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Geochemical and isotopic insights into the assembly, evolution and disruption of a magmatic plumbing system before and after a cataclysmic caldera-collapse eruption at Ischia volcano (Italy)

Brown, R.J.; Civetta, L.; Arienzo, I.; D'Antonio, M.; Moretti, R.; Orsi, G.; Tomlinson, E.L.; Albert, P.G.; Menzies, M.A.

Geochemical and isotopic insights into the assembly, evolution and disruption of a magmatic plumbing system before and after a cataclysmic caldera-collapse eruption at Ischia volcano (Italy) Thumbnail


Authors

L. Civetta

I. Arienzo

M. D'Antonio

R. Moretti

G. Orsi

E.L. Tomlinson

P.G. Albert

M.A. Menzies



Abstract

New geochemical and isotopic data on volcanic rocks spanning the period ~75–50 ka BP on Ischia volcano, Italy, shed light on the evolution of the magmatic system before and after the catastrophic, caldera-forming Monte Epomeo Green Tuff (MEGT) eruption. Volcanic activity during this period was influenced by a large, composite and differentiating magmatic system, replenished several times with isotopically distinct magmas of deep provenance. Chemical and isotopic variations highlight that the pre-MEGT eruptions were fed by trachytic/phonolitic magmas from an isotopically zoned reservoir that were poorly enriched in radiogenic Sr and became progressively less radiogenic with time. Just prior to the MEGT eruption, the magmatic system was recharged by an isotopically distinct magma, relatively more enriched in radiogenic Sr with respect to the previously erupted magmas. This second magma initially fed several SubPlinian explosive eruptions and later supplied the climactic, phonolitic-to-trachytic MEGT eruption(s). Isotopic data, together with erupted volume estimations obtained for MEGT eruption(s), indicate that >5–10 km3 of this relatively enriched magma had accumulated in the Ischia plumbing system. Geochemical modelling indicates that it accumulated at shallow depths (4–6 km), over a period of ca. 20 ka. After the MEGT eruption, volcanic activity was fed by a new batch of less differentiated (trachyte-latite) magma that was slightly less enriched in radiogenic Sr. The geochemical and Sr–Nd-isotopic variations through time reflect the upward flux of isotopically distinct magma batches, variably contaminated by Hercynian crust at 8–12 km depth. The deep-sourced latitic to trachytic magmas stalled at shallow depths (4–6 km depth), differentiated to phonolite through crystal fractionation and assimilation of a feldspar-rich mush, or ascended directly to the surface and erupted.

Citation

Brown, R., Civetta, L., Arienzo, I., D'Antonio, M., Moretti, R., Orsi, G., …Menzies, M. (2014). Geochemical and isotopic insights into the assembly, evolution and disruption of a magmatic plumbing system before and after a cataclysmic caldera-collapse eruption at Ischia volcano (Italy). Contributions to Mineralogy and Petrology, 168(3), Article 1035. https://doi.org/10.1007/s00410-014-1035-1

Journal Article Type Article
Acceptance Date Jun 19, 2014
Online Publication Date Aug 19, 2014
Publication Date Sep 1, 2014
Deposit Date Oct 1, 2014
Publicly Available Date Mar 28, 2024
Journal Contributions to Mineralogy and Petrology
Print ISSN 0010-7999
Electronic ISSN 1432-0967
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 168
Issue 3
Article Number 1035
DOI https://doi.org/10.1007/s00410-014-1035-1
Keywords Ischia volcano, Magmatic plumbing system, Radiogenic isotopes, Geothermometry, Feldspar assimilation, Caldera collapse.

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