"Centroid depths and mechanisms of mid-ocean ridge earthquakes in the Indian Ocean. Gulf of Aden, and Red Sea""

The strait of Bab al-Mandeb, “the gate of tears” or “the gate of the wailing yard”, joins the high seas of the Gulf of Aden and the Indian Ocean to those of the Red Sea. The name is primarily used by geographers to designate the narrowest part of the passage, between Ras Bab al-Mandeb on the Asian shore and Ras Siyan in Africa. At this point it is bordered on the east by the Yemen Arab Republic (Northern Yemen) and the People's Democratic Republic of Yemen (Southern Yemen), and in the west by the Republic of Djibouti (formerly the French Territory of the Afars and Issas). About 14 miles farther north, where the Red Sea (or, for that matter, the strait) is nearly 20 miles wide, lies the coast of Ethiopia (the province of Eritrea). All the riparians claim a territorial sea of 12 miles, and the Yemen Arab Republic, as well as the People's Democratic Republic of Yemen, also claim jurisdiction for certain purposes in an additional zone of 6 miles.On the eastern shore of the strait of Bab al-Mandeb lies the peninsula of Ras Bab al-Mandeb, which is about 6–10 km. wide. It consists of rocky, volcanic plains with several hills of 200–300 m. The coast of Ras Bab al-Mandeb is surrounded by coral reefs of a width of up to 1500 m. The border between North Yemen and South Yemen passes down the middle of Ras Bab al-Mandeb.

Download Full-text

Marine Reservoir Correction for the Cocos (Keeling) Islands, Indian Ocean

Radiocarbon ◽

10.1017/s0033822200035645 ◽

2004 ◽

Vol 46 (2) ◽

pp. 603-610 ◽

Cited By ~ 13

Author(s):

Quan Hua ◽

Colin D Woodroffe ◽

Mike Barbetti ◽

Scott G Smithers ◽

Ugo Zoppi ◽

...

Keyword(s):

Mass Spectrometry ◽

Indian Ocean ◽

Red Sea ◽

Surface Waters ◽

Accelerator Mass Spectrometry ◽

Arabian Sea ◽

Indonesian Throughflow ◽

Gulf Of Aden ◽

The Indian Ocean ◽

Reservoir Age

Known-age corals from the Cocos (Keeling) Islands, Indian Ocean, have been analyzed by accelerator mass spectrometry (AMS) for radiocarbon to determine marine reservoir age corrections. The ΔR value for the Cocos (Keeling) Islands is 66 ± 12 yr based on the analyses undertaken for this study. When our AMS and previously published dates for Cocos are averaged, they yield a ΔR of 64 ± 15 yr. This is a significant revision of an earlier estimate of the ΔR value for the Cocos (Keeling) Islands of 186 ± 66 yr (Toggweiler et al. 1991). The (revised) lower ΔR for the Cocos (Keeling) Islands is consistent with GEOSECS 14C data for the Indian Ocean, and previously published bomb 14C data for the Red Sea, Gulf of Aden, and Cocos Islands. The revised ΔR is also close to values for the eastern Indian Ocean and adjacent seas. These suggest surface waters that reach the Cocos Islands might be partly derived from the far western Pacific, via the Indonesian throughflow, and might not be influenced by the southeast flow from the Arabian Sea.

Download Full-text

Marine Shell Working at Harlaa, Ethiopia, and the Implications for Red Sea Trade

Journal of African Archaeology ◽

10.1163/21915784-20210001 ◽

2021 ◽

pp. 1-24

Author(s):

Timothy Insoll

Keyword(s):

Indian Ocean ◽

Red Sea ◽

North Africa ◽

Persian Gulf ◽

Arabian Peninsula ◽

Gulf Of Aden ◽

Horn Of Africa ◽

Eastern Ethiopia ◽

The Indian Ocean ◽

Marine Shell

Abstract Twelve species of marine shell were transported in significant quantities from the Red Sea to the trade centre of Harlaa in eastern Ethiopia between the eleventh and early fifteenth centuries AD. Initially, it was thought that species such as the cowries were imported from the Indian Ocean. Subsequent research has found that all were available from the Red Sea and the Gulf of Aden, c. 120 km east of Harlaa. This suggests that a hitherto largely unrecognised source of marine shells was available, and the Red Sea might have supplied not only the Horn of Africa, but other markets, potentially including Egypt, and from there, elsewhere in North Africa and ultimately West Africa via trans-Saharan routes, as well as Nubia and further south on the Nile in the Sudan, the Arabian Peninsula, and the Arabian/Persian Gulf. This is explored with reference to the shell assemblage from Harlaa, and selected shell assemblages from elsewhere in the Horn of Africa, and trading centres on the Red Sea.

