P-T-X parameters of metamorphogene and hydrothermal fluids, isotopy and age of the Bogunai gold deposit, southern Yenisei Ridge (Russia)

• Published in: Russian geology and geophysics Vol. 56; no. 6; pp. 903 - 918
• Main Authors: Ryabukha, M.A., Gibsher, N.A., Tomilenko, A.A., Bul’bak, T.A., Khomenko, M.O., Sazonov, A.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2015; Allerton Press
• Subjects: absolute age; alcohols; aliphatic hydrocarbons; alkanes; Angara-Kan Block; Ar-40/Ar-39; Ar-Ar age; Ar/Ar; argon; aromatic hydrocarbons; Asia; Bogunay Deposit; chromatograms; Commonwealth of Independent States; dates; Economic geology; fluid inclusions; fluid phase; galena; garnet group; gas chromatograms; geologic thermometry; gold; gold ores; granites; homogenization; hydrocarbons; hydrothermal conditions; igneous rocks; inclusions; isotope ratios; isotopes; Krasnoyarsk Russian Federation; Lower Kan Pluton; mass spectra; metal ores; microthermometry; mineral deposits, genesis; naphthalene; nesosilicates; noble gases; Ordovician; ore-forming fluid; organic compounds; orthosilicates; P-T conditions; Paleozoic; paraffins; Permian; plutonic rocks; polycyclic aromatic hydrocarbons; quartz; quartz veins; radioactive isotopes; Raman spectra; Russian Federation; S-34/S-32; S34S; Siberia; Siberian Platform; silicates; spectra; stable isotopes; sulfides; sulfur; Upper Permian; veins; Yenisei Ridge; gold; hydrocarbons; quartz; S34S; ore-forming fluid; Ar-Ar age; sulfides
• ISSN: 1068-7971; 1878-030X
• DOI: 10.1016/j.rgg.2015.05.007

Fluid inclusions in quartz, sulfides from quartz veins, and quartz, garnet, plagioclase, and orthoclase from granulites of the Bogunai gold deposit located in the granulites of the Angara-Kan block of the Yenisei Ridge were studied by thermobarometry, gas chromatography, chromato-mass-spectrometry, Raman spectroscopy, and mass spectrometry with inductively coupled plasma. The formation temperatures (850-950 °C) and pressures (8.5-9.0 kbar) of minerals of the granulite metamorphic facies are much higher than the crystallization temperatures (220-420 °C) and pressures (0.1-1.6 kbar) of gold-quartz veins of the Bogunai deposit. These veins formed with the participation of H2O-CO2-hydrocarbon fluids with a salt (predominantly MgCl2) concentration of 2-19 wt.% NaCl equiv. The gas phase of fluid inclusions from quartz, pyrite, chalcopyrite, galena, and sphalerite contains not only H2O, CO2, CH4, and N2 but also the first found compounds of sulfur (CS2, O2S, COS, C2H6S2) and nitrogen (C3H7N, C3H7NO, C4H8N2O) and numerous hydrocarbons of different classes (paraffins, arenes, naphthenes, alcohols, aldehydes, ketones, carbonic acids, and furans). The age of the Krasnoyarsk mineralized zone, one of the sites of the Bogunai deposit, is 466 ± 3.2-461.6 ± 3.1 Ma, which is almost 1400 Ma younger than the age of granulite metamorphism and 255 Ma younger than the age of diaphthoresis but is close to the age of the Lower Kan granitoid pluton (455.7 ± 3.4 Ma). The sulfur isotope ratios (534S) of sulfides (pyrite, chalcopyrite, sphalerite, and galena) are close to the mantle values, 0.8 to 3.5%c, and are in the range of the granitoid values, which indicates the crustal source of the fluid sulfur. Gold of the Bogunai deposit accumulated with the participation of H2O-CO2-hydrocarbon fluids generated both in deep-fault zones and in granitoid intrusions.