Artículos de revistas
Old magma and a new, intrusive trigger: using diffusion chronometry to understand the rapid-onset Calbuco eruption, April 2015 (Southern Chile)
Fecha
2019Registro en:
Contributions to Mineralogy and Petrology, Volumen 174, Issue 7, 2019,
00107999
10.1007/s00410-019-1596-0
Autor
Morgado, Eduardo
Morgan, Daniel J.
Castruccio, Angelo
Ebmeier, Susanna K.
Parada, Miguel Ángel
Brahm Scott, Raimundo
Harvey, Jason
Gutiérrez, Francisco
Walshaw, Richard
Institución
Resumen
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.