Epithermal clast coating inside the rock avalanche-debris flow deposits from Mount Meager Volcanic Complex, British Columbia (Canada)

Autor: Karine Bernard
Přispěvatelé: Laboratoire Magmas et Volcans (LMV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Institut national des sciences de l'Univers (INSU - CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Institut de Recherche pour le Développement et la société-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Journal of Volcanology and Geothermal Research
Journal of Volcanology and Geothermal Research, Elsevier, 2020, 402, pp.106994. ⟨10.1016/j.jvolgeores.2020.106994⟩
Journal of Volcanology and Geothermal Research, 2020, 402, pp.106994. ⟨10.1016/j.jvolgeores.2020.106994⟩
ISSN: 0377-0273
DOI: 10.1016/j.jvolgeores.2020.106994⟩
Popis: International audience; The observational and semi-quantitative sedimentological analyses of the lithofacies assemblage contribute to describe at different scales the breccia matrix along the sheared and transformed contact between rock avalanche deposits and trailing debris flow deposits emplaced by a large landslide at Mt. Meager volcano in British Columbia in 2010. An inverted cataclastic gradient of crushed breccias in a fluidized and mixed matrix implies a structurally controlled flow regime and rapid deposition. The coating matrix changed the initial polymodal distribution of the debris-flow lithofacies. Clast shape evolution helps to characterize the cataclastic sorting during transport and fluidized disaggregation. A plot of matrix percent against matrix/gravels helps to distinguish primary hot fracturing of about 61% from initial dilation and sheared fracturing involving ~22% matrix. Extensional disaggregation between 73 and 79% matrix is related to hydromagmatic fragmentation within an epithermal system. Clayey mineral assemblages identified by XRD patterns are related to colloidal aluminium gel, cataclastic shear bands, and quartz microstructures in epithermal breccia zones (pH = 2‐–3, 200‐–350 °C, 1500 °C); and 3) the secondary fracturing with flash heating and pressure pulse during cavitation (ΔP ~ 10 GPa, >1000‐–1500 °C), which generates pockets of partial melting, quartz spheroids, and a roll-over effect for the inner rim of coated clasts. The formation of impact melt breccias and the debris flow are related to the slowing elastic impact wave with an oscillatory relative speed during the inter-seismic period along a proximal strikeslip fault.This study helps identify how the proximal rock avalanche transformed into a highly mobile debris flow, larger examples of which pose a hazard to the town of Pemberton, at a distance of 65 km from Mt. Meager.
Databáze: OpenAIRE
Externí odkaz: