Regional volcanism of northern Zealandia: post-Gondwana break-up magmatism on an extended, submerged continent

Type Article
Date 2018-02
Language English
Author(s) Mortimer N.1, Gans P. B.2, Meffre S.3, Martin C. E.4, Seton M.5, Williams S.5, Turnbull R. E.1, Quilty P. G.3, Micklethwaite S.6, Timm C.7, Sutherland R.8, Bache Francois9, Collot Julien10, Maurizot P.10, Rouillard P.10, Rollet N.11
Affiliation(s) 1 : GNS Science, Dunedin, New Zealand
2 : Department of Earth Science, University of California, Santa Barbara, USA
3 : Department of Earth Sciences, University of Tasmania, Hobart, Australia
4 : Department of Geology, University of Otago, Dunedin, New Zealand
5 : School of Geosciences, University of Sydney, Australia
6 : School of Earth, Atmosphere and Environment, Monash University, Melbourne, Australia
7 : GNS Science, Lower Hutt, New Zealand
8 : School of Geography, Environment and Earth Sciences, Victoria University of Wellington, New Zealand
9 : Santos Ltd., Adelaide, Australia
10 : Service Geologique de Nouvelle Calédonie, Nouméa, New Caledonia
11 : Geoscience Australia, Canberra, Australia
Source Geological Society, London, Special Publications (0305-8719) (Geological Society of London), 2018-02 , Vol. 463 , N. 1 , P. 199-226
DOI 10.1144/SP463.9
Note Geological Society, London, Special Publications. Volume 463, 2018 Large Igneous Provinces from Gondwana and Adjacent Regions. Edited by: S. Sensarma, University of Lucknow, India and B. C. Storey, University of Canterbury, New Zealand
Abstract

Volcanism of Late Cretaceous–Miocene age is more widespread across the Zealandia continent than previously recognized. New age and geochemical information from widely spaced northern Zealandia seafloor samples can be related to three volcanotectonic regimes: (1) age-progressive, hotspot-style, low-K, alkali-basalt-dominated volcanism in the Lord Howe Seamount Chain. The northern end of the chain (c. 28 Ma) is spatially and temporally linked to the 40–28 Ma South Rennell Trough spreading centre. (2) Subalkaline, intermediate to silicic, medium-K to shoshonitic lavas of >78–42 Ma age within and near to the New Caledonia Basin. These lavas indicate that the basin and the adjacent Fairway Ridge are underlain by continental rather than oceanic crust, and are a record of Late Cretaceous–Eocene intracontinental rifting or, in some cases, speculatively subduction. (3) Spatially scattered, non-hotspot, alkali basalts of 30–18 Ma age from Loyalty Ridge, Lord Howe Rise, Aotea Basin and Reinga Basin. These lavas are part of a more extensive suite of Zealandia-wide, 97–0 Ma intraplate volcanics. Ages of northern Zealandia alkali basalts confirm that a late Cenozoic pulse of intraplate volcanism erupted across both northern and southern Zealandia. Collectively, the three groups of volcanic rocks emphasize the important role of magmatism in the geology of northern Zealandia, both during and after Gondwana break-up. There is no compelling evidence in our dataset for Late Cretaceous–Paleocene subduction beneath northern Zealandia.

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Mortimer N., Gans P. B., Meffre S., Martin C. E., Seton M., Williams S., Turnbull R. E., Quilty P. G., Micklethwaite S., Timm C., Sutherland R., Bache Francois, Collot Julien, Maurizot P., Rouillard P., Rollet N. (2018). Regional volcanism of northern Zealandia: post-Gondwana break-up magmatism on an extended, submerged continent. Geological Society, London, Special Publications, 463(1), 199-226. Publisher's official version : https://doi.org/10.1144/SP463.9 , Open Access version : https://archimer.ifremer.fr/doc/00439/55100/