Тип публикации: статья из журнала
Год издания: 2017
Идентификатор DOI: 10.1127/ejm/2017/0029-2666
Ключевые слова: platinum-group elements, platinum-group minerals, ruthenium, alloy minerals, RuS2-RuSe2 compounds, framboidal textures, chromitite, chromite-magnesiochromite, Pados-Tundra, Kola Peninsula, Russia
Аннотация: 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 ( 80% laurite grains), followed by Os-and Ir-dominant alloys (i.e., theПоказать полностьюminerals osmium and iridium, respectively); unnamed phases of ruthenium selenide [RuSe2] and rhodium telluride [RhTe] are rare. Selenium-rich laurite, not reported previously, likely belongs to an inferred RuS2-RuSe2 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-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-OsS2 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 H2O-bearing fluid of contrasting composition, enriched in Ru, S, and lithophile elements.
Журнал: EUROPEAN JOURNAL OF MINERALOGY
Выпуск журнала: Vol. 29, Is. 4
Номера страниц: 613-621
ISSN журнала: 09351221
Место издания: STUTTGART
Издатель: E SCHWEIZERBARTSCHE VERLAGSBUCHHANDLUNG