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Russian Geology and Geophysics

2011 year, number 3

PHYSICOCHEMICAL MODELING OF MINERAL FORMATION PROCESSES AT THE BADRAN GOLD DEPOSIT ( Yakutia )

A.A. Obolenskya, L.V. Gushchinaa, G.S. Anisimovab, E.S. Serkebaevab, A.A. Tomilenkoa, and N.A. Gibshera
a V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
b Institute of Diamond and Noble-Metal Geology, Siberian Branch of the Russian Academy of Sciences, pr. Lenina 39, Yakutsk, 677980, Russia
Keywords: Gold deposit, fluid inclusion, composition of hydrothermal solution, thermodynamic model
Pages: 290-306

Abstract

The physicochemical modeling of mineral formation processes at the Badran subthrust gold-quartz deposit was performed, based on a study of fluid inclusions in quartz by Raman spectroscopy, gas chromatography, thermometry, and freezing. The results show that at stage I, highly productive gold-bearing quartz veins (gray quartz) of the deposit formed from heterogeneous fluid at <320 ?C and 2.0-0.1 kbar with the active participation of CO2, N2, and CH4; the salinity of this solution reached 10 wt.% NaCl-equiv. At stage II (Au-productive), milky-white quartz was produced from the homogeneous medium-chloride-sulfide solution which remained after the heterogenization of the initial fluid, at 300-100 ?C and 0.1 kbar. At stage III (with low Au production), clear quartz formed from homogeneous chloride solutions with salinity of <4.5 wt.% NaCl-equiv. at <200 ?C and <0.1 kbar.
The physicochemical conditions of Au concentration within the complex geochemical system Au-Fe-Cu-Pb-Zn-As-Sb-Hg-Ag-H2O-Cl-H2S-CO2 at the Badran deposit was modeled using the Chiller software. The following models were used: (1) solution-rock interaction and (2) condensation of gas phase (for stage I); (3) simple cooling of medium-chloride-sulfide solution (for stage II); (4) simple cooling and (5) mixing of low-chloride-sulfide solution with acid meteoric waters (for stage III). The models show the sequence of vein formation in the ore-producing system and the host-rock metasomatism in the deep horizons of the deposit.