The Kermadec Trench is a linear

ocean trench Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic t ...

in the south

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

. It stretches about from the

Louisville Seamount Chain The Louisville Ridge, often now referred to as the Louisville Seamount Chain, is an underwater chain of over 70 seamounts located in the Southwest portion of the Pacific Ocean. One of the longest seamount chains on Earth, it stretches some Vander ...

in the north (26°S) to the

Hikurangi Plateau The Hikurangi Plateau is an oceanic plateau in the South Pacific Ocean east of the North Island of New Zealand. It is part of a large igneous province (LIP) together with Manihiki and Ontong Java, now located and north of Hikurangi respect ...

in the south (37°S), north-east of

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

North Island The North Island ( , 'the fish of Māui', historically New Ulster) is one of the two main islands of New Zealand, islands of New Zealand, separated from the larger but less populous South Island by Cook Strait. With an area of , it is the List ...

. Together with the

Tonga Trench The Tonga Trench is an oceanic trench located in the southwestern Pacific Ocean. It is the deepest trench in the Southern hemisphere and the second deepest on Earth after the Mariana Trench. The fastest plate-tectonic velocity on Earth is occurri ...

to the north, it forms the -long, near-linear Kermadec-Tonga subduction system, which began to evolve in the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

when the Pacific plate started to subduct beneath the

Australian plate The Australian plate is or was a major tectonic plate in the eastern and, largely, southern hemispheres. Originally a part of the ancient continent of Gondwana, Australia remained connected to India and Antarctica until approximately when Indi ...

Convergence Convergence may refer to: Arts and media Literature *''Convergence'' (book series), edited by Ruth Nanda Anshen *Convergence (comics), "Convergence" (comics), two separate story lines published by DC Comics: **A four-part crossover storyline that ...

rates along this subduction system are among the fastest on Earth, /yr in the north and /yr in the south.

Geology

The Kermadec Trench is one of Earth's deepest oceanic trenches, reaching a depth of . Formed by the subduction of the Pacific plate under the Indo-Australian plate, it runs parallel with and to the east of the Kermadec Ridge and

island arc Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have re ...

. The

marks the continuation of subduction to the north. The Kermadec Trench has a southern continuation in the

turbidite A turbidite is the geologic Deposition (geology), deposit of a turbidity current, which is a type of amalgamation of fluidal and sediment gravity flow responsible for distributing vast amounts of clastic sediment into the deep ocean. Sequencing ...

-filled Hikurangi Trough, but a series of seamounts on the Australian plate act as a dam and prevents this turbidity from reaching the sediment-starved Kermadec Trench. Debris from a larger subducted seamount probably dammed the trench from 2 Ma to 0.5 Ma and similar events probably redirected sediments in similar ways before that. Two oceanic plates meet at the Kermadec Trench which is located far from any larger landmass. Because of this, the Pacific plate as well as the trench itself is only covered by of sediments. The trench is almost perfectly straight and its simple geometry is the result of the uniformity of the subducting sea-floor. This sea-floor formed at the extinct Osbourn Trough, located just north of the

. Abyssal hills on the subducting sea-floor are oriented perpendicular to the old spreading centre and the sea-floor is 72–80 Ma near the Louisville seamounts at the northern end and more than 100 Ma near Hikurangi Plateau at the southern end. There are no seamounts on the sea-floor near the Kermadec Trench except one sitting on the trench slope at which has been dated to 54.8±1.9 Ma. The Hikurangi Plateau formed part of the Ontong-Java-

Manihiki 250px, Map of Manihiki Atoll Manihiki is an atoll in the northern group of the Cook Islands known informally as the "Island of Pearls". It is located in the Northern Cook Island chain, approximately north of the capital island of Rarotonga, ...

- Hikurangi

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive ( sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The format ...

(LIP) during the Ontong Java Event 120 . The Manihiki Plateau is currently subducting under the southern part of the Kermadec Arc but most of it has already been subducted. The LIP-arc collision occurred north of its present location, but oblique plate convergence has migrated the subducted plateau southward.

Fauna

In 2012, deep sea researchers discovered individuals of a species of giant amphipod at the trench's lowest depths. Unlike most amphipods, which are approximately 2.5 cm (1 inch) long, this species reaches up to 34 cm (13 inches) in length, and is milky-white. The second-deepest fish, the

hadal The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around below sea level, and exists in long, narrow, topographic V-shaped depressions. The cumula ...

snailfish '' Notoliparis kermadecensis'', is endemic to the trench and occupies a very limited depth range, . A species of pearlfish, '' Echiodon neotes'', has been caught in the Kermadec Trench at a depth of . All other known pearlfishes live in the range and the presence of ''E. neotes'' at this depth remains unexplained.

Exploration

In May 2014, the ''Nereus'', an unmanned research submarine operated by the

Woods Hole Oceanographic Institution The Woods Hole Oceanographic Institution (WHOI, acronym pronounced ) is a private, nonprofit research and higher education facility dedicated to the study of marine science and engineering. Established in 1930 in Woods Hole, Massachusetts, it i ...

(WHOI), imploded due to high pressure at a depth of 9,990 metres while exploring the Kermadec Trench. In December 2022, a research team from the

Chinese Academy of Sciences The Chinese Academy of Sciences (CAS; ) is the national academy for natural sciences and the highest consultancy for science and technology of the People's Republic of China. It is the world's largest research organization, with 106 research i ...

and National Institute of Water and Atmospheric Research reached the bottom of the Scholl Deep nearly 10 km below the surface.

References

Notes Bibliography * * * * * *

External links

* An animation of a 3D model of the Kermadec Trench {{Coord, 31, S, 177, W, region:XP_dim:1000000, display=title Zealandia Geography of the Kermadec Islands Geography of the New Zealand seabed Oceanic trenches of the Pacific Ocean Subduction zones

Geology

Fauna

Exploration

See also

References

External links