Paleogeography of the Taranaki Basin region during the latest Eocene–Early Miocene and implications for the ‘total drowning’ of Zealandia

Abstract

Latest Eocene–earliest Miocene strata in the subsurface of the Taranaki Basin provide important new regional paleogeographic and tectonic constraints not available from outcrop. Six paleogeographic maps of the Taranaki Basin region have been produced utilising extensive well, seismic reflection and outcrop data. These record three broad periods of sedimentation characterised by (1) variable transgression and initial deformation (c. 40–30 Ma); (2) maximum transgression with moderate deformation (c. 30–21 Ma); and (3) regression with accelerated deformation (< 21 Ma). Local sedimentation patterns were influenced by reverse faulting, producing depocentres and topographic highs adjacent to the Taranaki Fault System. Reverse faulting commenced as early as c. 40 Ma and may signify the onset of subduction beneath the North Island. In common with other parts of New Zealand, the region reached maximum marine inundation in the Waitakian (c. 23 Ma). However, the deposition of thick clastic sediments in eastern parts of Taranaki Basin, coupled with ongoing tectonism, suggests the presence of land throughout the Oligocene and Early Miocene, and is inconsistent with total Oligocene drowning of Zealandia.