Plug flow and brecciation in volcanic conduits can emerge from shear-induced crystal migration in otherwise Newtonian magmas

Vasseur, Jérémie; Wadsworth, Fabian B.; Dingwell, Donald B.; Lavallée, Yan

Abstract

In the Earth, the flow of crystal-bearing magma is thought to be non-Newtonian and shear thinning, but the physical origin for this is poorly understood. We use hydro-granular theory to show that the decoupled migration of crystals toward conduit cores during magma ascent is a tenable microphysical mechanism for plug flow, emergent in an otherwise purely Newtonian crystal-bearing magma. We use a numerical conduit model to define the flow development length beyond which crystal migration dominates and strain localises near conduit margins. Applied to magma ascent scenarios, we show that this crystal-migration strain localisation only develops in high crystallinity magmas or magmas ascending in very narrow cracks/conduits. In all other scenarios, crystals do not contribute to non-Newtonian behaviour and such magmas are usually strictly Newtonian. The ascent of very crystal-rich dome magma could be associated with strain localisation and crystal depletion at the conduit margins, lubricating ascent through the crust.

Citation

Vasseur, J., Wadsworth, F. B., Dingwell, D. B., & Lavallée, Y. (2024). Plug flow and brecciation in volcanic conduits can emerge from shear-induced crystal migration in otherwise Newtonian magmas. Communications Earth & Environment, 5(1), Article 389. https://doi.org/10.1038/s43247-024-01556-8

• Journal Article Type: Article
• Acceptance Date: Jul 1, 2024
• Online Publication Date: Jul 20, 2024
• Publication Date: Jul 20, 2024
• Deposit Date: Aug 6, 2024
• Publicly Available Date: Aug 6, 2024
• Journal: Communications Earth & Environment
• Electronic ISSN: 2662-4435
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 5
• Issue: 1
• Article Number: 389
• DOI: https://doi.org/10.1038/s43247-024-01556-8
• Public URL: https://durham-repository.worktribe.com/output/2614954