15°30′N 155°0′E / 15.500°N 155.000°EPako Guyot is a guyot in the Pacific Ocean.
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Name
The guyot is also known as Caiwei[1] or Pallada after the Russian frigate Pallada.[2]
Geomorphology
Pako Guyot reaches a depth of 1,350 metres (4,430 ft).[3] It has dimensions of 40 by 65 kilometres (25 mi × 40 mi) and features a summit plateau 2,056 square kilometres (794 sq mi) wide[4] at a depth of 1,500–1,650 metres (4,920–5,410 ft)[3] with a shape corresponding to an irregular rectangle-triangle.[2] With an area of 13,680 square kilometres (5,280 sq mi), Pako Guyot is the third-largest guyot on Earth, only behind Koko Seamount and Suiko Seamount.[5] The summit plateau is covered by sediments 25–100 metres (82–328 ft) thick[6] including foraminiferal ooze, while the flanks feature small-scale features such as depressions, ridges and trenches.[3] Former reefs occur on the seamount[7] and during the Cretaceous and Eocene left mudstones and limestones on the seamount. Later, pelagic limestones were emplaced on them. A 65 square kilometres (25 sq mi) large area on the northwestern corner of Pako Guyot's summit plateau is free of sediments.[6]
Geology
The guyot is part of the Magellan Seamounts.[8] The seamount was volcanically active during the Cretaceous-Paleogene[9] 91.3 million years ago[10] and may have formed on a hotspot together with Ioah Guyot and Vlinder Guyot;[11] a late phase of volcanism may have taken place in the Paleocene-Eocene.[12] The hotspots that formed Pako Guyot were located in what is today French Polynesia.[6]
Volcanic rocks dredged from Pako are of sodium-potassium hawaiitic and trachybasaltic composition[2] and geochemically resemble these erupted by the Rarotonga hotspot.[13] Clays with Cenomanian-age radiolarian fossils cover the entire lower slopes of Pako Guyot.[7]
Biota
Corals and squat lobsters have been found on the seamount.[14] Ophiuroids, most of which are symbiotic with corals and sponges, live on the seamount and its flanks.[1] Diverse communities including brittle stars, corals, fish, sea anemones, sea cucumbers, sea lilies, sea urchins, shrimp and starfish have been found at its feet, where organic matter accumulates.[3] Ammonites lived on the seamount during the Cretaceous.[15]
Mining
The seamount features substantial deposits of ferromanganese and phosphorite ores.[2] In 2014, China obtained a contract with the International Seabed Authority allowing for exploration of Pako Guyot for cobalt crusts.[16]