Ti3+ in corundum traces crystal growth in a highly reduced magma

Abstract Aggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental Al2O3-supersaturated melt; phenocrysts of tistarite (Ti2O3) in t...

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Autores principales:	Beñat Oliveira, William L. Griffin, Sarah E. M. Gain, Martin Saunders, Jeremy Shaw, Vered Toledo, Juan Carlos Afonso, Suzanne Y. O’Reilly
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1e8a15b9cc2342f99d6e74569ccc1103
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spelling	oai:doaj.org-article:1e8a15b9cc2342f99d6e74569ccc11032021-12-02T10:47:54ZTi3+ in corundum traces crystal growth in a highly reduced magma10.1038/s41598-020-79739-42045-2322https://doaj.org/article/1e8a15b9cc2342f99d6e74569ccc11032021-01-01T00:00:00Zhttps://doi.org/10.1038/s41598-020-79739-4https://doaj.org/toc/2045-2322Abstract Aggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental Al2O3-supersaturated melt; phenocrysts of tistarite (Ti2O3) in the trapped melts indicate crystallization at oxygen fugacities 6–7 log units below the Iron-Wüstite buffer (fO2 = ΔIW − 6 to − 7), induced by fluxes of mantle-derived CH4-H2 fluids. Cathodoluminescence images reveal growth zoning within the individual crystals of the aggregates, related to the substitution of Ti3+ in the corundum structure. Ti contents are < 0.3 wt% initially, then increase first linearly, then exponentially, toward adjacent melt pockets to reach values > 2 wt%. Numerical modelling indicates that the first skeletal crystals grew in an open system, from a moving magma. The subsequent linear increase in Ti reflects growth in a partially closed system, with decreasing porosity; the exponential increase in Ti close to melt pockets reflects closed-system growth, leading to dramatic increases in incompatible-element concentrations in the residual melts. We suggest that the corundum aggregates grew in melt/fluid conduits; diffusion modelling implies timescales of days to years before crystallization was terminated by explosive eruption. These processes probably operate in explosive volcanic systems in several tectonic settings.Beñat OliveiraWilliam L. GriffinSarah E. M. GainMartin SaundersJeremy ShawVered ToledoJuan Carlos AfonsoSuzanne Y. O’ReillyNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Beñat Oliveira William L. Griffin Sarah E. M. Gain Martin Saunders Jeremy Shaw Vered Toledo Juan Carlos Afonso Suzanne Y. O’Reilly Ti3+ in corundum traces crystal growth in a highly reduced magma
description	Abstract Aggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental Al2O3-supersaturated melt; phenocrysts of tistarite (Ti2O3) in the trapped melts indicate crystallization at oxygen fugacities 6–7 log units below the Iron-Wüstite buffer (fO2 = ΔIW − 6 to − 7), induced by fluxes of mantle-derived CH4-H2 fluids. Cathodoluminescence images reveal growth zoning within the individual crystals of the aggregates, related to the substitution of Ti3+ in the corundum structure. Ti contents are < 0.3 wt% initially, then increase first linearly, then exponentially, toward adjacent melt pockets to reach values > 2 wt%. Numerical modelling indicates that the first skeletal crystals grew in an open system, from a moving magma. The subsequent linear increase in Ti reflects growth in a partially closed system, with decreasing porosity; the exponential increase in Ti close to melt pockets reflects closed-system growth, leading to dramatic increases in incompatible-element concentrations in the residual melts. We suggest that the corundum aggregates grew in melt/fluid conduits; diffusion modelling implies timescales of days to years before crystallization was terminated by explosive eruption. These processes probably operate in explosive volcanic systems in several tectonic settings.
format	article
author	Beñat Oliveira William L. Griffin Sarah E. M. Gain Martin Saunders Jeremy Shaw Vered Toledo Juan Carlos Afonso Suzanne Y. O’Reilly
author_facet	Beñat Oliveira William L. Griffin Sarah E. M. Gain Martin Saunders Jeremy Shaw Vered Toledo Juan Carlos Afonso Suzanne Y. O’Reilly
author_sort	Beñat Oliveira
title	Ti3+ in corundum traces crystal growth in a highly reduced magma
title_short	Ti3+ in corundum traces crystal growth in a highly reduced magma
title_full	Ti3+ in corundum traces crystal growth in a highly reduced magma
title_fullStr	Ti3+ in corundum traces crystal growth in a highly reduced magma
title_full_unstemmed	Ti3+ in corundum traces crystal growth in a highly reduced magma
title_sort	ti3+ in corundum traces crystal growth in a highly reduced magma
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/1e8a15b9cc2342f99d6e74569ccc1103
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Ti3+ in corundum traces crystal growth in a highly reduced magma

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