Abstract

The Taranaki Basin, situated offshore western New Zealand, is one of several large sedimentary basins formed during the Late Cretaceous in response to break-up of the palaeo-Pacific margin of Gondwana. A review of published structural, stratigraphic and geochronological data indicates that NE to NNE striking basement faults, generated during Palaeozoic to Mesozoic terrane accretion along the Gondwana margin, have strongly influenced the development of the basin. The main basin-bounding faults, the Cape Egmont Fault Zone and the Taranaki Fault, correspond to the boundaries of a narrow belt of plutonic rocks known as the Median Tectonic Zone. Geological data from onshore South Island suggests that right-lateral movement occurred along the boundaries of the Median Tectonic Zone during the Early Cretaceous. From the Late Cretaceous to Early Tertiary, NE to NNE striking normal faults within the Taranaki Basin controlled deposition in a series of en-echelon half-grabens and sub-basins. Many of the normal faults were later reactivated during a phase of compressional deformation associated with the development of the Australian-Pacific plate boundary through New Zealand. Reverse movement on the Taranaki Fault began in the early Miocene and deformation propagated westward reaching the Cape Egmont Fault Zone in the late Miocene to early Pliocene.

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