The geochemistry and petrogenesis of Carnley Volcano, Auckland Islands, SW Pacific

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Date
2018-09-19
Authors
Gamble, John A.
Adams, Chris J.
Morris, Paul A.
Wysoczanski, Richard J.
Handler, Monica
Timm, Christian
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Taylor & Francis Group, LLC
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Abstract
Intraplate volcanism across Zealandia, South Eastern Australia, the Ross Sea Embayment and Marie Byrd Land in Antarctica define a magmatic province characterised by basalts with elevated 206Pb/204Pb (18.9–22.5), 87Sr/86Sr = ∼0.7035, Light Rare Earth enrichment [(Ce/Yb)n > 10], and convex-up mantle normalised incompatible multi-element patterns, peaking at Nb-Ta, with negative K and Pb anomalies. Trace element abundances and ratios (e.g. Zr/Nb, Y/Zr) resemble Ocean Island Basalts (OIB), distinct from Mid-Ocean Ridge Basalt (MORB), suggesting derivation from OIB-like reservoirs. Our preferred scenario envisages partial melting across the garnet-spinel stability fields involving asthenospheric and lithospheric mantle components. Melts accumulate in a column where the deep (asthenospheric) source is PM and the shallower source a melange of PM and subcontinental lithospheric mantle (DMM+1) enriched by carbonatite. Evolution of primary and near-primary magmas is controlled by olivine + clinopyroxene fractionation. Trachybasalts, trachytes and rhyolites show isotopic evidence for interaction with continental crust.
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Keywords
Intra-plate volcanism , Auckland Islands , Zealandia , SW Pacific , Magma petrogenesis
Citation
Gamble, J. A., Adams, C. J., Morris, P. A., Wysoczanski, R. J., Handler, M. and Timm, C. (2018) 'The geochemistry and petrogenesis of Carnley Volcano, Auckland Islands, SW Pacific', New Zealand Journal of Geology and Geophysics, 61(4), pp. 480-497. doi:10.1080/00288306.2018.1505642
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© 2018, Informa UK Limited, trading as Taylor & Francis Group. This is an Accepted Manuscript of an article published by Taylor & Francis in New Zealand Journal of Geology and Geophysics on 19 September, 2018, available online: http://www.tandfonline.com/10.1080/00288306.2018.1505642