[2][5] There are, nevertheless, traces in seamounts on Hikurangi of a second Late Cretaceous magmatic event contemporaneous with volcanism on New Zealand and associated with the final break-up of Gondwana.

The Hikurangi Plateau has been partly subducted under the Chatham Rise, probably during the Cretaceous, and probably resulting in a slab more than 150 km (93 mi) long.

The western margin of the plateau is actively subducting under the North Island of New Zealand to a depth of 65 km (40 mi).

[6] The extent of the Hikurangi Plateau slab suggests that it has played a significant role in the geology of New Zealand during the past 100 Ma.

The Southern Alps in central South Island are being uplifted along the plate boundary there, a fault zone which parallels the western edge of the slab of the Hikurangi Plateau.