New Zealand Journal of Geology and Geophysics abstracts
Cretaceous to early Tertiary basaltic volcanism in the Far North of New
Zealand: geochemical associations and their tectonic significance
K. N. Nicholson
Department of Geology
Ball State University
Muncie, IN 47306, USA
email: knichols@bsu.edu
P. M. Black*
Department of Geology
University of Auckland
Private Bag 92 019
Auckland, New Zealand
*Author for correspondence.
Abstract Geochemical data for the Cretaceous to early
Tertiary basaltic volcanics of northernmost New Zealand reveal there is clear
chemical distinction between the basalts of the Houhora Complex and Tangihua
Complex. The Tangihua Complex volcanics have both arc and backarc signatures,
and a younger set of intrusions cutting the Tangihua pillow lava complexes
have calc-alkaline affinities. The Houhora Complex lavas have chemical similarities
with the younger Tangihua intrusives but the geochemical signature of the
Houhora Complex basalts indicates generation in a well-established arc system
with continental affinities. Other basic lava complexes in the Far North
have compositions that differ from both the Tangihua and the Houhora Complexes.
A late set of dikes, found particularly in the Three Kings Islands, can be
distinguished geochemically from both the older volcanics and the younger
late Miocene arc volcanism. A new model is proposed to explain the variety
of chemistry and the presence of a continental signature in many of the Cretaceous
lavas of northernmost New Zealand. Our model invokes, in addition, the stalled
subduction and capture of the Phoenix plate and a long period of quiescence
between generation and emplacement of the ophiolite.
Keywords Cretaceous; volcanism; Tangihua Complex volcanics;
Mt Camel Terrane; Houhora Complex; Three Kings Islands; Northland
G03050; Received 22 May 2003; accepted 26 September 2003; Online publication
date 7 September 2004
New Zealand Journal of Geology & Geophysics, 2004, Vol. 47: 437-446
0028-8306/04/4703-0437 © The Royal Society of New Zealand 2004
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