Okinawa Trough

The Okinawa Trough (沖縄トラフ Okinawa Torafu) (also called Chinese: 中琉界沟, literally China-Ryukyu Border Trough[1] ) is a seabed feature of the East China Sea. It is an active, initial back-arc rifting basin which has formed behind the Ryukyu arc-trench system in the West Pacific. It developed where the Philippine Sea Plate is subducting under the Eurasia Plate.[2]

BAB of the World -Converted-
The Okinawa trough in context of back-arc basins of the world.


It is a back-arc basin formed by extension within the continental lithosphere behind the far deeper Ryukyu Trench-arc system.[3] The thickness of the crust in the northern Okinawa Trough is 30 km, thinning to 10 km in the southern Okinawa Trough.[4] It has a large section more than 1,000 metres (3,300 ft) deep and a maximum depth of 2,716 metres (8,911 ft).

The Okinawa Trough still in an early stage of evolving from arc type to back-arc activity.

Implications for the China–Japan maritime boundary


Okinawa trough topographic
Okinawa trough

The existence of the Okinawa Trough complicates descriptive issues in the East China Sea.[5] According to Professor Ji Guoxing of the Asia-Pacific Department at Shanghai Institute for International Studies,

  • China's interpretation of the geography is that

    "...the Okinawa Trough proves that the continental shelves of China and Japan are not connected, that the Trough serves as the boundary between them, and that the Trough should not be ignored ...."[5]

  • Japan's interpretation of the geography is that

    "...the trough is just an incidental depression in a continuous continental margin between the two countries ... and that any legal effect of the trough should be ignored ...."[5]

Legal Procedure

On August 15, 2013, China's mission did a presentation to the Commission on the Limits of the Continental Shelf[6] (CLCS) established under the United Nations Convention on the Law of the Sea (UNCLOS). The presentation was on the proposal that demarcates the limits of the outer continental shelf beyond 200 nm in part of the East China Sea.[7] China states that China's continental shelf in the East China Sea extends to China-Ryukyu Border Trough naturally, which has been over 200 nautical miles away from the mainland baseline of Chinese territorial waters. According to UNCLOS, any country claiming continental shelves beyond 200 nm shall provide relevant scientific evidence to CLCS. To collect solid data, China deployed 14 scientific survey ships, covering an area of 250,000 square kilometers.[8][9]


  1. ^ "Chronology of Defending Diaoyu Islands". Tsinghua University (Beijing) Library. Retrieved 3 June 2013. 横渡中琉界沟黑水沟,进入"琉球大洋",乃因此沟以东属琉球海域,以西包括钓鱼台列屿乃属中国海域。
  2. ^ Thakur, Naresh Kumar et al. (2010). Exploration of Gas Hydrates: Geophysical Techniques, p. 119., p. 119, at Google Books
  3. ^ Sibuet, Jean-Claude et al. "Back arc extension in the Okinawa Trough," Journal of Geophysical Research, Vol. 92, Issue B13, p. 14041-14063.
  4. ^ Backarc basins : tectonics and magmatism. Taylor, Brian, 1953-. New York. ISBN 9781461518433. OCLC 883383730.CS1 maint: others (link)
  5. ^ a b c Ji, Guoxing. (1995). "Maritime Jurisdiction in the Three China Seas," p. 10. UC Berkeley: UC Institute on Global Conflict and Cooperation; retrieved 15 Nov 2010.
  6. ^ [1]
  7. ^ State Oceanic Administration (August 16, 2013). "China Did a Presentation to CLCS on Demarcating Limits of Over-200-nm Outer Continental Shelf of the East China Sea" (in Chinese). Beijing, China. Missing or empty |url= (help)
  8. ^ State Oceanic Administration (August 16, 2013). "Legally and Scientifically Sound--Discussions about China's Proposal on Demarcating Outer Continental Shelf in the East China Sea" (in Chinese). Beijing, China. Missing or empty |url= (help)
  9. ^ Xinjing Bao (August 16, 2013). "Experts Discusses China's Proposal" (in Chinese). Retrieved August 16, 2013.


