Stratigraphically controlled sampling captures the onset of highly fluid-fluxed melting at San Jorge volcano, Southern Volcanic Zone, Chile

McGee, Lucy; Morgado, Eduardo; Brahm, Raimundo; Parada, Miguel A.; Vinet, Nicolas; Lara, Luis E.; Flores, Andrés; Turner, Michael; Handley, Heather; Nowell, Geoff

doi:10.1007/s00410-019-1643-x

Cited by 7 publications

(2 citation statements)

References 82 publications

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“…Small-volume and short-lived eruptions may display a wide spectrum of chemical compositions controlled by magma evolution and ascent processes within the plumbing system (Brenna et al, 2021;McGee et al, 2019). At Hunga volcano, negligible chemical variability in the two recent successive eruptions, five years apart, as well as the homogeneity throughout each eruption implies no differentiation of the melts during ascent to eruption.…”

Section: Post-caldera Magmatic Activitymentioning

confidence: 99%

Post-caldera volcanism reveals shallow priming of an intra-ocean arc andesitic caldera: Hunga volcano, Tonga, SW Pacific

Brenna¹,

Cronin²,

Smith³

et al. 2022

Preprint

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Intra-oceanic arcs are typically associated with intermediate (andesitic) cone volcanoes. However, caldera volcanoes may also form in these settings from very large eruptions, resulting in sudden changes to the magma reservoir. These reservoirs can then produce eithersemi-continuous or intermittent low-intensity volcanism between major caldera-producing or caldera-deepening eruptions, providing insights into the post-caldera evolution of the system. Hunga volcano (Kingdom of Tonga, Southwest Pacific) is a large mainly submarine edificethat produced a series of caldera-forming eruptions ~900 years ago. Since then, numerous smaller-scale subaerial and submarine eruptions occurred, the most recent forming new islands in 2009 and 2014/15. Pyroclastic deposits associated with these latest eruptions have identical(range ~0.1 wt.% of all major oxides) andesitic composition that overlap with the primitive end of the slightly wider compositional range of the caldera-forming episodes. Texturally simple plagioclase, clinopyroxene and orthopyroxene phenocrysts in pre-, syn- and post-caldera pyroclasts point to a single shallow storage reservoir at 5–8 km depth. Lack of complex zonation indicates that this reservoir is constantly resupplied by low-flux inputs of basaltic andesite magma and is large enough that convective mixing rapidly homogenises new inputs. The reservoir feeds intermittent, low-intensity, post-caldera volcanism with constant andesite composition, driven possibly by magmatic overpressure and “leakage” of gas-rich magma pockets around the edges of the caldera. More primitive and compositionally variable basaltic andesites formed a lava-dominated edifice prior to the caldera-forming event. This suggests a causal link between magma supply dynamics and caldera priming relating to the maturing of the plumbing system and formation of a sustained subvolcanic andesite magma reservoir.

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Section: Post-caldera Magmatic Activitymentioning

confidence: 99%

Post-caldera volcanism reveals shallow priming of an intra-ocean arc andesitic caldera: Hunga volcano, Tonga, SW Pacific

Brenna¹,

Cronin²,

Smith³

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…Documenting of the changes in bulk-rock and crystal chemistry with eruption sequence (e.g. Brenna et al 2010 andMcGee et al 2019) may reveal whether the eruption sequentially tapped the reservoir from top to bottom, whether magmas from a range of depths of the plumbing system where . Such relationships could be used when studying natural systems that may have sampled the complete reservoir in an eruption sequence, and for which it can be shown that the crystal zoning is due to diffusion.…”

Section: Effect Of the Eruption On Sampling Of The Plumbing System And Crystal Diffusion Timesmentioning

confidence: 99%

Linking fluid dynamics and olivine crystal scale zoning during simulated magma intrusion

Cheng

Costa

Bergantz

2020

Contrib Mineral Petrol

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The compositional zoning styles of natural crystals produced during magma intrusion can be used to investigate the structure of magmatic plumbing systems and its relation to expressions of volcanic unrest (seismic, deformation, volatiles). However, magma intrusion is a progressive, dynamic process and yields non-monotonic heterogeneities in physio-chemical variables such as complex spatial variations in temperature and liquid composition with time. Such changes in variables are difficult to incorporate in models of crystal zoning in natural systems. Here we take another approach by integrating the results of a numerical multiphase simulation of melt arrival in an olivine-rich reservoir with models of chemical re-equilibration of olivine. We evaluate the diversity of chemical zoning styles and the inferred time scales using Fe–Mg diffusion in olivine for a limited range of system geometries and time-composition-temperature values. Although our models are still a large simplification of the processes that may occur in natural systems we find several time-dependent and systematic relations between variables that can be used to better interpret natural data. The proportions of zoned and unzoned crystals, the zoning length scales, and the calculated diffusion times from the crystals, vary with time and the initial position of the crystal in the reservoir. These relationships can be used, for example, to better constrain the plumbing structure and dynamics of mafic eruptions from monogenetic volcanoes by detailed studies of changes in the zoning of the crystal cargo with eruptive sequence. Moreover, we also find that the time scales obtained from modeling of crystals at a single temperature and boundary condition tend to be shorter (> about 25%) than the residence time, which could also be tested in natural studies by combining crystal time scale records with monitoring datasets.

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Upper crustal differentiation processes and their role in 238U-230Th disequilibria at the San Pedro-Linzor volcanic chain (Central Andes)

Godoy

McGee

González-Maurel

et al. 2020

Journal of South American Earth Sciences

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Stratigraphically controlled sampling captures the onset of highly fluid-fluxed melting at San Jorge volcano, Southern Volcanic Zone, Chile

Cited by 7 publications

References 82 publications

Post-caldera volcanism reveals shallow priming of an intra-ocean arc andesitic caldera: Hunga volcano, Tonga, SW Pacific

Post-caldera volcanism reveals shallow priming of an intra-ocean arc andesitic caldera: Hunga volcano, Tonga, SW Pacific

Linking fluid dynamics and olivine crystal scale zoning during simulated magma intrusion

Upper crustal differentiation processes and their role in 238U-230Th disequilibria at the San Pedro-Linzor volcanic chain (Central Andes)

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