Persistent high-pressure magma storage beneath a near-ridge ocean island volcano (Isla Floreana, Galápagos)

Gleeson, Matthew, Wieser, Penny, DeVitre, Charlotte L., Shi, Sarah C., Millet, Marc-Alban ORCID: https://orcid.org/0000-0003-2710-5374, Muir, Duncan D., Stock, Michael J. and Lissenberg, Johan ORCID: https://orcid.org/0000-0001-7774-2297 2025. Persistent high-pressure magma storage beneath a near-ridge ocean island volcano (Isla Floreana, Galápagos). Journal of Petrology , egaf031. 10.1093/petrology/egaf031

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Abstract

Volcanic evolution in ocean island settings is often controlled by variations in the chemistry and volumetric flux of magma from an underlying mantle plume. In locations such as Hawaiʻi or Réunion, this results in predictable variations in magma chemistry, the rate of volcanic activity, and the depth of magma storage with volcanic age and/or distance from the center of plume upwelling. These systems, however, represent outliers in global plume volcanism due to their high buoyancy flux, frequent eruptions, and large distance from any plate boundary. Most mantle plumes display clear interaction with nearby plate boundaries, influencing the dynamics of solid plume material in the upper mantle and the distribution of melt across regions of active volcanism. Yet, the influence of plume-ridge interaction and plume-ridge distance on the structure, characteristics, and evolution of magma storage beneath ocean island volcanoes remains under constrained. In this study, we consider the evolution of magmatic systems in the Galápagos Archipelago, a region of mantle plume volcanism located 150-250 km south of the Galápagos Spreading Centre (GSC), focusing on the depth of magma storage during the eastward transport of volcanic systems away from the centre of plume upwelling. Geochemical analysis of gabbro xenoliths from Isla Floreana in the south-eastern Galápagos suggest that they formed at ~2-2.5 Ma, when the island was located close to the centre of plume upwelling. These nodules, therefore, provide rare insights into the evolution of volcanic systems in the Galápagos Archipelago, tracking variations in the magma system architecture as the Nazca plate carried Isla Floreana eastwards, away from the plume centre.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Oxford University Press
ISSN:	0022-3530
Date of First Compliant Deposit:	4 April 2025
Date of Acceptance:	24 March 2025
Last Modified:	14 Apr 2025 13:30
URI:	https://orca.cardiff.ac.uk/id/eprint/177400

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