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Compounds of Ru-Se-S, alloys of Os-Ir, framboidal Ru nanophases, and laurite-clinochlore intergrowths in the Pados-Tundra Complex, Kola Peninsula, Russia

Andrei Y. Barkov, Andrey A. Nikiforov, Nadezhda D. Tolstykh, Gennadiy I. Shvedov and Vladimir N. Korolyuk
Compounds of Ru-Se-S, alloys of Os-Ir, framboidal Ru nanophases, and laurite-clinochlore intergrowths in the Pados-Tundra Complex, Kola Peninsula, Russia
European Journal of Mineralogy (June 2017) 29 (4): 613-621

Abstract

This is the first report of occurrences of platinum-group minerals (PGM) and unnamed phases of platinum-group elements (PGE) from the Pados-Tundra ultramafic complex of Paleoproterozoic age, Kola Peninsula. The PGM occur as individual inclusions or intergrowths (< or =1-10 mu m) hosted by cores of zoned grains of chromite-magnesiochromite (Chr) in chromitite of the Dunite block in the eastern portion of the complex. Osmium-poor laurite is abundant, commonly as intimate intergrowths with clinochlore (>80% laurite grains), followed by Os- and Ir-dominant alloys (i.e., the minerals osmium and iridium, respectively); unnamed phases of ruthenium selenide [RuSe (sub 2) ] and rhodium telluride [RhTe] are rare. Selenium-rich laurite, not reported previously, likely belongs to an inferred RuS (sub 2) -RuSe (sub 2) series. Native Ru forms micro-(nano)-spherules in framboid-type aggregates, in association with relict laurite, which are surrounded by a skeletal grain of clinochlore; the host is Chr. The framboidal texture of nanophases of ruthenium, hitherto unreported in PGE alloys, likely formed as a result of deposition from a H (sub 2) -bearing fluid, involving a reaction of desulfurisation and reduction of laurite. A highly S-deficient environment is indicated; a low sulfur fugacity, presumably below the Os-OsS (sub 2) buffer, caused the observed coexistence of a low-Os variety of laurite with Os-dominant alloy. An ultimate loss of total S is implied to have decreased the S/Se ratio, which resulted in the precipitation of Ru-dominant sulfoselenide-selenide phases, likely from an oxidizing fluid at a late stage of mineralization. We also infer that the laurite-clinochlore intergrowths crystallized relatively late, from microvolumes of an H (sub 2) O-bearing fluid of contrasting composition, enriched in Ru, S, and lithophile elements.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 29
Serial Issue: 4
Title: Compounds of Ru-Se-S, alloys of Os-Ir, framboidal Ru nanophases, and laurite-clinochlore intergrowths in the Pados-Tundra Complex, Kola Peninsula, Russia
Affiliation: Cherepovets State University, Research Laboratory of Industrial and Ore Mineralogy, Novosibirsk, Russian Federation
Pages: 613-621
Published: 20170628
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 41
Accession Number: 2017-082605
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables, geol. sketch map
N66°00'00" - N70°00'00", E32°00'00" - E42°00'00"
Secondary Affiliation: Russian Academy of Science, Siberian Branch, V. S. Sobolev Institute of Geology and Mineralogy, RUS, Russian FederationSiberian Federal University, RUS, Russian Federation
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201743
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