Sources of Cu-rich Sulfide Mineralization and High-Ni Olivine of the Rudnaya Dike (Imangda Cluster, Norilsk region): Based on Compositional, Isotope and Model Data

Brovchenkoa, V.D.; Kirilinnaa, I.A.; Yudovskayaa, M.A.; Costinc, G.; Pshenitsynd, I.V.; Kovalchuka, E.V.; Larionovaa, Y.O.; Gritsenkod, Y.D.; Ketrove, A.A.

Авторы: Brovchenkoa V.D., Kirilinnaa I.A., Yudovskayaa M.A., Costinc G., Pshenitsynd I.V., Kovalchuka E.V., Larionovaa Yu O., Gritsenkod Yu D., Ketrove A.A.
Журнал: Petrology
Том: 31
Номер: 6
Год издания: 2023
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 1
Последняя страница: 26
DOI: 10.31857/S0869590323060067
Аннотация: The Rudnaya dike of the Imangda ore cluster is composed of the weakly differentiated olivine-bearing to olivine gabbrodolerites with sulfide globules and disseminated sulfides of (pentlandite-pyrrhotite)–chalcopyrite–cubanite composition. Along with cogenetic sulfide mineralization, dike gabbrodolerites contain xenoliths of hornfelsed basalts, abundant amygdales and rare grains of zoned Ol-1 Fo90-47 that coexists with subhedral olivine Fo75-36 of the second generation. Modeling using the COMAGMAT and alphaMELTS programs showed that high-Mg Ol-1 with Cr-spinel inclusions could not be crystallized from a Fe-enriched tholeiitic magma that is parental for the dike with 4.8–7.3 wt. % MgO and 11.6–16.7 wt. % total Fe2O3. The variation trend and high Ni up to 0.5 wt. % in the cores of xenocrystic olivine Fo90-76 in contrast to maximum Fo83 and 0.4 wt. % NiO in olivine from the ore-bearing intrusions and picritic basalts of the Norilsk region point toward the presence of picritic cumulates, which magma had not exchanged with sulfide liquid.Platinum group element (PGE) abundances increase (up to 2.2 ppm) with Cu/Ni in the whole rocks as well as with proportions of pentlandite in a sulfide association. The Ni, Os and Ir minima in chalcophile metal distribution, elevated Cu/Ni (5–15) and Cu/Pd (3200–10900) ratios as well as lower PGE tenor of sulfides (2–65 ppm) and Pd content in pentlandite (<175 ppm) compared to those of ore-bearing intrusions suggest that Cu-rich sulfide mineralization was not mechanically captured from highly fractionated sulfide fractions of ore-bearing magmas but is cogenetic with a magma of the dike. Sulfide saturation near-simultaneous with fluid saturation and degassing was achieved in the dike conduit due to assimilation of sedimentary sulfur and volatiles from Devonian evaporites, which is supported by the heavy S isotope composition of dike sulfides with the average δ34S = 14.7 ±1.1‰ (n = 31) close to the values in sulfides from the endocontact zones of the ore-bearing Imangda intrusions hosted by Devonian sequences. The initial isotopic characteristics of dike rocks (Sri 0.70517–0.70532, ɛNd from –0.4 to 0.8) imply its comagmatic origin with the Norilsk-type intrusions whereas the overall data do not exclude even its spatial connection with an upper crustal conduit system of the ore-bearing magmas.
Добавил в систему: Гриценко Юлия Дмитриевна

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Sources of Cu-rich Sulfide Mineralization and High-Ni Olivine of the Rudnaya Dike (Imangda Cluster, Norilsk region): Based on Compositional, Isotope and Model Dataстатья

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