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When magmas erupt at the surface, they may have undergone many changes since their inception. While olivine drives some of these changes through crystallization and fractionation, it also records the magma evolution via mineral chemistry and by trapping mineral and melt inclusions. Olivine is an effective recorder of intensive parameters, such as temperature and melt composition, and provides an outstanding petrological tool for constraining dynamic processes, such as ascent, mixing, and cooling. Olivine sheds light on magmatic puzzles that involve both mafic and more evolved magmas, with protracted and complex magmatic histories that often obscure earlier and deeper processes. This contribution summarizes the current state of how olivine helps reconstruct source-to-surface magma assembly through its chemistry, inclusions, and textures.
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Nanoscale silicate melt textures determine volcanic ash surface chemistry
Abstract Explosive volcanic eruptions produce vast quantities of silicate ash, whose surfaces are subsequently altered during atmospheric transit. These altered surfaces mediate environmental interactions, including atmospheric ice nucleation, and toxic effects in biota. A lack of knowledge of the initial, pre-altered ash surface has required previous studies to assume that the ash surface composition created during magmatic fragmentation is equivalent to the bulk particle assemblage. Here we examine ash particles generated by controlled fragmentation of andesite and find that fragmentation generates ash particles with substantial differences in surface chemistry. We attribute this disparity to observations of nanoscale melt heterogeneities, in which Fe-rich nanophases in the magmatic melt deflect and blunt fractures, thereby focusing fracture propagation within aureoles of single-phase melt formed during diffusion-limited growth of crystals. In this manner, we argue that commonly observed pre-eruptive microtextures caused by disequilibrium crystallisation and/or melt unmixing can modify fracture propagation and generate primary discrepancies in ash surface chemistry, an essential consideration for understanding the cascading consequences of reactive ash surfaces in various environments.
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- Award ID(s):
- 1719875
- PAR ID:
- 10549146
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 15
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-024-44712-6
