Metamorphic Conditions and Raman Spectroscopic Carbonaceous Material Thermometry of Host Schists of Olympiada and Eldorado Gold Deposits (Yenisey Ridge, Russia)

Abstract

Metamorphic processes play a key role in forming orogenic gold deposits. In this paper, we present new evidence that host schists of the two largest gold deposits of the Yenisey ridge (Russia) Olympiada and Eldorado underwent a single stage of metamorphism in contrast to surrounding blocks. This metamorphism is of moderate thermal gradient and belongs to the Barrovian type, which is typical for the collisional event in the time range 800–850 Ma. The new Ar/Ar age data presented in this paper and the review of magmatic and metamorphic events and ore-forming processes indicate that the most productive stage (gold-sulfide-quartz) correlates well in time with the regional metamorphism of the Barrovian type. This indicates that metamorphic processes can have a crucial role in forming gold deposits of the Yenisey ridge. Carbonaceous material thermometry indicates a wide range of obtained temperatures around 90–150 °C around the mean temperature for each sample. The highest temperatures are close to the peak metamorphic temperatures estimated by garnet-biotite thermometry.