Download Full-text

Seafloor topography and tectonic elements of the Western Indian Ocean

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2004.1472 ◽

2005 ◽

Vol 363 (1826) ◽

pp. 15-24 ◽

Cited By ~ 10

Author(s):

Lindsay M. Parson ◽

Alan J. Evans

Keyword(s):

Indian Ocean ◽

Plate Boundary ◽

Western Indian Ocean ◽

Ocean Basin ◽

Seafloor Topography ◽

Sedimentary Sequences ◽

Mid Ocean Ridge ◽

The Face ◽

The Indian Ocean ◽

Ocean Ridge

The break–up of Gondwanaland and dispersal of several of its component continental fragments, which eventually formed the margins of the Indian Ocean, have produced an ocean basin of enormous variety, both in relief and in origin of seafloor features. The western half of the Indian Ocean alone contains every type of tectonic plate boundary, both active and fossil, and, along with some of the deepest fracture zones, the most complex mid–ocean ridge configurations and some of the thickest sedimentary sequences in the world's ocean basins. This ocean is one of the most diverse on the face of the globe. We explore the evolution of the morphology of the Indian Ocean floor, and discuss the effect of its variations, maxima and minima, on the interconnectivity of the ocean's water masses.

Download Full-text

Convection tectonics: some possible effects upon the Earth's surface of flow from the deep mantle

Canadian Journal of Earth Sciences ◽

10.1139/e88-117 ◽

1988 ◽

Vol 25 (8) ◽

pp. 1199-1208 ◽

Cited By ~ 17

Author(s):

J. Tuzo Wilson

Keyword(s):

Land Surface ◽

Angle Of Incidence ◽

Gulf Of Aden ◽

Upward Flow ◽

New Techniques ◽

Ocean Ridges ◽

The Earth ◽

Mid Ocean Ridge ◽

The Subject ◽

Ocean Ridge

Until a little more than a century ago the land surface not only was the only part of the Earth accessible to humans but also was the only part for which geophysical and geochemical methods could then provide any details. Since then scientists have developed ways to study the ocean floors and some details of the interior of the Earth to ever greater depths. These discoveries have followed one another more and more rapidly, and now results have been obtained from all depths of the Earth.New methods have not contradicted or greatly disturbed either old methods or old results. Hence, it has been easy to overlook the great importance of these recent findings.Within about the last 5 years the new techniques have mapped the pattern of convection currents in the mantle and shown that these rise from great depths to the surface. Even though the results are still incomplete and are the subject of debate, enough is known to show that the convection currents take two quite different modes. One of these breaks the strong lithosphere; the other moves surface fragments and plates about.It is pointed out that if expanding mid-ocean ridges move continents and plates, geometrical considerations demand that the expanding ridges must themselves migrate. Hence, collisions between ridges and plates are likely to have occurred often during geological time.Twenty years ago it was shown that the effect of a "mid-ocean ridge in the mouth of the Gulf of Aden" was to enter and rift the continent. This paper points out some of the conditions under which such collisions occur and in particular shows that the angle of incidence between a ridge and a coastline has important consequences upon the result. Several past and present cases are used to illustrate that collisions at right angles tend to produce rifting; collisions at oblique angles appear to terminate in the lithosphere in coastal shears, creating displaced terrane, but in the mantle the upward flow may continue to uplift the lithosphere far inland and produce important surface effects; collisions between coasts and mid-ocean ridges parallel to them produce hot uplifts moving inland. For a time these upwellings push thrusts and folds ahead of them, but they appear to die down before reaching cratons.

Download Full-text