Neogene sediment structures in Bounty Trough, eastern New Zealand: Influence of magmatic and oceanic current activity

Abstract

New seismic reflection profiles have been interpreted to shed more light on the Neogene deposition in Bounty Trough, an aborted rift characterizing the eastern New Zealand continental margin. Two major processes influencing the deposition were identified. Magmatic activity led to the formation of basement highs, which deform the sedimentary sequences up to early and middle Miocene. The origin of the magmatism unfortunately cannot be solved with the new data presented here. It is difficult to say whether the magmatic activity is an on-going process. Drape structures in the youngest sedimentary unit argue against this. The Oligocene–Miocene represents a period of major change. Bottom current activity then took over as the most important depositional process. Strong cooling events in the late Miocene resulted in modification in the oceanographic regime east of New Zealand. This led to the formation of channels, sediment drifts, and sediment waves. At least since the Miocene, bottom current activity has been the dominating depositional process.