ORCID

Abstract

Mineral reaction textures are fundamental archives of geological change. Amphibole reaction rims are among the most widely used to reconstruct pre-eruptive magmatic conditions, traditionally interpreted through changes in pressure, temperature and melt composition. However, these interpretations have largely overlooked the role of deformation, ubiquitous during magma ascent. Here we show that amphibole breakdown is not only thermodynamically sensitive, but also mechanically sensitive. Using electron backscatter diffraction (EBSD) analyses of experimental and natural samples, combined with numerical simulations of crystal rotation under magma flow, we demonstrate that pyroxene nucleates topotactically on amphibole, forming rims, but can later reorient in response to strain. In static experiments, gravitational settling alone produces measurable misorientations that can be tracked over time, while natural samples reveal signatures of externally imposed shear. The resulting rim textures encode evolving strain histories, with crystal misorientation distributions tracking both total strain and variations in rim crystallisation and/or deformation rates. With EBSD-derived crystal orientations now shown to capture both thermodynamic and mechanical histories, amphibole reaction rims emerge as four-dimensional petrological recorders, sensitive to pressure, temperature, composition and strain (P–T–X–ε), providing a powerful unified framework for reconstructing magma evolution and the mechanics of magma transport.

Publication Date

2026-04-09

Publication Title

Nature Communications

Volume

17

Issue

1

ISSN

2041-1723

Acceptance Date

2026-03-23

Deposit Date

2026-04-30

Funding

We thank the VUELCO team for their invaluable field assistance during a 2012 sampling campaign at Soufrière Hills Volcano. For Unzen volcano samples, we gratefully acknowledge Takahiro Miwa and Hiroyuki Shimizu for field assistance during a 2016 campaign, along with funding provided by the Daiwa Anglo-Japanese Foundation Award (grant number 11000/11740). Pavel Izbekov is thanked for generously providing samples from Bezymianny volcano (funded by PIRE-Kamchatka, NSF OISE-0530278), and Shanika De Silva for insightful discussions and supplying samples from El Misti volcano. Their contributions were essential to the completion of this study. P.A.W., A.L., J.E.K. and Y.L. acknowledge support from the LMUexcellent fund, funded by the Federal Ministry of Education and Research (BMBF) and the Free State of Bavaria under the Excellence Strategy of the Federal Government and the Länder. J.L. acknowledges a National Science Foundation (NSF) grant no. EAR-1650185. Y.L. and J.B. acknowledge support from the European Research Council (ERC) MODERATE project grant no. 101001065. The EBSD-SEM laboratory at the University of Liverpool (now the scanning electron microscopy shared research facility-SEM SRF) is acknowledged for supporting EBSD analyses.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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Additional Files

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