intrusions. The sulfides are divided into five types: 1) disseminated sulfides within the olivine cumulate portions of the ferropicrites, 2) massive sulfides, which occur at the contact between the ferropicrites and the country-rock black schists, 3) breccia-matrix sulfides, which occur at the contact between the ferropicrites and the schists, and in some cases continue for hundreds of meters subparallel to the contact but within the footwall, 4) chalcopyrite vein or stringer sulfides, which occur in the footwall, and 5) pyrite-rich layers, concretions and lenses in the sedimentary rocks. The disseminated sulfides have similarly shaped mantle-normalized patterns of chalcophile metal abundances to those of the ferropicrites, and could have formed in equilibrium with the ferropicritic magma at moderate R factors (250). The rocks are depleted in platinum-group elements (PGE), suggesting that the magma reached sulfide saturation prior to the formation of the ores. Sulfur isotope data indicate that the S was derived from the sediments onto and into which the ferropicrites were emplaced. The high As and Sb concentrations in the sulfides may have been derived from the sediments. The massive sulfides show a wider variety of composition than the disseminated sulfides; some sulfides are enriched in Os, Ir, Ru, Rh and depleted Pt, Pd, Ag, Au, Cu, Sb, As, Se. This pattern is attributed to the accumulation of monosulfide solidsolution during crystallization of a sulfide liquid. The sedimentary sulfides are richer in As and Sb than the disseminated and massive sulfides, but poorer in all the other chalcophile elements. The breccia-matrix sulfides consist of sedimentary and ultramafic fragments in a sulfide matrix. Compared with vein sulfides from other deposits, those from Pechenga have a very unusual composition. They are not only rich in Cu and Ag, but also in Os, Ir, Ru and Rh, and they are depleted in Pt, Pd, Au, As, Sb and Se.

Type de document:Article publié dans une revue avec comité d'évaluation
Volume:39
Numéro:2
Pages:p. 447-471
Version évaluée par les pairs:Oui
Date:2001
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:nickel sulfide deposits, platinum-group elements, arsenic, antimony, gold, selenium, silver, rare-earth elements, ferropicrites, sulfur isotopes, Pechenga, Russia
Déposé le:10 juin 2016 14:04
Dernière modification:09 déc. 2016 14:51
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