  • Taylor, Brian. (1995). Backarc Basins: Tectonics and Magmatism. New York: Plenum Press. ISBN 9780306449376; OCLC 32464941
  • Thakur, Naresh Kumar and Sanjeev Rajput. (2010). Exploration of Gas Hydrates: Geophysical Techniques. Berlin: Springer Verlag. ISBN 9783642142338 ISBN 3642142338; OCLC 646113755
Abyssotrophon soyoae

Abyssotrophon soyoae is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.


Alvinocarididae is a family of shrimp, originally described by M. L. Christoffersen in 1986 from samples collected by DSV Alvin, from which they derive their name. Shrimp of the family Alvinocarididae generally inhabit deep sea hydrothermal vent regions, and hydrocarbon cold seep environments. Carotenoid pigment has been found in their bodies. The family Alvinocarididae comprises 7 extant genera.

Bathyacmaea secunda

Bathyacmaea secunda is a species of very small (adults are typically about 6 mm in length), deep-sea limpet, a marine gastropod mollusk in the family Pectinodontidae. This species inhabits the dark, chemosynthesis-based marine communities of ocean vents and cold seeps near Japan (e.g. the Okinawa Trough).

It is distinct from other true limpets in the following ways, among others: its intestine runs through its ventricle, it has a pair of radular "teeth" with long shafts, and its statocysts are isolated from the pleural ganglia and pedal ganglia. It also has a ctenidium rather than the usual set of circumpallial gills, lacks osphradia, and does not have even rudimentary eyes.

For these reasons, along with a comparison of the development of the shell at the microscopic level, it has been argued that B. secunda is not closely related to the Patelloidea or the Neolepetopsidae as one might expect based on simple morphological characteristics and similarity of appearance. This species has a surprising number of traits in common with the Acmaeidae, however, suggesting a possible close connection with that family rather than the other true limpet families.


Carlsbergite is a nitride mineral that has the chemical formula CrN, or chromium nitride.

It is named after the Carlsberg Foundation which backed the recovery of the Agpalilik fragment of the Cape York meteorite in which the mineral was first described.It occurs in meteorites along the grain boundaries of kamacite or troilite in the form of tiny plates. It occurs associated with kamacite, taenite, daubreelite, troilite and sphalerite.In addition to the Cape York meteorite, carlsbergite has been reported from:

the North Chile meteorite in the Antofagasta Province, Chile

the Nentmannsdorf meteorite of Bahretal, Erzgebirge, Saxony

the Okinawa Trough, Senkaku Islands, Okinawa Prefecture, Japan

the Uwet meteorite of Cross River State, Nigeria

the Sikhote-Alin meteorite, Sikhote-Alin Mountains, Russia

the Hex River Mountains meteorite from the Cape Winelands District, Western Cape Province, South Africa

the Canyon Diablo meteorite of Meteor Crater, Coconino County, Arizona

the Smithonia meteorite of Oglethorpe County, Georgia

the Kenton County meteorite of Kenton County, Kentucky

the Lombard meteorite of Broadwater County, Montana

the Murphy meteorite of Cherokee County and the Lick Creek meteorite of Davidson County, North Carolina

the New Baltimore meteorite of Somerset County, Pennsylvania

Cognatiyoonia sediminum

Cognatiyoonia sediminum is a Gram-negative, strictly aerobic and short rod-shaped bacterium from the genus of Cognatiyoonia which has been isolated from marine sediments from the northern Okinawa Trough in China.

Domibacillus iocasae

Domibacillus iocasae is a Gram-positive bacterium from the genus of Domibacillus which has been isolated from deep sea sediments from the Okinawa Trough.

East China Sea EEZ disputes

There are disputes between China, Japan, and South Korea over the extent of their respective exclusive economic zones (EEZs) in the East China Sea.

