Two-phase Cretaceous–Paleocene rifting in the Taranaki Basin region, New Zealand; implications for Gondwana break-up

The break-up of Gondwana resulted in extension of New Zealand continental crust during the Cretaceous– Paleocene. Offshore the geometry and rift history are well imaged by new regional mapping of a large seismic reflection dataset, tied to wells, used here to document the Cretaceous–Paleocene (c. 105 – 55 Ma) evolution of the greater Taranaki Basin region. Two temporally distinct phases of rifting have been recognized in the region, and record Gondwana break-up. The first (Zealandia rift phase) produced half-grabens trending NW to WNW during the mid-Cretaceous (c. 105 – 83 Ma). These rift basins predate, and are parallel to, Tasman Sea spreading centres. They record distributed stretching of northern Zealandia prior to the onset of seafloor spreading in the Tasman Sea. A short period (c. 83 – 80 Ma) of uplift and erosion followed, possibly representing a break-up unconformity, with erosion in southern Taranaki Basin and deposition of the 'Taranaki Delta' sequence in Deepwater Taranaki. The second, West Coast–Taranaki rift phase produced north- to NE-trending extensional half-grabens in the shelfal Taranaki Basin during the latest Cretaceous–Paleocene (c. 80–55 Ma). This rift was narrow (>150 km wide), orthogonal to Zealandia phase rifting, affected mainly western Zealandia and did not progress to full break-up.