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Progressive mixed-magma recharging of Izu-Oshima volcano, Japan: A guide to magma chamber volume

Progressive mixed-magma recharging of Izu-Oshima volcano, Japan: A guide to magma chamber volume
Progressive mixed-magma recharging of Izu-Oshima volcano, Japan: A guide to magma chamber volume
To discover how magmas move and interact beneath an arc we have examined the temporal and spatial evolution of the largest Izu-Bonin frontal arc volcano Izu-Oshima and the adjacent Izu-Tobu field of backarc volcanoes. Extensive 14C ages and geochemical analysis of subaerial satellite cones as well as other effusives has enabled us to construct a well-constrained ?14 ka?14 ka record of Izu-Oshima volcanism.

The geochemistry of Izu-Oshima is found to change systematically through the last 14?000 yr. Ba/La, Pb/Ce, 87Sr/86Sr, 143Nd/144Nd and 206Pb/204Pb all decrease between 10 ka and 5 ka before increasing between 5 ka and the present, while La/Yb and Nb/Zr show the reverse. These changes in composition match the addition of Izu-Tobu (backarc) magma to the Izu-Oshima plumbing system with a maximum of a 40% Izu-Tobu at around 5 ka. Progressive but asymptotically declining changes in composition through the 10–5 ka period are found to fit a model where pre-mixed magma is episodically added to, and mixed with, a chamber beneath Izu-Oshima. The 5–0 ka period reverses this trend, but is again progressive and declining, suggesting a switch to a progressive influx of pure Izu-Oshima frontal arc magma. Combining flux and eruption volume estimates with the observed geochemical mixing rates indicates that the accessible melt volume of the Izu-Oshima magma system is ?16 km3?16 km3. Interaction and pre-mixing between the fluid-dominated frontal arc melt and the sediment-bearing backarc magmas must occur at deeper levels within the arc crust. This deep reservoir receives a continuous feed from the frontal arc mantle, but may periodically intercept rising magmas from the backarc source to produce episodes of magma mixing on timescales of ?5000 yr?5000 yr.

This study demonstrates that interaction between frontal arc and backarc magma needs to be considered to achieve better understanding of material transfers and elemental budgets at subduction zones.
arc volcano, temporal variation, geochemistry, 14C ages, Izu-Oshima, magma chamber volume
0012-821X
19-29
Ishizuka, Osamu
1fb98a88-bff7-4200-a09d-92ddf1616058
Taylor, Rex N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Geshi, Nobuo
0974d7ec-3252-41ca-b2b7-ba9c5c2a2067
Oikawa, Teruki
1d32c548-0dc6-42a4-9d3c-4446fdb1dd2c
Kawanabe, Yoshihisa
176559a2-8852-48af-ae0d-0c2f95e506e6
Ogitsu, Itaru
b9435704-c312-46f8-af9d-65b662e7415d
Ishizuka, Osamu
1fb98a88-bff7-4200-a09d-92ddf1616058
Taylor, Rex N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Geshi, Nobuo
0974d7ec-3252-41ca-b2b7-ba9c5c2a2067
Oikawa, Teruki
1d32c548-0dc6-42a4-9d3c-4446fdb1dd2c
Kawanabe, Yoshihisa
176559a2-8852-48af-ae0d-0c2f95e506e6
Ogitsu, Itaru
b9435704-c312-46f8-af9d-65b662e7415d

Ishizuka, Osamu, Taylor, Rex N., Geshi, Nobuo, Oikawa, Teruki, Kawanabe, Yoshihisa and Ogitsu, Itaru (2015) Progressive mixed-magma recharging of Izu-Oshima volcano, Japan: A guide to magma chamber volume. Earth and Planetary Science Letters, 430, 19-29. (doi:10.1016/j.epsl.2015.08.004).

Record type: Article

Abstract

To discover how magmas move and interact beneath an arc we have examined the temporal and spatial evolution of the largest Izu-Bonin frontal arc volcano Izu-Oshima and the adjacent Izu-Tobu field of backarc volcanoes. Extensive 14C ages and geochemical analysis of subaerial satellite cones as well as other effusives has enabled us to construct a well-constrained ?14 ka?14 ka record of Izu-Oshima volcanism.

The geochemistry of Izu-Oshima is found to change systematically through the last 14?000 yr. Ba/La, Pb/Ce, 87Sr/86Sr, 143Nd/144Nd and 206Pb/204Pb all decrease between 10 ka and 5 ka before increasing between 5 ka and the present, while La/Yb and Nb/Zr show the reverse. These changes in composition match the addition of Izu-Tobu (backarc) magma to the Izu-Oshima plumbing system with a maximum of a 40% Izu-Tobu at around 5 ka. Progressive but asymptotically declining changes in composition through the 10–5 ka period are found to fit a model where pre-mixed magma is episodically added to, and mixed with, a chamber beneath Izu-Oshima. The 5–0 ka period reverses this trend, but is again progressive and declining, suggesting a switch to a progressive influx of pure Izu-Oshima frontal arc magma. Combining flux and eruption volume estimates with the observed geochemical mixing rates indicates that the accessible melt volume of the Izu-Oshima magma system is ?16 km3?16 km3. Interaction and pre-mixing between the fluid-dominated frontal arc melt and the sediment-bearing backarc magmas must occur at deeper levels within the arc crust. This deep reservoir receives a continuous feed from the frontal arc mantle, but may periodically intercept rising magmas from the backarc source to produce episodes of magma mixing on timescales of ?5000 yr?5000 yr.

This study demonstrates that interaction between frontal arc and backarc magma needs to be considered to achieve better understanding of material transfers and elemental budgets at subduction zones.

Full text not available from this repository.

More information

Published date: 15 November 2015
Keywords: arc volcano, temporal variation, geochemistry, 14C ages, Izu-Oshima, magma chamber volume
Organisations: Geochemistry

Identifiers

Local EPrints ID: 383158
URI: http://eprints.soton.ac.uk/id/eprint/383158
ISSN: 0012-821X
PURE UUID: 580632ed-efc8-4be9-a7e6-34367f286452

Catalogue record

Date deposited: 21 Oct 2015 14:38
Last modified: 15 Jul 2019 21:00

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