Hydrocarbons in Fluid Inclusions from Native Gold, Pyrite, and Quartz of the Sovetskoe Deposit (Yenisei Ridge, Russia) According to Pyrolysis-Free Gas Chromatography-Mass Spectrometry Data

Abstract

––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.

Ore–Bearing Fluids of the Blagodatnoye Gold Deposit (Yenisei Ridge, Russia): Results of Fluid Inclusion and Isotopic Analyses

“…The main argument supporting the conclusions gold was transported by reduced carbon dioxide-hydrocarbon fluid is the composition of fluid extracted from fluid inclusions in native gold from the Sovetskoe deposit. GC-MS analysis showed that the proportion of hydrocarbons in total with S-N-Cl-F-Si-compounds in the composition of gold-bearing fluid reaches 52.0 rel.% [21].…”

“…Elevated contents of N 2 (to 53.5 mol.%) were determined in the gas phase of individual inclusions in quartz, using Raman spectroscopy (Table 2). Molecular nitrogen and nitrogenated compounds are constantly present in the gas phase of fluid inclusions in native gold [21]. Nitrogenated, the same as sulfonated and halogenated compounds, may take part in complex formation and transport of gold [47][48][49][50].…”

“…The purity of helium was 99.9999%. The procedure of GC-MS analysis was described in [21,32,33]. When preparing the samples for analysis, we did not use acids, solvents or organic substances which could distort the initial (parental) composition of the extracted fluid.…”

“…The ore field of the deposit is located in the Severo-Yeniseisky district of the Yenisei Ridge on the southeast wing the Panimba anticlinorium bounded by the Tatarka deep fault in the west and Ishimba deep fault in the east (Figure 1a). ridge [18][19][20][21]. The aim of our work is to reveal the physicochemical properties of orebearing fluids that formed the Blagodatnoye deposit in the Yenisei Ridge, which ranks the second in gold reserves.…”

“…Recently we developed a special device that is used for gas mixture injection upon shock destruction of a sample, which in combination with a highly sensitive gas chroma tography-mass spectrometer allowed obtaining original results on the composition of gas component of fluids in native gold, quartz and sulfides from gold deposits of the Yenisei ridge [18][19][20][21]. The aim of our work is to reveal the physicochemical properties of ore-bearing fluids that formed the Blagodatnoye deposit in the Yenisei Ridge, which ranks the second in gold reserves.…”