Campbell Plateau
The Campbell Plateau is a large oceanic plateau south of New Zealand and the Chatham Rise. It originated in the Gondwanan breakup and is part of Zealandia, a largely submerged continent. The above sea level parts of the plateau — the Bounty Islands, Antipodes Islands, Auckland Islands and Campbell Island — form part of the New Zealand Subantarctic Islands which were declared a World Heritage Site in 1998. Large parts of the Campbell Plateau lies less than 1000 m below sea level. It rises to 500 m at the Pukaki Rise and emerges above sea level at the Auckland and Campbell Islands.
Covering an area of 800,000 km2 (310,000 sq mi), the Campbell Plateau has a gently undulating bathymetry with major rises trending east-west: Campbell Island Rise, Pukaki Rise, and Bounty Island Ridge. There are two near-parallel rises on the western margin: Stewart Island–Snare Island Rise and Auckland Island platform. The continental slopes are steep on western and southern margins while the northern margin slowly falls into the Bounty Trough.
The Campbell Plateau is a roughly triangular, cratonic microcontinent which formed during the break-up of Gondwana around 80 Ma. Large parts of the plateau are made of Palaeozoic or older granites overlain by much younger shield volcanoes who form the Auckland and Campbell Islands.
The Campbell Plateau is made of continental crust, but, as such, is unusually thin. The reason for this is debated, but there are two likely candidates: either an Early Cretaceous extensional events or the Late Cretaceous break-up between New Zealand and Antarctica. Cretaceous extension between the South Island and the Campbell Plateau created the Great South Basin in which 8 km of sediments have since accumulated. The Bounty Trough was created during the same process. The Campbell Plateau can have been affected by this extension or an earlier event.
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