An official website of the United States government
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.
more »
« less
This content will become publicly available on December 1, 2025
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.
more »
« less
- 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
More Like this
-
-
Abstract Water or acid soaking surface treatments have been shown to increase the mechanical strength of soda‐lime silicate (SLS) glasses. This increase in strength has traditionally been attributed to effects related to residual stress or changes in fracture resistance. In this work, we report experimental data that cannot be explained based on the existing knowledge of glass surface mechanics. In dry environments, annealed and acid‐leached SLS surfaces have comparable crack initiation stress and fracture stress as measured by Hertzian indentation and biaxial bending tests, respectively. Yet, in the presence of humidity, acid‐leached surfaces have higher failure stress than the annealed surfaces. This apparent enhancement in the crack resistance of the acid‐leached surface of SLS glass in humid environments supports the hypothesis that acid‐leached surface chemistry can lower the transport kinetics of molecular water to critical flaws.more » « less
-
Significance Ice-nucleating particles significantly alter cloud properties and lifetime, causing large but poorly constrained climate impacts. Biomass-burning aerosol emitted by wildfires is a major and growing source of atmospheric pollution. Prior work suggested that ice-nucleating particles can sometimes be emitted by biomass combustion, but the production and characteristics of these particles are poorly understood. Here we show that mineral phases are a significant ice-active component of both biomass-burning aerosol and ash particles. These mineral phases are derived from plant inorganic material that decomposes and reforms as ice-active minerals during combustion; they form more commonly from tall grass versus wood fuels. Aerosolized mineral and ash are now understood as a major source of the ice-nucleating particles in biomass-burning smoke.more » « less
-
Bahadori, Alireza (Ed.)Article Published: 27 May 2024 Explosive 2018 eruptions at Kīlauea driven by a collapse-induced stomp-rocket mechanism Josh Crozier, Josef Dufek, Leif Karlstrom, Kyle R. Anderson, Ryan Cahalan, Weston Thelen, Mary Benage & Chao Liang Nature Geoscience volume 17, pages572–578 (2024)Cite this article 1357 Accesses 430 Altmetric Metricsdetails Abstract Explosive volcanic eruptions produce hazardous atmospheric plumes composed of tephra particles, hot gas and entrained air. Such eruptions are generally driven by magmatic fragmentation or steam expansion. However, an eruption mechanism outside this phreatic–magmatic spectrum was suggested by a sequence of 12 explosive eruptions in May 2018 at Kīlauea, Hawaii, that occurred during the early stages of caldera collapse and produced atmospheric plumes reaching 8 km above the vent. Here we use seismic inversions for reservoir pressure as a source condition for three-dimensional simulations of transient multiphase eruptive plume ascent through a conduit and stratified atmosphere. We compare the simulations with conduit ascent times inferred from seismic and infrasound data, and with plume heights from radar data. We find that the plumes are consistent with eruptions caused by a stomp-rocket mechanism involving the abrupt subsidence of reservoir roof rock that increased pressure in the underlying magma reservoir. In our model, the reservoir was overlain by a pocket of accumulated high-temperature magmatic gas and lithic debris, which were driven through a conduit approximately 600 m long to erupt particles at rates of around 3,000 m3 s−1. Our results reveal a distinct collapse-driven type of eruption and provide a framework for integrating diverse geophysical and atmospheric data with simulations to gain a better understanding of unsteady explosive eruptions.more » « less
-
Environmental contextIron-containing combustion particles are likely to contribute to environmental iron deposition, while atmospheric acidic processing of such particles can promote their dissolution. Here we report the surface-mediated dissolution of iron from ashes generated by biomass burning power plants and kilns. Examination of the dissolution process at several environmentally relevant pHs, suggests that pH has little impact on the fraction of bioavailable Fe(II) that dissolves into the aqueous phase, although Fe(III) is heavily pH dependent. RationaleAnthropogenic combustion particles, such as ash produced in power plants or kilns, are byproducts with limited use that accumulate in large deposits and become materials of environmental concern. While stored, these particles can be carried by winds into the atmosphere or into soil or near water bodies. Recent studies suggest that a fraction of metals present in the environment come from combustion particles. MethodologyIn this study, we carry out a comparative study of iron dissolution and speciation from two different combustion particles: bottom ash from a biomass-fired power plant (BA) and lime kiln dust (LKD). Samples were fully characterised and their iron leaching was investigated in aqueous suspensions under environmentally relevant acidic conditions. Iron analysis and speciation was carried out calorimetrically. ResultsFor the combustion particles examined, the fraction of bioavailable Fe2+ is lower than Fe3+. The solubility of Fe3+ is highly dependent on pH, dropping significantly at pHs higher than 3. On the other hand, the solubility of Fe2+ from both BA and LKD was found to be relatively constant over the range of pH investigated. DiscussionIron availability from combustion particles with similar mineralogy is driven by the particle’s surface properties. While iron from LKD dissolves faster than that from BA, the initial rate of dissolution of iron remains statistically constant at pHs relevant for the atmospheric aerosol deliquescent layer, decreasing at pHs above 3. This work provides insight into the ability of combustion particles to provide iron micronutrients under different environmentally relevant acidic conditions.more » « less
