Ore-bearing fluids of the Eldorado gold deposit (Yenisei Ridge, Russia)

Тип публикации: статья из журнала

Год издания: 2018

Идентификатор DOI: 10.1016/j.rgg.2018.07.018

Ключевые слова: quartz, gold, ore-forming fluid, hydrocarbons, delta S-34, He-3/He-4, Ar-Ar age, 3He/4He, δ34S

Аннотация: The Eldorado low-sulfide gold-quartz deposit, with gold reserves of more than 60 tons, is located in the damage zone of the Ishimba Fault in the Yenisei Ridge and is hosted by Riphean epidote-amphibolite metamorphic rocks (Sukhoi Pit Group). Orebodies occur in four roughly parallel heavily fractured zones where rocks were subject to metamorphism under stress and heat impacts. They consist of sulfide-bearing schists with veins of gray or milky-white quartz varieties. Gray quartz predominating in gold-bearing orebodies contains graphite and amorphous carbon identified by Raman spectroscopy; the contents of gold and amorphous carbon are in positive correlation. As inferred from thermobarometry, gas chromatography, gas chromatography-mass spectrometry, and Raman spectroscopy of fluid inclusions in sulfides, carbonates, and gray and white quartz, gold mineralization formed under the effect of reduced H2O-CO2-HC fluids with temperatures of 180 to 490 degrees C, salinity of 9 to 22 wt.% NaCl equiv, and pressures of 0.1 to 2.3 kbar. Judging by the presence of 11% mantle helium (He-3) in fluid inclusions from quartz and the sulfur isotope composition (7.1-17.4 parts per thousand delta S-34) of sulfides, ore-bearing fluids ascended from a mantle source along shear zones, where they "boiled". While the fluids were ascending, the metalliferous S-and N-bearing hydrocarbon (HC) compounds they carried broke down to produce crystalline sulfides, gold, and disseminated graphite and amorphous carbon (the latter imparts the gray color to quartz). Barren veins of milky-white quartz formed from oxidized mainly aqueous fluids with a salinity of 30 wt.% NaCl equiv) at 150-260 degrees C impregnated the gold-bearing quartz veins and produced the lower strata of the hydrothermal-granitoid section. The gold mineralization (795-710 Ma) was roughly coeval to local high-temperature stress metamorphism (836-745 Ma) and intrusion of the Kalama multiphase complex (880-752 Ma). (C) 2018, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

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Издание

Журнал: RUSSIAN GEOLOGY AND GEOPHYSICS

Выпуск журнала: Vol. 59, Is. 8

Номера страниц: 983-996

ISSN журнала: 10687971

Место издания: AMSTERDAM

Издатель: ELSEVIER SCIENCE BV

Авторы

  • Gibsher N.A. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Tomilenko A.A. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Sazonov A.M. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Bul'bak T.A. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Khomenko M.O. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Ryabukha M.A. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Shaparenko E.O. (Russian Acad Sci, VS Sobolev Inst Geol & Mineral, Siberian Branch, Pr Akad Koptyuga 3, Novosibirsk 630090, Russia)
  • Sil'yanov S.A. (Siberian Fed Univ, Inst Min Geol & Geotechnol, Pr Svobody 79, Krasnoyarsk 660041, Russia)
  • Nekrasova N.A. (Siberian Fed Univ, Inst Min Geol & Geotechnol, Pr Svobody 79, Krasnoyarsk 660041, Russia)

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