Cretaceous to present-day tectonic reconstructions of Zealandia

Abstract

Reconstructions of the past relative positions of northern and southern Zealandia provide important constraints on the orientation and amount of strain accumulated between rigid plates within the Australia–Pacific plate tectonic circuit. This configuration of plates ultimately determines how, where and when sedimentary basins formed during and since continental breakup along the eastern margin of Gondwana. Although the first-order geometry of Zealandia is well established, uncertainty remains regarding plate motions through the latest Cretaceous to Eocene. Recent reconstructions are, in some cases, inconsistent with geological observations at key time intervals, highlighting uncertainties inherent in plate reconstructions for the south-west Pacific. Building on previous tectonic reconstructions and incorporating published seafloor magnetic interpretations, paleomagnetic observations and geological constraints (e.g. terrane geometry and distribution), we developed a tectonic framework to reconstruct Zealandia back through to the latest Cretaceous. Using GPlates, we use a simple double-hinge slat concept to describe Neogene deformation within the New Zealand plate boundary zone, while the geometry of northern and southern Zealandia during the Eocene is modified from recently published models based on geologic considerations. This study ultimately highlights the need for integrated studies of the Zealandia plate circuit.