Tectonic Controls on Cenozoic Sedimentation in the North Island New Zealand

Abstract

Cenozoic deformation of the North Island was dominated by the “closure” of the Challenger Rift and the establishment of the presently active subduction system. The initiation of subduction-related volcanic chains and their subsequent migration influenced the source of clastic material deposited in the Neogene basins. Uplift patterns, shoreline and drainage configurations were governed by complex 3-D distortion of the transition between the Alpine Fault system in the south and the Hikurangi through subduction system in the north. Along the Pacific side of the island, in Northland, some “piggy back” basins were formed on allochthonous pockets of sediments involved in obduction of ocean floor rocks onto the North island. Clockwise rotation on the east coast region and alternate coupling and decoupling across the subduction thrust created short-lived forearc basins. Axial ranges, and derivation of gravels from them are younger than 1 m y B.P. A very young, still active cross structure due to oblique subduction led to the formation of South Taranaki Bight, caused differences in the width of the axial ranges along their length and may be the reason for the peculiar coastal indentation of Hawke Bay.