New Zealand Geology

New Zealand is renowned for its diverse geology and dynamic tectonic setting astride an active segment of the boundary between the Pacific and Australian plates. New Zealand is an emergent fraction (5%) of the largely submerged 'continent' of Zealandia which is half the size of Australia. Zealandia is comprised mainly of continental crust but because it is less than 30 km thick, it is largely below sea level. Zealandia's origins relate to eastern Gondwanaland from which it rifted during the Late Cretaceous to early Cenozoic, with formation of the Tasman Sea floor. Continental Zealandia may be thought of as part of the Australian/Gondwanaland mineral estate, and it is rich in natural resources. However, it was stretched and thinned for 100 Myr, culminating in the Eocene with development of the modern plate boundary. New Zealand largely owes its emergence to plate collision processes within the past 25 Myr.