Old magma and a new, intrusive trigger: using diffusion chronometry to understand the rapid-onset Calbuco eruption, April 2015 (Southern Chile)
Author
dc.contributor.author
Morgado, Eduardo
Author
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Morgan, Daniel J.
Author
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Castruccio, Angelo
Author
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Ebmeier, Susanna K.
Author
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Parada, Miguel Ángel
Author
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Brahm Scott, Raimundo
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Harvey, Jason
Author
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Gutiérrez, Francisco
Author
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Walshaw, Richard
Admission date
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2019-10-30T15:23:58Z
Available date
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2019-10-30T15:23:58Z
Publication date
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2019
Cita de ítem
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Contributions to Mineralogy and Petrology, Volumen 174, Issue 7, 2019,
Identifier
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00107999
Identifier
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10.1007/s00410-019-1596-0
Identifier
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https://repositorio.uchile.cl/handle/2250/172377
Abstract
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In April 2015, an unpredicted rapid-onset eruption occurred at Calbuco Volcano, Southern Andes of Chile. This event consisted of two, sub-Plinian eruptions separated by a few hours. By analysis of Fe–Ti exchange between ilmenite and titanomagnetite crystals in samples of erupted material, we determine timescales of pre-eruptive heating experienced at the partially solidified chamber base and constrain the magma residence time for the bulk of the carrier magma. Analysis of the Fe–Ti oxide pairs from a sample retrieved from a pyroclastic density current deposit (Cal-160) shows that it was affected by a significant heating event (recording 70–220 °C of heating), while other collected samples did not record this late heating. This sample is interpreted to represent a piece of crystal mush located at the bottom of a prolate, ellipsoidal mush reservoir, mobilised < 4 days before the eruption by a triggering pulse of mafic magma considerably hotter than the typical magmatic temperature of the reservoir. Another two fall deposit samples (lapillus, Cal-149Tb and Cal-155) of the eruption are interpreted to represent resident, eruptible magmas that did not interact with any magma recharge immediately prior to or during the eruption. We infer that these magmas had been at eruption temperature for some years based on their extensively equilibrated Fe–Ti oxides.