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26-792: In some usages, the name Owen Transform Fault is used to denote the short section between the end of the Aden-Sheba ridge and the Carlsberg Ridge. Additionally, this area has been called the Aden–Owen–Carlsberg triple junction , although the Carlsberg Ridge is offset 330 km (210 mi) from the point where the Owen Fracture Zone/fault intersects the Sheba segment of the Aden Ridge. The Owen Fracture Zone

52-766: A general reorganisation of continental plates in the Indian Ocean in response to the Arabia-Eurasia collision. Aden%E2%80%93Owen%E2%80%93Carlsberg triple junction The Aden–Owen–Carlsberg triple junction ( AOC ), also known as the Arabia–India–Somalia triple junction , is a triple junction that connects the Aden Ridge , Owen Fracture Zone , and Carlsberg Ridge in the northwest Indian Ocean . It has been described as one of only three RRF (ridge–ridge–fault) triple junctions on Earth, besides

78-409: A lack of large-scale commercial fishing facilities, the coastline supports many isolated fishing towns and villages. The Gulf of Aden is richly supplied with fish, turtles, and lobsters. Local fishing takes place close to the shore; sardines, tuna, kingfish, and mackerel make up the bulk of the annual catches. Crayfish and sharks are also fished locally. In antiquity , the ancient Greeks viewed what

104-642: A rate of 200 km (120 mi)/Ma. The Owen Fracture Zone, together with the Dalrymple Trough in its northern end, is a transform fault along which spreading between the Arabian and Indian plates at the Carlsberg Ridge becomes the subduction of the Himalayan orogeny . The Owen Fracture Zone passes east of the Owen Ridge which was uplifted during the opening of the eastern Gulf of Aden in

130-603: A rise in piracy in the area. The 1st-century Periplus of the Erythraean Sea documents one Egyptian captain's experiences during this era. After the collapse of the Roman economy, direct trade ceased but the Awsan I port Crater , located just south of the modern city of Aden, remained an important regional center. In late antiquity and the early medieval period, there were several invasions of Yemen from Ethiopia ; after

156-561: A second 39 to 23 Ma ultra-slow (0.6 cm/year (0.24 in/year)) stage during the India-Eurasia collision; followed by the present slow (1.2 cm/year (0.47 in/year)) spreading which reaches 2.2 ± 0.1 cm/year (0.866 ± 0.039 in/year) in its northern end. This latest stage was initiated by the opening of the Gulf of Aden during which the Aden Ridge began to quickly propagate westward at

182-458: A warship escort in the area. A geologically young body of water, the Gulf of Aden has a unique biodiversity that includes many varieties of fish , coral , seabirds and invertebrates . This rich ecological diversity has benefited from a relative lack of pollution by humans in the past. However, environmental groups fear that the lack of a coordinated effort to control pollution may jeopardize

208-667: Is a near-linear structure that drops steeply 2,000 m (6,600 ft) on its eastern side. The top layers of the Southern Ridge are formed by the Oligocene-Early Miocene turbidites of the Indus River Fan and later cover. The Central Owen ridge, 220 km (140 mi)-long and 50 km (31 mi)-wide, in contrast, is more uneven and reaches a maximum height of 1,700 m (5,600 ft). The Qalhat Seamount and Murray Ridge are located at

234-772: Is a vital waterway for shipping, especially for Persian Gulf oil , making it an integral waterway in the world economy . Approximately 11% of the world's seaborne petroleum passes through the Gulf of Aden on its way to the Suez Canal or to regional refineries. The main ports along the gulf are Aden , Balhaf , Bir Ali , Mukalla , and Shokra in Yemen ; Djibouti City in Djibouti ; Zeila in Somaliland , Berbera in Somaliland , and Bosaso in Somalia . In antiquity ,

260-585: Is extremely slow. Analysing the Aden–Owen–Carlsberg triple junction, however, geologists have been able to determine that before 11 Ma the Nubia–Somalia relative motion was faster than today and contained a significant strike-slip component. Gulf of Aden The Gulf of Aden ( Arabic : خليج عدن ; Somali : Gacanka Cadmeed ) is a deepwater gulf of the Indian Ocean between Yemen to

286-663: Is named after HMS Owen that identified the 'fracture line' in April/May 1963. The Owen fracture Zone and the Dalrymple Trough north of it (named after HMS Dalrymple surveyed the area together with HMS Owen ) form the modern boundary between the Arabian and Indian plates. 800 km (500 mi)-long, the Owen Fracture Zone runs along the Owen Ridge which is divided into two. The Southern Owen Ridge, 300 km (190 mi) long and 50 km (31 mi)-wide,

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312-528: Is now called the Gulf of Aden as an extension of the Erythraean Sea (Red Sea) ‹See Tfd› Greek : Ἐρυθρὰ Θάλασσα , Erythrà Thálassa . They named several of the islands in the gulf, including one they called Stratonis, although it is no longer clear which Greek name referred to which island. In Abu'l-Fida 's A Sketch of the Countries ( Arabic : تقويم البلدان ), the present-day Gulf of Aden

338-464: Is often used for the delivery of Persian Gulf oil , making the gulf an integral waterway in the world economy . Important cities along the Gulf of Aden include the namesake Aden in Yemen . Other Yemeni cities are Zinjibar , Shuqrah , Ahwar , Balhaf , Mukalla , Ash-Shihr , al-Hami , Hadibu , and Qulensya . On the African side are the cities of Djibouti , Berbera and Bosaso . Despite

