Abstract:
The Chatham Rise is a marine plateau in the New Zealand region formed by the fragmentation of the Gondwana continental margin in the mid- to Late Cretaceous. It comprises a wide zone of buried, fault-angle half-grabens that possibly developed above a detachment extending under the Bounty Trough rift. Clastic sedimentation took place in basin-and-range, rift basins oriented parallel with the strike of the rise. Regional erosion and post-rift thermal subsidence towards the end of the Cretaceous and in the early Paleogene resulted in a gradual marine transgression up the flanks of the Bounty Trough and over the rise and the formation of a regional unconformity. Maastrichtian shallow marine and lagoonal sedimentation culminated in the late Paleogene with deposition of glauconites and bathyal platform limestones on the rise. Regional stability, slow deposition and erosion characterise the Neogene history of the rise crest. The development of a transpressive plate boundary and uplift of the Southern Alps in the late Neogene, brought a new phase of downwarp to the western end of the Chatham Rise and renewed, rapid, clastic sedimentation.