The Bounty Trough began as a Cretaceous failed rift within submerged continental crust, east of New Zealand. Up to Oligocene times, the 350 km x 1000 km trough was starved of terrigenous sediment and received mainly biopelagic material. This changed with the onset of mountain building related to development of the Pacific-Australian plate boundary in the Miocene. Terrigenous input commenced and increased, with the increasing tempo of the orogeny which continues today. However, the principal control of terrigenous supply to the trough was glacio-eustatic fluctuations of sea level. During times of low sea level rivers draining the rising mountain ranges extended eastwards across the emergent continental shelf and discharged directly into the trough. Part of the sediment load contributed towards shelf progradation whereas detritus escaping this depocentre either was spread as a hemipelagic blanket or was transported along the floor of the Bounty Trough by turbidity currents constrained within the 950+ km long Bounty Channel. These flows overspilled the channel to produce extensive levees whereas those completing the journey fed the abyssal Bounty Fan on the floor of the S.W. Pacific Basin. The main phase of fan growth began in the late Pliocene concomitant with the onset of glacio-eustatic lowerings of sea level. These bouts of high sediment influx were punctuated by times of pervasive biopelagic deposition coinciding with interglacial periods. Under conditions of raised sea level, a reduced terrigenous supply was diverted from the Bounty Trough by the onset of an effective along-shelf transport regime.

West: 174.5652 East: 174.5653 North: -45.3129 South: -46.3128

Expedition: 90

Site: 90-594

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=1994-045664 (c.f. for more detailed metadata)

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