Annual-to-millennial fluctuations in the physical properties of crystal-rich magma storage zones

Oliver Higgins; Michael J. Stock; Dennis Geist; David A. Neave; Iris Buisman; Benjamin Bernard; Matthew Gleeson

doi:10.1038/s43247-025-02982-y

Annual-to-millennial fluctuations in the physical properties of crystal-rich magma storage zones

Oliver Higgins^*
, Michael J. Stock
, Dennis Geist
, David A. Neave
, Iris Buisman
, Benjamin Bernard
, Matthew Gleeson

^*Corresponding author for this work

School of Earth & Environmental Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

Basaltic melts may variably disaggregate macrocrysts (large crystals) from crystal mushes during the assembly of magma bodies beneath ocean-island volcanoes. The entrained macrocrysts modulate the crystallinity, density, and rheology of magmas, parameters that control magma system architecture and eruptive dynamics. However, the timescales, drivers, and consequences of inconstant crystal mush incorporation into carrier melts require quantification. Here, we use a suite of plagioclase-rich basalts to show that the entrainment efficiency (the ability for melts to disaggregate and entrain macrocrysts from crystal mushes) is temporally variable on inter-eruption timescales at ocean-island volcanoes. Macrocryst cargoes are predominantly out of equilibrium with their carrier melts in both chemistries and mass proportions (ratios of different macrocryst phases). Geochemical and petrological evidence reveals that macrocryst mass proportions are established in a density-stratified melt-rich reservoir shortly before eruption, whereas the absolute crystallinity is a function of crustal physics, likely driven by fluctuations of annual-to-millennial melt supply. Variations in entrainment efficiency explain several universal, but enigmatic, features in oceanic volcanic systems, such as decoupled crystallinity–temperature–time relationships and the dearth of plagioclase-rich basalts at fast-spreading mid-ocean ridges. Systematically studying temporally constrained eruptive products offers a unique window into the evolution of crystal-rich magma storage zones.

Original language	English
Article number	1033
Journal	Communications Earth & Environment
Volume	6
Issue number	1
Early online date	20 Nov 2025
DOIs	https://doi.org/10.1038/s43247-025-02982-y
Publication status	Published - 24 Dec 2025

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Supplementary material, code, and raw data for Higgins et al
Higgins, O. (Creator), Figshare, 2025
DOI: 10.6084/m9.figshare.30401920
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@article{58e27cb8c4414d1f967e5206fde38ce7,

title = "Annual-to-millennial fluctuations in the physical properties of crystal-rich magma storage zones",

abstract = "Basaltic melts may variably disaggregate macrocrysts (large crystals) from crystal mushes during the assembly of magma bodies beneath ocean-island volcanoes. The entrained macrocrysts modulate the crystallinity, density, and rheology of magmas, parameters that control magma system architecture and eruptive dynamics. However, the timescales, drivers, and consequences of inconstant crystal mush incorporation into carrier melts require quantification. Here, we use a suite of plagioclase-rich basalts to show that the entrainment efficiency (the ability for melts to disaggregate and entrain macrocrysts from crystal mushes) is temporally variable on inter-eruption timescales at ocean-island volcanoes. Macrocryst cargoes are predominantly out of equilibrium with their carrier melts in both chemistries and mass proportions (ratios of different macrocryst phases). Geochemical and petrological evidence reveals that macrocryst mass proportions are established in a density-stratified melt-rich reservoir shortly before eruption, whereas the absolute crystallinity is a function of crustal physics, likely driven by fluctuations of annual-to-millennial melt supply. Variations in entrainment efficiency explain several universal, but enigmatic, features in oceanic volcanic systems, such as decoupled crystallinity–temperature–time relationships and the dearth of plagioclase-rich basalts at fast-spreading mid-ocean ridges. Systematically studying temporally constrained eruptive products offers a unique window into the evolution of crystal-rich magma storage zones.",

author = "Oliver Higgins and Stock, \{Michael J.\} and Dennis Geist and Neave, \{David A.\} and Iris Buisman and Benjamin Bernard and Matthew Gleeson",

note = "Funding: Oliver Higgins would like to gratefully acknowledge the Swiss National Science Foundation for funding through an Early Postdoctoral Mobility Fellowship (Project Number: P500PN\_210239). This publication has emanated from research supported in part by a research grant from Science Foundation Ireland and the Geological Survey of Ireland under the SFI Frontiers for the Future Programme 20/FFP-P/8895, and a Charles Darwin and Gal{\'a}pagos Islands Junior Research Fellowship at Christ{\textquoteright}s College, Cambridge (awarded to M.J.S.). Additional fieldwork funding was provided by the Jeremy Willson Charitable Trust (administered by the Geological Society of London) and the Mineralogical Society of Great Britain and Ireland. David Neave acknowledges contributions from a NERC grant (NE/T011106/1). Dennis Geist{\textquoteright}s work was supported by the U.S. National Science Foundation.",

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month = dec,

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doi = "10.1038/s43247-025-02982-y",

language = "English",

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T1 - Annual-to-millennial fluctuations in the physical properties of crystal-rich magma storage zones

AU - Higgins, Oliver

AU - Stock, Michael J.

