Mineralogy, geochemistry and stratigraphy of the Maslovsky Pt–Cu–Ni sulfide deposit, Noril’sk Region, Russia: implications for relationship of ore-bearing intrusions and lavas

Krivolutskaya, Nadezhda Alexandrovna, Sobolev, Alexandr Vladimirovich, Snisar, Sergey Grigor’evich, Gongalskiy, Bronislav Iosiphovich, Kuzmin, Dmitry Vladimirovich, Hauff, Folkmar, Tushentsova, Irina Nikolaevna, Svirskaya, Natalya Mikhailovna, Kononkova, Natalya Nikolaevna and Schlychkova, Tatyana B. (2012) Mineralogy, geochemistry and stratigraphy of the Maslovsky Pt–Cu–Ni sulfide deposit, Noril’sk Region, Russia: implications for relationship of ore-bearing intrusions and lavas Mineralium Deposita, 47 (1). pp. 69-88. DOI 10.1007/s00126-011-0372-5. Date online first: 2011

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Abstract

We report new data on the stratigraphy, mineralogy and geochemistry of the rocks and ores of the Maslovsky Pt–Cu–Ni sulfide deposit which is thought to be the southwestern extension of the Noril’sk 1 intrusion. Variations in the Ta/Nb ratio of the gabbro-dolerites hosting the sulfide mineralization and the compositions of their pyroxene and olivine indicate that these rocks were produced by two discrete magmatic pulses, which gave rise to the Northern and Southern Maslovsky intrusions that together host the Maslovsky deposit. The Northern intrusion is located inside the Tungusska sandstones and basalt of the Ivakinsky Formation. The Southern intrusion cuts through all of the lower units of the Siberian Trap tufflavas, including the Lower Nadezhdinsky Formation; demonstrating that the ore-bearing intrusions of the Noril’sk Complex post-date that unit. Rocks in both intrusions have low TiO2 and elevated MgO contents (average mean TiO2 <1 and MgO=12 wt.%) that are more primitive than the lavas of the Upper Formations of the Siberian Traps which suggests that the ore-bearing intrusions result from separate magmatic event. Unusually high concentrations of both HREE (Dy+Yb+Er+Lu) and Y (up to 1.2 and 2.1 ppm, respectively) occur in olivines (Fo79.5 and 0.25% NiO) from picritic and taxitic gabbro-dolerites with disseminated sulfide mineralization. Thus accumulation of HREE, Yand Ni in the melts is correlated with the mineral potential of the intrusions. The TiO2 concentration in pyroxene has a strong negative correlation with the Mg# of both host mineral and Mg# of host rock. Sulfides from the Northern Maslovsky intrusion are predominantly chalcopyrite–pyrrhotite–pentlandite with subordinate and minor amounts of cubanite, bornite and millerite and a diverse assemblage of rare precious metal minerals including native metals (Au, Ag and Pd), Sn–Pd–Pt–Bi–Pb compounds and Fe–Pt alloys. Sulfides from the Southern Maslovsky intrusion have δ34S=5–6‰ up to 10.8‰ in two samples whereas the country rock basalt have δ34S=3–4‰, implying there was no in situ assimilation of surrounding rocks by magmas.

Document Type: Article
Keywords: Volcanology; Geochemistry; Noril’sk; Pt–Cu–Ni sulfide ores; Olivine; Pyroxene; Sulfur isotopes; Heavy rare-earth elements
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS Magmatic and Hydrothermal Systems
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.1007/s00126-011-0372-5
ISSN: 0026-4598
Projects: Future Ocean
Date Deposited: 12 Jan 2012 10:34
Last Modified: 20 Mar 2017 13:52
URI: http://eprints.uni-kiel.de/id/eprint/13429

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