Известия Томского политехнического университета: Инжиниринг георесурсов (Jul 2020)

ARYSKAN GOLD-SULPHIDE-QUARTZ ORE OCCURRENCE (WESTERN TUVA): CONDITIONS OF FORMATION AND GEOCHEMICAL PECULIARITIES OF FLUIDS

  • Renat V. Kuzhuget,
  • Natalia N. Ankusheva,
  • Anna A. Redina,
  • Ilya R. Prokopyev,
  • Ertine Dash V. Ondar

DOI
https://doi.org/10.18799/24131830/2020/7/2732
Journal volume & issue
Vol. 331, no. 7
pp. 224 – 237

Abstract

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The relevance of the research defined by the need to determine the genesis and formation conditions of gold deposits from Tuva Republic for improving the efficiency of geological prospecting and increasing the gold mineral resource base of the region. The aim of the research is to examine the conditions of fluid formation and geochemical peculiarities of Aryskan gold ore occurrence in Western Tuva. Analytical methods. The temperatures, fluid composition, salinity, and trapping pressures were examined due to fluid inclusion study by means of Linkam TMS-600 cryostage equipped with Olympus BX 51 optical microscope; gas composition of fluid inclusions was detected using Ramanor U-1000 Raman spectrometer equipped with Horiba DU420E-OE-323 detector and Millennia Pro (Spectra-Physics) laser; bulk element composition of fluid was determined on Agilent 6890 gas chromatograph, extracted anion amounts of fluid were detected used TSVET-3000 ion chromatograph, cations and trace elements – by means of ICP MS (Elan-6100); S isotopic compositions were specified on Finnigan MAT Delta gas mass-spectrometer. Results. We specified that early beresites of Aryskan ore occurrence were formed due to CO2 water-chloride fluid with salinity ranged between 4,9 and 41,5 wt. % NaСl equiv. and temperatures from 250 to 340 °C. The Au-bearing mineral associations were formed at P ~1,8 kbar (~5,4 km depth) in mesoabissal environment due to CO2 watered fluids contained NaCl-KCl-H2O, NaCl-Na2НCO4-H2O и NaCl-H2O with salinity from 2,9 up to 32,9 wt. % NaСl equiv. in front of the temperatures ranged between 290–145 °C (I Au-bearing substage – 290–145 °С, II Au-bearing substage – 270–160 °С) with varying f O2, f S2, f Se2 и f Te2. The isotopic δ34SH2S (from -0,5 up to +1,1 ‰) and salt composition of fluid and trace elements indicate its magmatic genesis.

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