Pogranichnoe Au-Bi occurrence, Eastern Sayan: Composition and link to magmatism

The Pogranichnoe ore occurrence of gold-bismuth type is closely related to Ordovician granitic rocks pertaining to the Sarkhoi granodiorite-granite complex of calc-alkaline series. This type of mineralization in the Eastern Sayan is described for the first time. The orebodies are represented by quartz veins and veinlets with greisenized granite as selvages. Three mineral assemblages consecutively follow one another: (1) pyrite-arsenopyrite, (2) base-metal with fahlore and Sb sulfosalts, and (3) gold-bismuth. The geological position of orebodies and character of microinclusions in accessory minerals of granites suggest that goldbismuth mineralization is related to granitoids.