A tectonic reconstruction model for Aotearoa-New Zealand from the mid-Late Cretaceous to the present day

Abstract

ABSTRACT We present a mid-Late Cretaceous to present day tectonic reconstruction model for Aotearoa-New Zealand. Our GPlates model comprises 50 rigid crustal blocks grouped into regions with common deformation histories set within a well-defined Australia-Pacific-Antarctica plate circuit tied to a published global paleomagnetic absolute reference frame. Within the model, four distinct periods of deformation are recognised from both near- and far-field observations. A key model assumption is the continuity of basement terranes between North and South Zealandia prior to Middle Eocene rifting and Late Oligocene initiation of transform motion. To complement the rigid crustal block model, continuously closing polygons show a ∼25% decrease in plate boundary area since the Middle Eocene that has been compensated for by corresponding increases in crustal thickness. A kinematic fault-propagation fold model demonstrates the plausibility of post-Late Oligocene asymmetric oroclinal folding on both sides of the evolving transform boundary. ‘Missing’ areas of map section common to previous tectonic reconstructions can be reconciled through contraction, elongation and vertical-axis rotation of continental crust within the deformation zone ahead of northward propagation of the Alpine Fault. This tectonic reconstruction model provides an open, accessible, and testable foundation for current and future paleogeographic and tectonic studies across Zealandia.