A 4D view on the evolution of metamorphic dehydration reactions

Abstract Metamorphic reactions influence the evolution of the Earth’s crust in a range of tectonic settings. For example hydrous mineral dehydration in a subducting slab can produce fluid overpressures which may trigger seismicity. During reaction the mechanisms of chemical transport, including wate...

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Autores principales:	John Bedford, Florian Fusseis, Henri Leclère, John Wheeler, Daniel Faulkner
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b343e9641c7d474e8aa7dc5bba66fdcf
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spelling	oai:doaj.org-article:b343e9641c7d474e8aa7dc5bba66fdcf2021-12-02T16:08:12ZA 4D view on the evolution of metamorphic dehydration reactions10.1038/s41598-017-07160-52045-2322https://doaj.org/article/b343e9641c7d474e8aa7dc5bba66fdcf2017-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-07160-5https://doaj.org/toc/2045-2322Abstract Metamorphic reactions influence the evolution of the Earth’s crust in a range of tectonic settings. For example hydrous mineral dehydration in a subducting slab can produce fluid overpressures which may trigger seismicity. During reaction the mechanisms of chemical transport, including water expulsion, will dictate the rate of transformation and hence the evolution of physical properties such as fluid pressure. Despite the importance of such processes, direct observation of mineral changes due to chemical transport during metamorphism has been previously impossible both in nature and in experiment. Using time-resolved (4D) synchrotron X-ray microtomography we have imaged a complete metamorphic reaction and show how chemical transport evolves during reaction. We analyse the dehydration of gypsum to form bassanite and H2O which, like most dehydration reactions, produces a solid volume reduction leading to the formation of pore space. This porosity surrounds new bassanite grains producing fluid-filled moats, across which transport of dissolved ions to the growing grains occurs via diffusion. As moats grow in width, diffusion and hence reaction rate slow down. Our results demonstrate how, with new insights into the chemical transport mechanisms, we can move towards a more fundamental understanding of the hydraulic and chemical evolution of natural dehydrating systems.John BedfordFlorian FusseisHenri LeclèreJohn WheelerDaniel FaulknerNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-7 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q John Bedford Florian Fusseis Henri Leclère John Wheeler Daniel Faulkner A 4D view on the evolution of metamorphic dehydration reactions
description	Abstract Metamorphic reactions influence the evolution of the Earth’s crust in a range of tectonic settings. For example hydrous mineral dehydration in a subducting slab can produce fluid overpressures which may trigger seismicity. During reaction the mechanisms of chemical transport, including water expulsion, will dictate the rate of transformation and hence the evolution of physical properties such as fluid pressure. Despite the importance of such processes, direct observation of mineral changes due to chemical transport during metamorphism has been previously impossible both in nature and in experiment. Using time-resolved (4D) synchrotron X-ray microtomography we have imaged a complete metamorphic reaction and show how chemical transport evolves during reaction. We analyse the dehydration of gypsum to form bassanite and H2O which, like most dehydration reactions, produces a solid volume reduction leading to the formation of pore space. This porosity surrounds new bassanite grains producing fluid-filled moats, across which transport of dissolved ions to the growing grains occurs via diffusion. As moats grow in width, diffusion and hence reaction rate slow down. Our results demonstrate how, with new insights into the chemical transport mechanisms, we can move towards a more fundamental understanding of the hydraulic and chemical evolution of natural dehydrating systems.
format	article
author	John Bedford Florian Fusseis Henri Leclère John Wheeler Daniel Faulkner
author_facet	John Bedford Florian Fusseis Henri Leclère John Wheeler Daniel Faulkner
author_sort	John Bedford
title	A 4D view on the evolution of metamorphic dehydration reactions
title_short	A 4D view on the evolution of metamorphic dehydration reactions
title_full	A 4D view on the evolution of metamorphic dehydration reactions
title_fullStr	A 4D view on the evolution of metamorphic dehydration reactions
title_full_unstemmed	A 4D view on the evolution of metamorphic dehydration reactions
title_sort	4d view on the evolution of metamorphic dehydration reactions
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/b343e9641c7d474e8aa7dc5bba66fdcf
work_keys_str_mv	AT johnbedford a4dviewontheevolutionofmetamorphicdehydrationreactions AT florianfusseis a4dviewontheevolutionofmetamorphicdehydrationreactions AT henrileclere a4dviewontheevolutionofmetamorphicdehydrationreactions AT johnwheeler a4dviewontheevolutionofmetamorphicdehydrationreactions AT danielfaulkner a4dviewontheevolutionofmetamorphicdehydrationreactions AT johnbedford 4dviewontheevolutionofmetamorphicdehydrationreactions AT florianfusseis 4dviewontheevolutionofmetamorphicdehydrationreactions AT henrileclere 4dviewontheevolutionofmetamorphicdehydrationreactions AT johnwheeler 4dviewontheevolutionofmetamorphicdehydrationreactions AT danielfaulkner 4dviewontheevolutionofmetamorphicdehydrationreactions
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A 4D view on the evolution of metamorphic dehydration reactions

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