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GOLD COMPOSITION AND PTX FORMATION CONDITIONS OF THE TARDAN-2 GOLD-SULPHIDE-QUARTZ ORE MANIFESTATION IN BERESITES (EASTERN TUVA)

R. V. Kuzhuget 1, N. N. Ankusheva 2,3, A. A. Redina 4, I. R. Prokopyev 4,5, Yu. V. Butanayev 1, Kh. Kh. Ondar 6

1 Tuva Institute for the Integrated Development of Natural Resources SB RAS, Kyzyl, Russia; 2 Institute of Mineralogy, SU FSC MG UB RAS, Miass, Russia; 3 South Ural State University, Miass Branch, Miass, Russia, 4 V.V.Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, Russia; 5 Novosibirsk State University, Novosibirsk, Russia; 6 United Geological Company LLC, Moscow, Russia

We considered the mineralogical and geochemical peculiarities of native gold, the conditions of ore formation and genesis of Tardan-2 gold occurrence situated in berezitized plagiogranites and granodiorites. We identified that Tardan-2 belongs to low-sulfide gold-quartz beresite-listwänite formation type with the wide variations in the gold fineness from 834 to 201 ‰ (607 ‰, in average) and evolution of native gold composition from medium-fineness gold to mercury kustelite. According to the composition of the Au-bearing assemblages, the Tardan-2 corresponds to the gold-bismuth-sulfosalt-chalcopyrite mineral type with Bi mineralization and minerals of the Au-Ag-Hg series. We determined that the Au-bearing assemblages was formed in the hypabyssal facies environment (depth 2,1–3,0 km; P 0,73–0,98 kbar) due to Na, K and Mg chloride fluids with salinity of 8,7–1,7 wt. % NaCl equiv. and temperatures of 280–120 °C.

Keywords: native gold, Au–Ag–Hg minerals, gold fields, Tuva, fluid inclusions, formation conditions.

DOI 10.20403/2078-0575-2019-4-89-104