First occurrence of platinum group minerals in ultramafites of the Kizir-Burluksky massif (Western Sayan Mountains, Russia)

Yurichev А. N., Chernyshov A. I., Korbovyak E. V.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2021. V. 150. N 4. P. 77-91

https://doi.org/10.31857/S0869605521040092

Language: Russian

Abstract

For the first time, micron-sized platinum group minerals (PGM) have been revealed in dunites and apodunite serpentinites of the Kyzyr-Burluksky ultramafic massif, occurring in the Kurtushibinsky ophiolite belt. Two groups of PGM have been characterized: Os–Ir–Ru and Pt–Pd, with significant predominance of the latter. The leading role of osmium in the composition of metallic solid solutions indicates a significant role of osmium at early stages of the process of ore formation and its mobilization from parent lherzolites. The later sulfides of rare platinum group elements (Ru, Os, Ir) with minor Cu, Ni и Fe, which compositions correspond to MeS, Me₄S₃, and Me₃S₂ were found. It is noted that Pd, together with Hg, are characteristic elements in the ore-forming system of late platinoids with Pt–Pd specialization. The process of the MPG formation included several stages. The earliest assemblage consists of Os–Ir–Ru solid solutions as well as phases Pt3(Cu,Ni) and (Pt,Os,Re)₃(Ni,Fe,Cu). The rest of PGMs belongs to later assemblages and associates with processes of the mantle-crustal metasomatism, when, under influence of reduced fluids enriched in Hg and S and bearing such elements as Co, Cu, Pd, Au, Ag, Cd, processes of remobilization and redeposition of PGE took place.

Keywords: restitic ultramafites, ophiolites, platinum group minerals (PGM), Western Sayan Mountains, Kizir-Burluksky massif