R. V. Kuzhuget, N. N. Ankusheva, A. K. Khertek, A. O. Mongush, Yu. V. Butanaeva
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引用次数: 0
Abstract
Ore mineralization of the Ak-Sug Porphyry Copper–Gold–Molybdenum deposit formed during three stages: 1) porphyry-copper mineralization with simple sulfides in quartz–sericite and quartz–sericite–chlorite metasomatites, 2) subepithermal Au–Bi–Te–Pd-quartz mineralization in quartz–sericite metasomatites, and 3) intermediate-sulfidation Au–Ag mineral assemblages with selenides, tellurides, and Sb and As sulfosalts in argillisites. Fluid inclusion studies (microthermometry, Raman spectroscopy) of quartz and mineral thermometry (an assemblage of Au and Ag tellurides) showed that porphyry copper and subepithermal mineralization precipitated from hydrocarbon–aqueous–chloride (Na–K ± Fe) fluid with salinity of 20.1–32.8 wt % NaCl eq. at 435–375°C and hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 7.5–15.0 wt % NaCl eq. at 415–325°C, respectively. The epithermal mineral assemblages precipitated at ∼0.55 kbar from hydrocarbon–aqueous–chloride (Na–K ± Fe ± Ca ± Mg) fluid with salinity of 1.4–12.6 wt % NaCl eq. at 370–200°C. The latest low-temperature (240–190°С) and diluted (3.5–4.9 wt %) fluids are characterized by variations in Na and K chlorides; Fe2+, Fe3+, Ca, and Mg carbonates; and Na, K, and Mg sulfates. The S isotopic composition of the fluid of different mineral assemblages varies from –2.7 to +0.3‰ and suggest that they are derivatives of a single porphyry system. The δ18О values of the fluid of porphyry copper (7.4‰) and subepithermal (7.0‰) stages indicate its magmatic genesis, whereas those of the epithermal stage (from +1.2 to +7.2‰) are evident of mixing of magmatic fluid and meteoric waters (from +0.4 to +5.7‰). Our isotopic data, combined with mineralogical–geochemical peculiarities and formation conditions of ores, provide tracing the principles of the evolution of mineral assemblages, temperatures, composition, and fluid salinity at the Ak-Sug deposit upon the transition from porphyry copper to epithermal stage.
期刊介绍：
Geology of Ore Deposits is a periodical covering the topic of metallic and nonmetallic mineral deposits, their formation conditions, and spatial and temporal distribution. The journal publishes original scientific articles and reviews on a wide range of problems in theoretical and applied geology. The journal focuses on the following problems: deep geological structure and geodynamic environment of ore formation; distribution pattern of metallogenic zones and mineral deposits; geology and formation environment of large and unique metallic and nonmetallic deposits; mineralogy of metallic and nonmetallic deposits; physicochemical and isotopic characteristics and geochemical environment of ore deposition; evolution of ore-forming systems; radiogeology and radioecology, economic problems in exploring, developing, and mining of ore commodities.
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