A Review of Cretaceous-Cenozoic Sedimentation and Tectonics, East Coast, South Island, New Zealand

Abstract The Canterbury region, in the eastern central part of the South Island of New Zealand, is a mid-Cretaceous to Tertiary depositional centre in which predominantly clastic sediments accumulated. Carbonates were extensive in the Eocene and Oligocene, and volcanics in the mid-Cretaceous and Paleocene to Miocene. Facies distributions from the mid-Cretaceous to Recent show a close relationship with the evolving tectonic regime. There are many similarities with, and some departures from the worldwide, eustatic, sea-level curve for the Cretaceous-Cenozoic. An unconformity near the end of the Early Oligocene is particularly extensive in the region and appears to correlate with the eustatic sea-level fall at 30 Ma. Subsidence and sedimentation rates show similar trends, and are related to the tectonics. They all show maxima in the Cretaceous and from the mid-Tertiary to Recent. This is consistent with plate tectonics models for the breakup of eastern Gondwanaland in the Cretaceous, Tertiary convergence between the Indian-Australian and Pacific plates, strike-slip movement on the Alpine Fault from the mid-Tertiary, and oblique-slip movement on the Alpine Fault in the late Tertiary.