The dispute between the People's Republic of China (PRC) and Japan concerns the different application of the 1982 United Nations Convention on the Law of the Sea (UNCLOS), which both nations have ratified. China proposed the application of UNCLOS, considering the natural prolongation of its continental shelf, advocating that the EEZ extends as far as the Okinawa Trough. Its Ministry of Foreign Affairs has stated that "the natural prolongation of the continental shelf of China in the East China Sea extends to the Okinawa Trough and beyond 200 nautical miles from the baselines from which the breadth of the territorial sea of China is measured," which is applicable to the relevant UNCLOS provisions that support China's right to the natural shelf. In 2012, China presented a submission under the UNCLOS concerning the outer limits of the continental shelf to the UN. Japan, based on UNCLOS, proposed the Median line division of the EEZ.

Under the United Nations' Law of the Sea, the PRC claims the disputed ocean territory as its own Exclusive Economic Zone (EEZ) due to its being part of PRC's natural extension of its continental shelf, while Japan claims the disputed ocean territory as its own EEZ because it is within 200 nautical miles (370 km) from Japan's coast, and proposed a median line as the boundary between the EEZ of China and Japan. About 40,000 square kilometres (15,000 square miles) of EEZ are in dispute. China and Japan both claim 200 nautical miles (370 km; 230 mi) of EEZ rights, but the East China Sea width is only 360 nautical miles (670 km; 410 mi). China claims an EEZ extending to the eastern end of the Chinese continental shelf (based on UNCLOS III) which goes deep into the Japanese's claimed EEZ.In 1995, the People's Republic of China (PRC) discovered an undersea natural gas field in the East China Sea, namely the Chunxiao gas field, which lies within the Chinese EEZ while Japan believes it is connected to other possible reserves beyond the median line. Japan has objected to PRC development of natural gas resources in the East China Sea near an area where the two countries Exclusive Economic Zone (EEZ) claims overlap. The specific development in dispute is the PRC's drilling in the Chunxiao gas field, which is located in undisputed areas on China's side, three or four miles (6 km) west of the median line proposed by Japan. Japan maintains that although the Chunxiao gas field rigs are on the PRC side of a median line that Tokyo regards as the two sides' sea boundary, they may tap into a field that stretches underground into the disputed area. Japan therefore seeks a share in the natural gas resources. The gas fields in the Xihu Sag area in the East China Sea (Canxue, Baoyunting, Chunxiao, Duanqiao, Wuyunting, and Tianwaitian) are estimated to hold proven reserves of 364 BCF of natural gas. Commercial operations began 2006. In June 2008, both sides agreed to jointly develop the Chunxiao gas fields.Rounds of disputes about island ownership in the East China Sea have triggered both official and civilian protests between China and Japan.The dispute between PRC and South Korea concerns Socotra Rock, a submerged reef on which South Korea has constructed a scientific research station. While neither country claims the rock as territory, the PRC has objected to Korean activities there as a breach of its EEZ rights.South Korea opened a museum in central Seoul in 2012 to back its claim to the Liancourt Rocks. Visitors can walk around a large 3-D model of the island and examine video and computerized content on the island's history and nature. Video screens show live footage of the island from a fixed camera. In January 2018 the Japanese government opened a small museum in Tokyo displaying maps and documents to defend its territorial claims against neighboring South Korea and China.

Lebetimonas natsushimae

Lebetimonas natsushimae is a moderately thermophilic, strictly anaerobic and chemoautotrophic bacterium from the genus of Lebetimonas which has been isolated from a hydrothermal vent from the Mid-Okinawa Trough.

Masaaki Kimura

Masaaki Kimura (木村 政昭, Kimura Masaaki, born 6 November 1940) is a Professor Emeritus from the Faculty of Science of the University of the Ryukyus, Okinawa, Japan.


Nitratiruptor sp. (strain SB155-2) is a genus of deep sea gram-negative ε-proteobacteria isolated from Iheya North Hydrothermal field in Okinawa Trough (Japan). This rod-shaped microorganism (0.5 x 1.5 µm) grows chemolithoautotrophically in a wide variety of electron donors and acceptors (i.e. sulfur, hydrogen, oxygen and nitrate) in absence of light and oxygen. It is also a thermophilic group capable of growing within the range of 37–65 °C with the optimal at 55 °C.

