A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Magnetic and gravity fields over the Red Sea

1970 ◽  
Vol 267 (1181) ◽  
pp. 153-180 ◽  
Keyword(s):  
Red Sea ◽  
Gravity Anomalies ◽  
Gulf Of Aqaba ◽  
Second Phase ◽  
Gulf Of Aden ◽  
Horn Of Africa ◽  
Transform Faults ◽  
Gravity Fields ◽  
Anomaly Pattern ◽  
Separate Block

Strong magnetic anomalies associated with the axial trough of the Red Sea are considered to be related to a second phase of opening. Lack of magnetic expression of the first and wider separation is attributed to initial thinning and necking of the continental crust and, possibly, to a slow rate of spreading. The rise of the mantle during this first stage is reflected in the positive Bouguer gravity anomaly which extends over the whole Sea. A displacement of the magnetic anomaly pattern and a grouping of earthquake epicentres at latitude 19½° N delineates a transform fault. Futher offsets in the anomaly pattern between 19½° N and 23° N may be related to other transform faults presently inactive. If Sinai is treated as a separate block then the two-stage clockwise rotation of Africa to open the Red Sea leads to the southerly displacements of this block required by the geology. Negative gravity anomalies in the Gulf of Aqaba support the idea of a shear. A separate rotation of the Horn of Africa is believed to have contributed to the opening of the Gulf of Aden.

Prospects for the Gulf of Aden and Red Sea in 2018-22

2017 ◽  
Keyword(s):  
Red Sea ◽  
Global Financial Crisis ◽  
Gulf Of Aden ◽  
Horn Of Africa ◽  
Content Type ◽  
Security Issues ◽  
Cultural Exchanges ◽  
Gulf States ◽  
The Global Financial Crisis ◽  
Trade And Investment

Subject Prospects for the Gulf of Aden and Red Sea in 2018-22. Significance Rooted in centuries of common history and cultural exchanges, links between the Gulf states and the Horn of Africa have intensified in the decade since the global financial crisis of 2008-09, creating new dynamics across the Gulf of Aden. In the years ahead, deepening trade and investment in agriculture, livestock and infrastructure -- in particular -- are likely to underpin an ever-more-complex web of political and military relationships, with fracturing lines of alliance and enmity shaped by security issues.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The existence of transform faults in the Red Sea depression

1970 ◽  
Vol 267 (1181) ◽  
pp. 407-408 ◽  
Keyword(s):  
Red Sea ◽  
Gulf Of Aden ◽  
Transform Fault ◽  
Basement Complex ◽  
Transform Faults ◽  
Left Handed ◽  
The World ◽  
History Of ◽  
First Motion ◽  
Earthquake Mechanism

Girdler (1968, pp. 1102-1105) has suggested that transform faults may exist in the Red Sea depression. A possible left-handed transform fault, trending at 050°, and centred on 19°N 39°E was plotted (Girdler 1968, fig. 1). This is supposed to offset the axial trough, and run on to the land, where it is shown displacing the ‘marginal structure lines’ and the Mesozoic and Tertiary sedimentary/Basement Complex contact by about 50 km. Girdler (1968) cites Sykes (in History of the Earth's crust , Nasa, Symposium) as providing sup­porting first motion evidence of transform movement along this proposed fault. However Isaacs, Sykes & Oliver (1968, fig. 5) show a left-handed transform ‘earthquake mechanism’ bearing 020° for a centre associated with the axial trough at 17°N, 40° 30' E. Because of the proximity of these centres, the 30° difference in trend, and the scarcity of Red Sea earthquake data, the question arises are Girdler and Isaacs et al . dealing with the same centres ? More data and an explanation are required as there are few places in the world where undisputed trans­form faults have been described from the land and sea. Girdler’s proposed transform fault is therefore extremely important both from a local Red Sea and a global structural view.

