The University of Southampton
University of Southampton Institutional Repository

Late quaternary tephra layers around Raoul and Macauley islands, Kermadec arc: implications for volcanic sources, explosive volcanism and tephrochronology

Shane, Phil and Wright, Ian C. (2011) Late quaternary tephra layers around Raoul and Macauley islands, Kermadec arc: implications for volcanic sources, explosive volcanism and tephrochronology Journal of Quaternary Science, 26, (4), pp. 422-432. (doi:10.1002/(ISSN)1099-1417).

Record type: Article

Abstract

A suite of deep-sea cores were collected along transects up to 100?km across the fore-arc and back-arc regions of the predominantly submarine Kermadec arc near Raoul and Macauley islands, southwest Pacific. The cores reveal a macroscopic tephra record extending back >50?ka. This is a significant addition to the dated record of volcanism, previously restricted to fragmented late Holocene records exposed on the two islands. The 27 macroscopic tephra layers display a wide compositional diversity in glass (?50–78?wt% SiO2). Many tephra layers comprise silicic shards with a subordinate mafic shard population. This could arise from magma mingling and may reflect mafic triggering of the silicic eruptions. Broadly, the glass compositions can be distinguished on diverging high-K and low-K trends, most likely arising from different source volcanoes. This distinction is also reflected in the tephra records exposed on Raoul (low-K) and Macauley (high-K) islands, the likely source areas. Heterogeneous tephra comprising shards of both high- and low-K affinity, silicic and mafic compositions, and more homogeneous tephra with subordinate outlier shard compositions, are best explained by post-depositional mixing of separate eruption deposits or contemporaneous eruptions. Evidently, the slow sedimentation rates of the calcareous oozes (?101–102?mm?ka?1) were insufficient to adequately separate and preserve closely spaced eruption deposits. This exemplifies the difficulty in assessing eruption frequencies and magmatic trends, and erecting a tephrostratigraphy, using geochemical fingerprinting in such environments. Despite these difficulties, the ca. 5.7?ka Sandy Bay Tephra erupted from Macauley Island can be correlated over a distance of >100?km, extending east and west of the island, showing that the mostly submerged volcanoes are capable of wide tephra dispersal. Hence there is potential for developing chronostratigraphies for the southwest Pacific beyond the region covered by the extensive rhyolite marker beds from the Taupo Volcanic Zone.

Full text not available from this repository.

More information

Published date: May 2011
Keywords: Kermadec, tephra, geochemistry, deep sea, glass chemistry
Organisations: Marine Geoscience

Identifiers

Local EPrints ID: 186601
URI: http://eprints.soton.ac.uk/id/eprint/186601
ISSN: 0267-8179
PURE UUID: a78bd079-4b9f-45d5-9db3-973a209556f9

Catalogue record

Date deposited: 13 May 2011 13:21
Last modified: 18 Jul 2017 11:47

Export record

Altmetrics

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.

×