The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Using high-resolution Pb isotopes to unravel the petrogenesis of Sakurajima Volcano, Japan

Using high-resolution Pb isotopes to unravel the petrogenesis of Sakurajima Volcano, Japan
Using high-resolution Pb isotopes to unravel the petrogenesis of Sakurajima Volcano, Japan
Sakurajima volcano on the rim of Aira caldera erupts daily, threatening the major nearby population centre of Kagoshima. Before 1955, eruptions have typically consisted of intermittent plinian and effusive activity, but since 1955 frequent vulcanian explosions have occurred, indicating a change in pre-eruptive processes. High resolution Pb isotopes are used here to constrain the components, including crustal assimilants, and petrogenetic processes contributing to the composition of both pre and post 1955 magmas. Sakurajima eruptive products have more radiogenic Pb (206Pb/204Pb = 18.40-18.42) than nearby Sumiyoshiike basalts (206Pb/204Pb = 18.24); a proxy for the primitive magma feeding the Sakurajima-Aira system. Sakurajima samples lie along a mixing line between these basalts and locally exposed crustal compositions. Their Pb isotopes are consistent with addition of ~5 % average crustal melt to the primitive basaltic magma. The narrow range of Pb isotope ratios, despite variable SiO2 contents (56.6 – 72.3 wt %), suggests that the final erupted magmas are derived from fractional crystallization of a mafic precursory magma displaying relatively consistent levels of crustal contamination. Andesites erupted between 4-3.7 ka and the 1995 eruption are contaminated to a greater extent, indicating that magmas with distinct compositions can feed phases of activity or individual eruptions. Post 1955 andesitic pyroclastics have lower SiO2 and higher MgO than older lavas, yet equivalent Pb isotope ratios. The more mafic composition of post 1955 eruptive products can be attributed to increased throughput of
mafic magma to the system.
Crustal contamination, High-resolution Pb isotopes, Ryukyu arc, Sakurajima, Temporal magmatic evolution
0258-8900
Brown, Joshua
4d07e789-2901-47de-b1c5-eac1c5441f58
Taylor, Rex N
094be7fd-ef61-4acd-a795-7daba2bc6183
Masato, iguchi
408ce216-9113-4f03-9fe3-b4bc1898a58a
Brown, Joshua
4d07e789-2901-47de-b1c5-eac1c5441f58
Taylor, Rex N
094be7fd-ef61-4acd-a795-7daba2bc6183
Masato, iguchi
408ce216-9113-4f03-9fe3-b4bc1898a58a

Brown, Joshua, Taylor, Rex N and Masato, iguchi (2020) Using high-resolution Pb isotopes to unravel the petrogenesis of Sakurajima Volcano, Japan. Bulletin of Volcanology, 82 (5), [36]. (doi:10.1007/s00445-020-1371-0).

Record type: Article

Abstract

Sakurajima volcano on the rim of Aira caldera erupts daily, threatening the major nearby population centre of Kagoshima. Before 1955, eruptions have typically consisted of intermittent plinian and effusive activity, but since 1955 frequent vulcanian explosions have occurred, indicating a change in pre-eruptive processes. High resolution Pb isotopes are used here to constrain the components, including crustal assimilants, and petrogenetic processes contributing to the composition of both pre and post 1955 magmas. Sakurajima eruptive products have more radiogenic Pb (206Pb/204Pb = 18.40-18.42) than nearby Sumiyoshiike basalts (206Pb/204Pb = 18.24); a proxy for the primitive magma feeding the Sakurajima-Aira system. Sakurajima samples lie along a mixing line between these basalts and locally exposed crustal compositions. Their Pb isotopes are consistent with addition of ~5 % average crustal melt to the primitive basaltic magma. The narrow range of Pb isotope ratios, despite variable SiO2 contents (56.6 – 72.3 wt %), suggests that the final erupted magmas are derived from fractional crystallization of a mafic precursory magma displaying relatively consistent levels of crustal contamination. Andesites erupted between 4-3.7 ka and the 1995 eruption are contaminated to a greater extent, indicating that magmas with distinct compositions can feed phases of activity or individual eruptions. Post 1955 andesitic pyroclastics have lower SiO2 and higher MgO than older lavas, yet equivalent Pb isotope ratios. The more mafic composition of post 1955 eruptive products can be attributed to increased throughput of
mafic magma to the system.

Text
BUVO-D-19-00108_R2 (5) - Accepted Manuscript
Download (4MB)

More information

Accepted/In Press date: 26 February 2020
e-pub ahead of print date: 4 April 2020
Keywords: Crustal contamination, High-resolution Pb isotopes, Ryukyu arc, Sakurajima, Temporal magmatic evolution

Identifiers

Local EPrints ID: 438630
URI: http://eprints.soton.ac.uk/id/eprint/438630
ISSN: 0258-8900
PURE UUID: b463384a-4683-4dbe-816e-f90b5a3dd6bf

Catalogue record

Date deposited: 19 Mar 2020 17:30
Last modified: 22 Nov 2021 08:04

Export record

Altmetrics

Contributors

Author: Joshua Brown
Author: Rex N Taylor
Author: iguchi Masato

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×