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

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posted on 2023-05-24, 04:57 authored by Mortimer, N, Gans, PB, Sebastien MeffreSebastien Meffre, Martin, CE, Seton, M, Williams, S, Turnbull, RE, Quilty, PG, Micklethwaite, S, Timm, C, Sutherland, R, Bache, F, Collot, J, Maurizot, P, Rouillanr, P, Rollet, N
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.

History

Publication title

Large Igneous Provinces from Gondwana and Adjacent Regions

Volume

463

Editors

S Sensarma, BC Storey

Pagination

199-226

ISBN

978-1-78620-320-5

Department/School

School of Natural Sciences

Publisher

The Geological Society

Place of publication

London

Extent

15

Rights statement

Copyright 2017 The Authors

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences

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