Okinawa Plate

The Okinawa Plate, or Okinawa Platelet, is a minor continental tectonic plate in the northern and eastern hemispheres stretching from the northern end of Taiwan to the southern tip of the island of Kyūshū. The Okinawa Plate hosts typical earthquakes, like the 1911 Kikai Island earthquake, and various types of slow earthquakes, including low frequency earthquakes, very low frequency earthquakes, tremor, and slow slip events.

Proscyllium venustum

The spotted smooth dogfish (Proscyllium venustum) is a finback catshark of the family Proscylliidae, found in the temperate northwest Pacific Ocean, in the Okinawa Trough. Little else is known about this harmless oviparous species.

Pyrococcus horikoshii

Pyrococcus horikoshii is a hyperthermophilic, anaerobic archaeon, first isolated from hydrothermal fluid samples obtained at the Okinawa Trough vents at a depth of 1,395 metres (4,577 ft). It is obligately heterotrophic, cells are irregular cocci with a tuft of flagella, growing optimally at 98 °C, sulphur greatly enhancing its growth.

Pyropelta ryukyuensis

Pyropelta ryukyuensis is a species of small sea snail, a deep-water limpet, a marine gastropod mollusks in the family Pyropeltidae.

Ryukyu arc

The Ryukyu arc (琉球弧, Ryūkyū-ko) is a volcanic island arc system of Japan's triple junction formed by the subduction of the Philippine Sea Plate beneath the Eurasian Plate between Ryukyu Trench to the south-east and the Okinawa Trough to north-west. It comprises the entirety of the Ryukyu Islands chain. The Ryukyu and Southwest Honshu arcs together form the southwest trending arm of the Boso Triple Junction.


Sulfurovum is a genus within the Epsilonproteobacteria which was first described in 2004 with the isolation and description of the type species Sulfurovum lithotrophicum from Okinawa trough hydrothermal sediments. Named for their ability to oxidize sulfur and their egg-like shape, cells are gram-negative, coccoid to short rods. Mesophilic chemolithoautotrophic growth occurs by oxidation of sulfur compounds coupled to the reduction of nitrate or molecular oxygen.

Sulfurovum lithotrophicum

Sulfurovum lithotrophicum is a species of bacteria, the type species of its genus. It is a sulfur-oxidizing chemolithoautotroph within the ε-Proteobacteria isolated from Okinawa Trough hydrothermal sediments. It is mesophilic and also oxidises thiosulfate. It is a Gram-negative, non-motile and coccoid to oval-shaped bacterium. The type strain is 42BKTT (=ATCC BAA-797T =JCM 12117T).


Thioreductor is a Gram-negative, mesophilic, hydrogen-oxidizing, sulfur-reducing and motile genus of bacteria from the family of unclassified Epsilonproteobacteria with one known species (Thioreductor micantisoli). Thioreductor micantisoli has been isolated from hydrothermal sediments from the Iheya North from the Mid-Okinawa Trough in Japan.

Yangtze Plate

The Yangtze Plate, also called the South China Block or the South China Subplate, comprises the bulk of southern China. It is separated on the east from the Okinawa Plate by a rift that forms the Okinawa Trough which is a back-arc basin, on the south by the Sunda Plate and the Philippine Sea Plate, and on the north and west by the Eurasian Plate. The Longmenshan Fault on the latter border was the site of the 2008 Wenchuan earthquake.The Yangtze Plate was formed by the disaggregation of the Rodinia Supercontinent 750 million years ago, in the Neoproterozoic era. South China rifted away from the Gondwana supercontinent in the Silurian. During the formation of the great supercontinent Pangaea, South China was a smaller, separate continent located off the east coast of the supercontinent and drifting northward. In the Triassic the Yangtze Plate collided with the North China Plate, thereby connecting with Pangaea, and formed the Sichuan basin. In the Cenozoic the Yangtze Plate was influenced by the collision of the Indian and Eurasian plates creating the uplifting of the Longmen Mountains. Its southward motion is accommodated along the Red River fault.

Faults and rift zones
Trenches and troughs


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