––The first results on the composition of fluids from native gold and associated pyrite and quartz have been obtained. Despite the small amount of analytical data, these results are of scientific and practical interest. The identified geochemical criteria can be used for the assessment of gold ore shoots and the substantiation of prospecting in the region. The one-act shock-destructive extraction of volatiles from fluid inclusions and their pyrolysis-free gas chromatography–mass spectrometry analysis made it possible to determine the composition of fluids in native gold and in associated pyrite and quartz. Based on these data, we have first shown that fluids in native gold, pyrite, and quartz are a mineral-forming multicomponent system. In addition to water and carbon dioxide, the studied fluid inclusions contain representatives of at least 11 homologous series of organic compounds, including oxygen-free aliphatic and cyclic hydrocarbons (paraffins, olefins, cyclic alkanes and alkenes, arenes, and polycyclic aromatic hydrocarbons), oxygenated hydrocarbons (alcohols, esters, furans, aldehydes, ketones, and carboxylic acids), and nitrogened, sulfonated, halogenated, and siliconorganic compounds. The portion of hydrocarbons together with S–N–Cl–F–Si compounds reaches 52.0 rel.% in fluid inclusions from native gold, 10.1 rel.% in fluid inclusions from pyrite, and 18.0 rel.% in fluid inclusions from quartz. Gold-transporting gas fluids have reducing properties. Pyrite and quartz contain oxidized water–carbon dioxide fluids with low contents of hydrocarbons and nitrogen–halogenated compounds.

The Blagodatnoye deposit with 340 t gold reserves is one of the most productive mines in Russia. Modern methods of studying fluid inclusions were used to determine the properties of fluids that formed this deposit. A comprehensive study revealed that the Blagodatnoye gold deposit was formed between 120 and 350 °C and at 0.2–2.6 kbar, and from fluids with salinities ranging from 0.5 to 30 wt.% (NaCl–eq.). These fluids are: 1—water–carbon dioxide; 2—carbon dioxide–hydrocarbon; 3—highly saline aqueous. According to Raman spectroscopy and gas chromatography–mass spectrometry, ore–forming fluids contained H₂O, CO₂, hydrocarbons and oxygenated organic compounds, sulfonated, nitrogenated and halogenated compounds. Early oxidized water–carbon dioxide fluids formed barren associations of the deposit. Later reduced carbon dioxide–hydrocarbon fluids had a key role in the formation of gold-bearing quartz veins. The stable isotope data (δ³⁴S = 0.8 to 21.3‰, δ¹³C = −2.8 to −20.9‰, ³He/⁴He = 0.14 ± 0.3 × 10^–6) suggest the ore-forming fluids have a crustal source.

Gold-silver mineralization in the Rodnikovoe LS epithermal deposit is characterized by selenium speciation. Two main alternating ore assemblages have been identified: silver-aguilarite-acanthite and gold-uytenbogaardtite-acanthite. The former mineral association is intergrown with secondary silver (Ag_0.77–0.91), whereas the latter assemblage is closely associated with high-grade gold (Au_0.63–0.67). However, both are dominated by Ag_0.49–0.56Au_0.44–0.51 alloys. The geochemical evolution of the ore-forming system developed in the direction: Fe → Cu; Ag → Au; S → Se; As → Sb. Organic compounds (1 relative %) of both biogenic and thermogenic origin were found in fluid inclusions. These molecules participated in the formation of Ag,Au-complexes and transported noble metals along with selenium. Hydrothermal fluids are characterized by fSe₂/fS₂ ratios < 1, conditions such that the deposition of selenide minerals is inhibited, except for the naumannite and acanthite series. These conditions allow active entry of selenium into sulfosalts (the selenium substitutes for sulfur).

—New thermobarogeochemical and isotope-geochemical data are presented, which show the intricate and long history of the formation of the unique Olimpiadinskoe gold deposit with predicted gold reserves of >1000 tons on the Yenisei Ridge. Metal-bearing oxidized water–carbon dioxide and reduced carbon dioxide–hydrocarbon fluids participated (at the same time or successively) in the formation of the deposit at 220–470 °C and 0.6–2.5 kbar. Fluids of gold-bearing mineral assemblages include CO2, hydrocarbons, and S-, N-, and halogen-containing compounds capable of transporting ore elements, including gold. Highly mobile carbon dioxide–hydrocarbon fluids were responsible for the appearance of disseminated gold mineralization in large bodies of quartz–carbonate–mica schists serving as geochemical barriers in the Olimpiadinskoe deposit. The deposit formed in the period from 817 to 660 Ma, which fits the time interval from crystallization to cooling (868–721 Ma) of the most proximal multiphase Chirimba granitoid pluton. The hydrothermal activity of the fluids that formed the Olimpiadinskoe deposit lasted at least 100–150 Myr year.

40Ar/39Ar dates on the quartz–micaceous–sulfide, quartz–gold–arsenopyrite–pyrrhotite, and quartz–gold–stibium associations at the superlarge (>1000 t Au) Olimpiada gold deposit, the Yenisei...