Fumarolic incrustations at Kudryavy volcano (Kamchatka) as a guideline for high-temperature (>850 °C) extinct hydrothermal systems

• Published in: Journal of Volcanology and Geothermal Research
• Main Authors: Ganino, Clément, Libourel, Guy, Bernard, Alain
• Other Authors: Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (. - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Hawai'i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai'i Honolulu (UH), Université libre de Bruxelles (ULB)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Kamchatka
• Online Access: https://hal.archives-ouvertes.fr/hal-02134579; https://hal.archives-ouvertes.fr/hal-02134579/document; https://hal.archives-ouvertes.fr/hal-02134579/file/S0377027319300058.pdf; https://doi.org/10.1016/j.jvolgeores.2019.03.020

International audience Our knowledge of active magmatic hydrothermal system (or magmatic vapors) is largely related to the modeling of geochemical processes including heterogeneous equilibrium calculations with variable bulk composition, temperature or pressure. With the aim to constrain the characteristics of extinct hydrothermal systems it is necessary to look for petrogenic evidence in active ones. The Kudryavy volcano in the Kurile Islands (Russia) provides a unique natural laboratory to study the formation of fumarolic rocks from high temperature fluids (measured temperature for the fumaroles up to 940 °C). By studying the minerals chemistry and assemblages and by computing a thermodynamical modeling, we investigated the mineralogical evidence for such high-temperature. We confirm the documented occurrence of Ca-Fe rich minerals as isolated patches, veins or incrustation in cavities and their formation during the alteration of primary minerals. We describe and documented secondary Na-Al rich minerals (davyne, nepheline, sodalite) and their occurrence together with Ca-Fe minerals in cavities. We also documented the presence of Fe-wollastonite, a relatively rare mineral suggesting high-T formation and we observed assemblages including wollastonite + andradite + magnetite suggesting high-temperature decomposition of andradite. This natural laboratory provides a series of concordant petrologic evidences for high-temperature fumarolic rocks and offers guidelines for the study of ancient high temperature hydrothermal environments on Earth and other planets like Mars.