What the study found
The study found that fast crystal growth in a submarine-quenched bomb from the 2022 Hunga eruption produced strong chemical and textural disequilibrium in microlites, which are very small crystals in magma. These disequilibria were stronger toward the bomb interior, where the melt was more evolved.
Why the authors say this matters
The authors conclude that far-from-equilibrium crystallization can distort estimates of magmatic timescales and thermobarometry, which uses mineral and melt compositions to estimate temperature and pressure. They also suggest that microlite-rich glass shards should be avoided when reconstructing pre-eruptive processes in mafic-intermediate systems.
What the researchers tested
The researchers used an intact submarine-quenched bomb from the 2022 Hunga eruption as a natural laboratory. They examined chemical and textural gradients across the bomb and used thermal modelling to infer crystallization kinetics and cooling history.
What worked and what didn't
High crystal growth rates were associated with increasing disequilibrium in clinopyroxene and plagioclase microlites toward the bomb interior. The authors report that the growth regime shifted from mainly interface-limited growth to diffusion-limited growth, and that the observed compositional trends could resemble pre-eruptive fractional crystallization.
What to keep in mind
The summary describes a single bomb, so the findings come from one natural example rather than many samples. The abstract does not provide additional limitations beyond the warning that syn- and post-eruptive crystallization can overprint magmatic signals.
Key points
- An intact submarine-quenched bomb from the 2022 Hunga eruption was analyzed.
- Microlite disequilibrium increased toward the bomb interior.
- Clinopyroxene and plagioclase microlites showed strong chemical and textural disequilibrium.
- The authors say constant experimentally derived crystal growth rates may not fit natural fast-cooling processes.
- Microlite-driven compositional trends could be mistaken for pre-eruptive fractional crystallization.
Disclosure
- Research title:
- Fast crystallization altered microlite and melt composition in a Hunga bomb
- Authors:
- Jie Wu, Alessio Pontesilli, Marco Brenna, Shane J. Cronin, Sung-Hyun Park, Joali Paredes‐Mariño, Kyle Hamilton, Marta Ribó, David Adams, Mila Huebsch
- Institutions:
- Auckland University of Technology, Istituto Nazionale di Geofisica e Vulcanologia, Korea Polar Research Institute, Queensland University of Technology, University of Auckland, University of Auckland, University of Auckland, University of Auckland, University of Auckland, University of Auckland, University of Otago, University of Otago
- Publication date:
- 2026-04-20
- OpenAlex record:
- View
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