AU - Geist, Dennis

AU - Neave, David A.

AU - Buisman, Iris

AU - Bernard, Benjamin

AU - Gleeson, Matthew

N1 - Funding: Oliver Higgins would like to gratefully acknowledge the Swiss National Science Foundation for funding through an Early Postdoctoral Mobility Fellowship (Project Number: P500PN_210239). This publication has emanated from research supported in part by a research grant from Science Foundation Ireland and the Geological Survey of Ireland under the SFI Frontiers for the Future Programme 20/FFP-P/8895, and a Charles Darwin and Galápagos Islands Junior Research Fellowship at Christ’s College, Cambridge (awarded to M.J.S.). Additional fieldwork funding was provided by the Jeremy Willson Charitable Trust (administered by the Geological Society of London) and the Mineralogical Society of Great Britain and Ireland. David Neave acknowledges contributions from a NERC grant (NE/T011106/1). Dennis Geist’s work was supported by the U.S. National Science Foundation.

PY - 2025/12/24

Y1 - 2025/12/24

N2 - Basaltic melts may variably disaggregate macrocrysts (large crystals) from crystal mushes during the assembly of magma bodies beneath ocean-island volcanoes. The entrained macrocrysts modulate the crystallinity, density, and rheology of magmas, parameters that control magma system architecture and eruptive dynamics. However, the timescales, drivers, and consequences of inconstant crystal mush incorporation into carrier melts require quantification. Here, we use a suite of plagioclase-rich basalts to show that the entrainment efficiency (the ability for melts to disaggregate and entrain macrocrysts from crystal mushes) is temporally variable on inter-eruption timescales at ocean-island volcanoes. Macrocryst cargoes are predominantly out of equilibrium with their carrier melts in both chemistries and mass proportions (ratios of different macrocryst phases). Geochemical and petrological evidence reveals that macrocryst mass proportions are established in a density-stratified melt-rich reservoir shortly before eruption, whereas the absolute crystallinity is a function of crustal physics, likely driven by fluctuations of annual-to-millennial melt supply. Variations in entrainment efficiency explain several universal, but enigmatic, features in oceanic volcanic systems, such as decoupled crystallinity–temperature–time relationships and the dearth of plagioclase-rich basalts at fast-spreading mid-ocean ridges. Systematically studying temporally constrained eruptive products offers a unique window into the evolution of crystal-rich magma storage zones.

AB - Basaltic melts may variably disaggregate macrocrysts (large crystals) from crystal mushes during the assembly of magma bodies beneath ocean-island volcanoes. The entrained macrocrysts modulate the crystallinity, density, and rheology of magmas, parameters that control magma system architecture and eruptive dynamics. However, the timescales, drivers, and consequences of inconstant crystal mush incorporation into carrier melts require quantification. Here, we use a suite of plagioclase-rich basalts to show that the entrainment efficiency (the ability for melts to disaggregate and entrain macrocrysts from crystal mushes) is temporally variable on inter-eruption timescales at ocean-island volcanoes. Macrocryst cargoes are predominantly out of equilibrium with their carrier melts in both chemistries and mass proportions (ratios of different macrocryst phases). Geochemical and petrological evidence reveals that macrocryst mass proportions are established in a density-stratified melt-rich reservoir shortly before eruption, whereas the absolute crystallinity is a function of crustal physics, likely driven by fluctuations of annual-to-millennial melt supply. Variations in entrainment efficiency explain several universal, but enigmatic, features in oceanic volcanic systems, such as decoupled crystallinity–temperature–time relationships and the dearth of plagioclase-rich basalts at fast-spreading mid-ocean ridges. Systematically studying temporally constrained eruptive products offers a unique window into the evolution of crystal-rich magma storage zones.

U2 - 10.1038/s43247-025-02982-y

DO - 10.1038/s43247-025-02982-y

M3 - Article

SN - 2662-4435

VL - 6

JO - Communications Earth & Environment

JF - Communications Earth & Environment

IS - 1

M1 - 1033

ER -

Annual-to-millennial fluctuations in the physical properties of crystal-rich magma storage zones

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