Djibouti

2020 ◽  
Author(s):  
Marius Schneider ◽  
Vanessa Ferguson
Keyword(s):  
Middle East ◽  
Red Sea ◽  
Gulf Of Aden ◽  
Horn Of Africa ◽  
Strategic Location

One of the smallest countries in Africa with a total area of 23,200 square kilometres (km) and a population of 956,000 in 2017, Djibouti is located in the Horn of Africa. It borders Eritrea, Ethiopia, Somalia, the Red Sea, and the Gulf of Aden. This strategic location makes it a bridge between the Middle East and Africa. Its capital and largest city is Djibouti city. It is the cultural and economic heart of the country. Around two-thirds of the population live in Djibouti city.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The shear along the Dead Sea rift

1970 ◽  
Vol 267 (1181) ◽  
pp. 107-130 ◽  
Keyword(s):  
Red Sea ◽  
Dead Sea ◽  
Gulf Of Aqaba ◽  
Gulf Of Aden ◽  
Present Position ◽  
East Side ◽  
Movement Rate ◽  
Left Hand ◽  
Average Shear ◽  
The Dead

Recent surface and subsurface geological investigations in Israel and Jordan provide new data for the re-examination of Dubertret’s (1932) hypothesis of the left-hand shear along the Dead Sea rift. It is found that while none of the pre-Tertiary sedimentary or igneous rock units extend right across the rift, all of them resume a reasonable palaeographical configuration once the east side of the rift is placed 105 km south of its present position. It is therefore concluded that the 105 km post-Cretaceous, left-hand shear along the Dead Sea rift is well established. The 40 to 45 km offset of Miocene rocks and smaller offsets of younger features indicate an average shear movement rate of 0.4 to 0.6 cm a -1 during the last 7 to 10 Ma. Unfortunately, the 60 km pre-Miocene movement cannot be dated yet. Along the Arava and Gulf of Aqaba and in Lebanon the shear is divided over a wide fault zone within and outside the rift.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The seismicity of the Red Sea, Gulf of Aden and Afar triangle

1970 ◽  
Vol 267 (1181) ◽  
pp. 49-74 ◽  
Keyword(s):  
Red Sea ◽  
Body Wave ◽  
Western Boundary ◽  
Earthquake Activity ◽  
Gulf Of Aden ◽  
Transform Faults ◽  
Fault Plane Solutions ◽  
Afar Depression ◽  
Sea Floor Spreading ◽  
Afar Triangle

The seismicity of the Red Sea, Gulf of Aden and Afar triangle has been studied for the period January 1953 through December 1968. Epicentres have been relocated using the method of joint Epicentral Deter­mination (Douglas 1967) and some fault plane solutions have been attempted. Magnitude-frequency studies indicate that with the present distribution of teleseismic stations, earthquakes with body wave magnitude m b ≽ 4.8 are well determined in this region. The study confirms that there is surprisingly little major earthquake activity in the northern part of the Red Sea. Between 19.5 and 21.0° N, there is a concentration of epicentres and some of these might be associated with an active NNE transform fault. In the southern part of the Red Sea, most of the epicentres are associated with the deep, axial trough, although some are associated with the western mar­gin, especially in the neighbourhood of the Gulf of Zula (15° N). Earthquake activity is confined to the centre of the Gulf of Aden with concentrations of epicentres occurring on or near to NNE transform faults. The seismically active zone continues westwards through the Gulf of Tadjoura and across the Afar depression to the western boundary scarp. There are no teleseismically recorded epicentres between latitudes 12.2 and 14.2° N. In general, most of the seismic activity occurs along the centres of the Red Sea and Gulf of Aden and this supports a sea-floor spreading mechanism for their origin. The number of plates involved is discussed.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - The Gulf of Suez: a brief review of stratigraphy and structure

1970 ◽  
Vol 267 (1181) ◽  
pp. 41-48 ◽  
Keyword(s):  
Red Sea ◽  
Upper Cretaceous ◽  
Hot Springs ◽  
Gulf Of Suez ◽  
Gulf Of Aden ◽  
Transform Faults ◽  
Clastic Sediments ◽  
Stratigraphic Record ◽  
Intrusive Activity

