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Basalt alteration in high-temperature oxidizing-type fumaroles at the Tolbachik volcano (Kamchatka, Russia). Part 1: Processes and products of olivine alterationстатья
- Авторы: Bulakh M.O., Pekov I.V., Koshlyakova N.N., Nazarova M.A.
- Журнал: Geology of Ore Deposits
- Том: 66
- Номер: 8
- Год издания: 2024
- Издательство: Maik Nauka/Interperiodica Publishing
- Местоположение издательства: Russian Federation
- Первая страница: 1057
- Последняя страница: 1082
- DOI: 10.1134/S1075701524700235
- Аннотация: This paper is devoted to the olivine pseudomorphization processes occurring in basalt under theaction of high-temperature O2-rich gas in oxidizing-type fumaroles at the Tolbachik volcano (Kamchatka,Russia). The alteration of olivine Fo72–90 in a terraneous oxidizing-type exhalation system involves two independent processes: (1) oxidative breakdown (above 600°C) with the formation of forsterite Fo90–100 togetherwith hematite, magnesioferrite, and, presumably, “magnesian laihunite” and (2) replacement by mineralaggregates in which pyroxenes [enstatite, clinoenstatite, diopside, aegirine–augite(Ca0.5Na0.5)(Mg0.5Fe0.5)Si2O6], low-alumina fluoromagnesian micas (yangzhumingite and fluorotetraferriphlogopite), chondrodite, or cristobalite are the main components accompanied by hematite, sometimeswith magnesioferrite or tenorite. In the active Arsenatnaya fumarole, the change of the main Si minerals inpseudomorphs with the gas temperature decrease occurs in a sequence that generally reflects an increase inthe degree of condensation of tetrahedral Si–O motifs: olivine (forsterite) → orthopyroxene (enstatite) →clinopyroxenes → micas → cristobalite.
- Добавил в систему: Булах Мария Олеговна