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

N. Mortimer, P. B. Gans, S. Meffre, C. E. Martin, M. Seton, S. Williams, R. E. Turnbull, P. G. Quilty, S. Micklethwaite, C. Timm, R. Sutherland, F. Bache, J. Collot, P. Maurizot, P. Rouillard, N. Rollet

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27 Citations (Scopus)

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.

Original languageEnglish
Title of host publicationLarge Igneous Provinces from Gondwana and Adjacent Regions
EditorsS Sensarma, B C Storey
Place of PublicationLondon UK
PublisherGSL Publishing
Pages199-226
Number of pages28
Volume463
Edition1
ISBN (Print)9781786203250
DOIs
Publication statusPublished - 1 Jan 2018

Publication series

NameGeological Society Special Publication
Number1
Volume463
ISSN (Print)0305-8719

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