This paper gives a brief review of the main elements of the complex stratigraphy and structure of the Gulf of Suez, with an attempt to interpret or rather speculate on the role of lateral movements in its development. The stratigraphic record shows that the Gulf existed as a shallow embayment of the Tethys since at least the Carboniferous, and that a landmass lay at its southern end until upper Cretaceous. Predomi­nantly clastic sediments characterizing its early history changed to calcareous marine since the Cenoma­nian. Intensive faulting and subsidence, associated with volcanic and intrusive activity was evident since Upper Cretaceous, reached a maximum towards the end of Oligocene, continued through the Miocene and into the Pleistocene; hot springs are still active at present. Structurally the Gulf was divided by van der Ploeg into four provinces delineated by NNE—SSW trending ‘cross disturbances’. The four provinces appear to have formed two deep basins separated by two structural highs. It is speculated that the cross disturbances may represent transform faults between en échelon tension fissures (basins), produced as a result of a limited movement of Sinai towards the NNE relative to Africa, perhaps at a slower rate than the movement of Arabia.

scholarly journals The major tectonic boundaries of the Northern Red Sea rift, Egypt derived from geophysical data analysis

2017 ◽  
Vol 47 (3) ◽  
pp. 149-199
Author(s):  
Salah Saleh ◽  
Oya Pamukçu ◽  
Ladislav Brimich
Keyword(s):  
Heat Flow ◽  
Red Sea ◽  
Eastern Mediterranean ◽  
Gravity Anomalies ◽  
Dead Sea ◽  
Gulf Of Aqaba ◽  
Dead Sea Transform ◽  
Red Sea Rift ◽  
Low Pass ◽  
Northern Red Sea

AbstractIn the present study, we have attempted to map the plate boundary between Arabia and Africa at the Northern Red Sea rift region including the Suez rift, Gulf of Aqaba-Dead Sea transform and southeastern Mediterranean region by using gravity data analysis. In the boundary analysis method which was used; low-pass filtered gravity anomalies of the Northern Red Sea rift region were computed. Different crustal types and thicknesses, sediment thicknesses and different heat flow anomalies were evaluated. According to the results, there are six subzones (crustal blocks) separated from each other by tectonic plate boundaries and/or lineaments. It seems that these tectonic boundaries reveal complex structural lineaments, which are mostly influenced by a predominant set of NNW–SSE to NW–SE trending lineaments bordering the Red Sea and Suez rift regions. On the other side, the E–W and N–S to NNE–SSW trended lineaments bordering the South-eastern Mediterranean, Northern Sinai and Aqaba-Dead Sea transform regions, respectively. The analysis of the low pass filtered Bouguer anomaly maps reveals that the positive regional anomaly over both the Red Sea rift and South-eastern Mediterranean basin subzones are considered to be caused by the high density of the oceanic crust and/or the anomalous upper mantle structures beneath these regions whereas, the broad medium anomalies along the western half of Central Sinai with the Suez rift and the Eastern Desert subzones are attributed to low-density sediments of the Suez rift and/or the thick upper continental crustal thickness below these zones. There are observable negative anomalies over the Northern Arabia subzone, particularly in the areas covered by Cenozoic volcanics. These negative anomalies may be attributed to both the low densities of the surface volcanics and/or to a very thick upper continental crust. On the contrary, the negative anomaly which belongs to the Gulf of Aqaba-Dead Sea transform zone is due to crustal thickening (with limited heat flow values) below this region. Additionally in this study, the crustal thinning was investigated with heat flow, magnetic and free air gravity anomalies in the Northern Red Sea rift region. In fact, the crustal thinning of the study area was also proportional to the regions of observable high heat flow values. Finally, our results were found to be well correlated with the topography, free air, aeromagnetic and heat flow dataset profiles crossing most of the study area.

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

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.

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