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Russian Geology and Geophysics

2015 year, number 3

THE BEHAVIOR OF ORE ELEMENTS IN OXIDIZED HETEROPHASE CHLORIDE AND CARBONATECHLORIDESULFATE FLUIDS OF PORPHYRY CuMo(Au) DEPOSITS (from experimental data)

A.A. Borovikov1, T.A. Bulbak1, A.S. Borisenko1,2, A.L. Ragozin1, S.V. Palesskii1
1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Synthetic fluid inclusions, ore deposits, ore formation

Abstract

The spatial coexistence and synchronous formation of magmatogene porphyry Cu-Mo mineralization and epithermal gold mineralization are due to the genetic relationship between their formation processes. This relationship might be due to the generation of metal-bearing fluids of different geochemical compositions by the porphyry ore-magmatic system, which then participate in the formation of magmatogene porphyry Cu-Mo(Au) and associated epithermal gold deposits. Synthesis of fluid inclusions in quartz was performed for experimental study of the behavior of Cu, Mo, W, Sn, Au, As, Sb, Te, Ag, and Bi in heterophase fluids similar in composition and aggregate state to natural ore-forming fluids of porphyry Cu-Mo(Au) deposits. We have established that at 700 ºC, a pressure decrease from 117 to 106 MPa leads to a significant enrichment of the gas phase of heterophase chloride fluid with Au, As, Sb, and Bi. The heterophase state of carbonate-chloride-sulfate fluids is observed at 600 ºC and 100-90 MPa. It characterizes the highly concentrated liquid carbonate-sulfide phase-liquid chloride phase-low-density gas phase equilibrium. A decrease in the pressure of heterophase carbonate-chloride-sulfate fluid leads to a noticeable enrichment of its chloride phase with Cu, Mo, Fe, W, Ag, Sn, Sb, and Zn relative to the carbonate-sulfate phase. The processes of redistribution of ore elements between the phases of heterophase fluids can be considered a model of generation of metal-bearing chloride fluids, which occurs in nature during the formation of porphyry Cu-Mo(Au) deposits, as well as a model of generation of gas fluids supplying Au, Te, As, and other ore elements to the place of formation of epithermal Au-Cu and Au-Ag mineralization.

DOI: http://dx.doi.org/10.1016/j.rgg.2015.02.005