364-515: The Azores triple junction and Chile triple junction . However, because the fault arm of such unstable triple junctions tend to evolve into a spreading centre, all three cases have quickly evolved into stable RRR triple junctions. Since a reorganisation of the involved tectonic plates c. 10 Ma , the AOC moves in discrete steps westward along the Aden Ridge. West of the southern termination of

390-682: The Early Miocene. North of the Aden-Owen-Carlsberg Triple Junction the Owen Fracture Zone is quiet for 250 km (160 mi) but right-lateral slip along its active segments indicates that Arabia is moving northward faster than India. The relative motion between the Nubian and Somalian plates before 3.2 Ma is difficult to determine since the movement in the Southwest Indian Ridge

416-593: The Gulf. The importance of the Gulf of Aden declined while the Suez Canal was closed, but it was revitalized when the canal was reopened in 1975, after being deepened and widened by the Egyptian government . The waterway is part of the important Suez Canal shipping route between the Mediterranean Sea and the Arabian Sea in the Indian Ocean, with 21,000 ships crossing the gulf annually. This route

442-542: The Late Cretaceous and the accretionary wedge there developed 7.2 to 11.6 Ma . Seismic lines from drillings in the 1970s and 1980s beneath both ridges revealed a structure now known as the 50 to 55 Ma -old Proto-Owen Ridge which was uplifted and rejuvenated during the Early Miocene. According to one reconstruction, before the initiation of the Carlsberg Ridge the Arabian–Indian boundary

468-665: The Owen fracture Zone, the Beautemps-Beaupré Basin, a new plate boundary develops and the basin will be transferred from the Arabian plate to the Indian plate in a near future. The Carlsberg Ridge was opened between the Seychelles and India in the early Tertiary and has since undergone three stages of spreading. A first, fast stage 61 to 51 Ma with a 6 cm/year (2.4 in/year) half-rate spreading;

494-483: The gulf was a thriving area of international trade between Ptolemaic Egypt and Rome in the west and Classical India , its Indonesian colonies , and Han China in the east. It was not limited to transshipment , as Yemeni incense , tortoiseshell , and other goods were in high demand in both directions. After Egyptian sailors discovered the monsoon winds and began to trade directly with India, caravan routes and their associated kingdoms began to collapse, leading to

520-508: The limits of the Gulf of Aden as follows: The temperature of the Gulf of Aden varies between 15 °C (59 °F) and 28 °C (82 °F), depending on the season and the monsoons . The salinity of the gulf at 10 metres (33 ft) depth varies from 35.3 ‰ along the eastern Somali coast to as high as 37.3 ‰ in the gulf's center, while its oxygen content at the same depth is typically between 4.0 and 5.0 mg/L. Exclusive economic zones in Gulf of Aden: The Gulf of Aden

546-406: The middle of the gulf, and tectonic activity at the ridge is causing the gulf to widen by about 15 mm (0.59 in) per year. The ancient Greeks regarded the gulf as one of the most important parts of the " Erythraean Sea ". It later came to be dominated by Muslims, as the area around the gulf converted to Islam . From the late 1960s onwards, there was an increased Soviet naval presence in

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572-662: The north, the Arabian Sea to the east, Djibouti to the west, and the Guardafui Channel , the Socotra Archipelago , Puntland in Somalia and Somaliland to the south. In the northwest, it connects with the Red Sea through the Bab-el-Mandeb strait, and it connects with the Arabian Sea to the east. To the west, it narrows into the Gulf of Tadjoura in Djibouti . The Aden Ridge lies along

598-710: The northern end of the Owen Fracture Zone. The exchange of deep water from the Somali Basin to the Arabian Basin through the OFZ has been estimated to 2  Sv . In the Arabian Basin the current splits into a northern and southern branch that both flow parallel to the Carlsberg Ridge. Seafloor spreading in the Sheba ridge began c. 20 Ma . Subduction in the Makran Trench was initiated in

624-565: The rise of Islam, the gulf permitted repeated migrations of northwest Africa by Arab settlers. In the first decade of the 2000s, especially during the war in Somalia , the gulf evolved into a hub of pirate activity. By 2013, attacks in the waters had steadily declined due to private security and international navy patrols. India receives US$ 50 billion in imports – and sends US$ 60 billion in exports – through this area annually. To protect its trade and that of other countries, India keeps

650-565: Was called the Gulf of Berbera, which shows how important Berbera was in both regional and international trade during the medieval period. Legendary navigator Ibn Majid also referred to the Gulf of Aden as the Gulf of Berbera in his 15th century magnum opus The Book of the Benefits of the Principles and Foundations of Seamanship . Berbera has been a prominent port since antiquity. The International Hydrographic Organization defines

676-524: Was located off Oman 90 to 60 Ma while the Mascarene Basin opened between Madagascar and the Seychelles. In the Early Miocene ( c. 20 Ma ) the boundary jumped to its present location which uplifted the Owen Ridge. 10–12 km (6.2–7.5 mi)-long offsets along the OFZ indicate a 3-6 Ma-old dextral strike-slip motion but this motion can be extended to 20 Ma based on magnetic anomaly reconstructions. This coincides with

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