Reduced CO2 Fluid as an Agent of Ore-Forming Processes: A Case Study of Dolomite-Replacement Skarns at the Yoko-Dovyren  Massif

Simakin, A.G.; Kislov, E.V.; Salova, T.P.; Shaposhnikova, O.Y.; Nekrasov, A.N.

Авторы: Simakin A.G., Kislov E.V., Salova T.P., Shaposhnikova O.Yu, Nekrasov A.N.
Журнал: Petrology
Том: 27
Номер: 1
Год издания: 2019
Издательство: Maik Nauka/Interperiodica Publishing
Местоположение издательства: Russian Federation
Первая страница: 4
Последняя страница: 16
Оригинальные версии: ВОССТАНОВЛЕННЫЙ УГЛЕКИСЛЫЙ ФЛЮИД: РОЛЬ В ПЕРЕРАСПРЕДЕЛЕНИИ V, Cr И ЭПГ В КОНТАКТЕ РАССЛОЕННОГО УЛЬТРАБАЗИТ-БАЗИТОВОГО ЙОКО-ДОВЫРЕНСКОГО МАССИВА (СЕВЕРНОЕ ПРИБАЙКАЛЬЕ)
DOI: 10.1134/S086959111901003X
Аннотация: The paper presents newly obtained geochemical data on outer-contact rocks and carbonatereplacement skarns of the Yoko-Dovyren layered ultramafic–mafic intrusion in the northern Baikal area. The rocks initially contained CO2-rich fluid with a high oxygen fugacity (up to NNO + 3–4), which was generated by the partial decomposition of dolomite and by reactions between SiO2 and carbonates. The skarn blue diopside is enriched in Pt (up to 0.2 ppm) and V (300 ppm), and the wollastonite zone of the skarns contains elevated Re concentrations (up to 0.4 ppm). The REE pattern of the contact-zone quartzite is identical to the REE patterns of phlogopite-bearing lherzolites from the lower contact part of the Yoko-Dovyren massif. These geochemical features of the rocks of the intrusion may be explained by the transfer and redeposition of material by reduced H2O–CO2 fluid. According to thermodynamic calculations, a reaction between H2O–CO2 fluid and high-Mg olivine at a subsolidus temperature of T = 950ºC and pressure P = 2 kbar should result in a decrease in the oxygen fugacity to QFM – 2 and, hence, generate much CO. According to the calculations, a low oxygen fugacity (close to QFM + 0.7) can also be maintained by pyrrhotite oxidation with H2O and CO2 fluid components under cumulus P–T parameters. As a result of these reactions, the fluid should enrich in Pt extracted from magmatic sulfides, and this Pt can be redeposited in rocks, including those composing the skarn zones. Keywords: Yoko-Dovyren intrusion, platinum, blue diopside, carbon monoxide, skarn, thermodynamic simulations
Добавил в систему: Шапошникова Ольга Юрьевна

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Reduced CO2 Fluid as an Agent of Ore-Forming Processes: A Case Study of Dolomite-Replacement Skarns at the Yoko-Dovyren Massifстатья Исследовательская статья

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