The Bounty Trough is a major submerged feature, a bathymetric depression, of the oceanography of the southwest

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

. It is located off the east coast of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

. It is named after the

Bounty Islands The Bounty Islands ( mi, Moutere Hauriri; "Island of angry wind") are a small group of 13 uninhabited granite islets and numerous rocks, with a combined area of , in the South Pacific Ocean. Territorially part of New Zealand, they lie about e ...

near the Eastern end of the trough. The islands, in turn, are named after .

Extent

The Bounty

Trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

is located to the South of the Chatham Rise, and North of the Campbell Plateau. It runs East-West for a distance of some to the deep ocean between the

Chatham Chatham may refer to: Places and jurisdictions Canada * Chatham Islands (British Columbia) * Chatham Sound, British Columbia * Chatham, New Brunswick, a former town, now a neighbourhood of Miramichi * Chatham (electoral district), New Brunswic ...

and

Bounty Bounty or bounties commonly refers to: * Bounty (reward), an amount of money or other reward offered by an organization for a specific task done with a person or thing Bounty or bounties may also refer to: Geography * Bounty, Saskatchewan, a g ...

Island groups. The Bounty Trough's western extremity is less than off the South Island's coast.Marine Gazetteer Placedetails
, ''Marine Regions'' Retrieved 10 December 2016. It covers an area of approximately .David G. Roberts, A.W. Bally. Regional Geology and Tectonics: Phanerozoic Passive Margins, Cratonic Basins and Global Tectonic Maps, Elsevier, 2012, p517. Much of The Bounty Trough lies at depths of , and it marks an indentation in the "coastline" of the largely submerged continent of

Zealandia Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., ...

Geology

A curious feature of the Bounty Trough is that it marks the continuation of several main river features in the South Island – the "Otago Fan Complex".Carter, L., Carter, R.M. and Davy B. Seismic stratigraphy of the Bounty Trough, south-west Pacific Ocean. Elsevier. Marine and Petroleum Geology, Vol 11, Issue 1. 1994. P79-93. This is a distinct series of channels existing in the base of the trough which is an extension of the Clutha and

Waitaki River The Waitaki River is a large braided river that drains the Mackenzie Basin and runs some south-east to enter the Pacific Ocean between Timaru and Oamaru on the east coast of the South Island of New Zealand. It starts at the confluence of the � ...

systems. Both these rivers, especially the Clutha, are noted for their fast flow. This alone would not account for the existence of the channels, though much of their current contours was probably shaped by sediment during the ice ages.Sea Floor Geology
, ''Te Ara Encyclopedia of New Zealand.'' Retrieved 10 December 2014. The channel system is the remnant of a

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

(failed) rift formed via ocean-floor spreading at the time when Zealandia separated from AntarcticaCarter, L., and Carter, R.M., (1987)
The Bounty channel system: A 55-million-year-old sediment conduit to the deep sea, Southwest Pacific Ocean
, ''Geo-Marine Letters'', 7, ''4'', 183–190. between 130 and 85

Mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...

. The channels provide a major transportation system for sediments from the major rivers in the eastern South Island. At the Eastern end of the rift is the abyssal Bounty Fan. In July 2012, the

NIWA The National Institute of Water and Atmospheric Research or NIWA ( mi, Taihoro Nukurangi), is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts research across a broad range of disciplines in the environmental scienc ...

research ship mapped the area finding a structure of nine canyons ending in "a large deep apron-shaped sediment deposit in the Bounty Trough". The survey considered development of a biodiversity assessment of the area which would then support "potential environmental effects of any oil drilling, and help establish environmental guidelines specific to the area".Stuff.co.nz Science
, ''First map shows canyons, creatures and maybe oil.'' Retrieved 10 December 2016. The mapping also found "pock marks" some deep by in diameter in the margins which may indicate methane seepage. The survey could support petrochemical exploration, though, Roberts et al. found evidence of "an extensive and effective petroleum system" to be "conjectural". Both the Otago and abyssal fans, and the rift itself developed from the Kaikoura Orogeny and were greatly accelerated after about 2.5 Ma, with the onset of global glacial/interglacial climatic cycles and the development of an icecap along the alpine region of South Island. The glacial periods contributed large amounts of sediment to the trough. Sediment is not being deposited now in the same way as it was during the glacial period.

References

{{Oceanic features of Zealandia, state=collapsed Geography of the New Zealand seabed Zealandia