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 - Continuous seismic reflexion profiles in the Red Sea

1970 ◽  
Vol 267 (1181) ◽  
pp. 143-152 ◽  
Keyword(s):  
Red Sea ◽  
Spreading Rate ◽  
Seafloor Spreading ◽  
Gulf Of Aden ◽  
Seismic Profiles ◽  
Main Trough ◽  
Spreading Rates ◽  
Sediment Layers ◽  
Seismic Reflector ◽  
Good Agreement

Twenty continuous seismic reflexion profiles have been made across the main trough of the Red Sea north of 17° N latitude. The main trough is characterized by mildly deformed sediment layers along the margins with highly disturbed materials in the deeper axial trough. A strong seismic reflector is observed at depths up to 500 m beneath the main trough, but is not found in the axial trough. This reflector may represent an unconformity of late Miocene-Early Pliocene age (5 to 6 Ma ago). On the assumption that this unconformity was once continuous across the main trough but has subsequently rifted apart as a result of seafloor spreading in the axial trough, separation distances of 48 to 74 km across the trough imply a minimum seafloor spreading rate of 0.4 to 0.7 cm a -1 . This rate is lower than spreading rates inferred from magnetic anomaly profiles in the Red Sea; however, if separation began as late as 2 to 3 Ma ago which can be inferred from the seismic profiles, a rate of 1.4 to 0.9 cm a -1 is indicated. This rate is in good agreement with those determined from magnetic profiles.

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 anomalies in the Red Sea

1970 ◽  
Vol 267 (1181) ◽  
pp. 205-217 ◽  
Keyword(s):  
Magnetic Anomaly ◽  
Red Sea ◽  
Central Region ◽  
Magnetic Anomalies ◽  
Seafloor Spreading ◽  
Gulf Of Aden ◽  
Close Correspondence ◽  
Trend Direction

Marine magnetic profiles over the Red Sea between 18° N and 25° N latitudes confirm previous hypotheses that strongly magnetic rocks underlie the axial trough. The symmetrical nature of the anomalies and their close correspondence to seafloor spreading magnetic models support a rifting origin for the trough. The dominant magnetic anomaly trends strike about N 35° W in the northern and southern parts of the trough. In the central region between 20° and 22° N the trend direction is about N 60° E. Geometrical considerations of possible spreading mechanisms suggest that the true separation direction of Africa away from Arabia near 21° N latitude is in either a N 10° E or N 60° E direction. The separation rates then are 3.2 cm a -1 and 2.0 cm a -1 , respectively.

scholarly journals Temporal evolution of Red Sea temperatures based on insitu observations (1958–2017)

2019 ◽  
Author(s):  
Miguel Agulles ◽  
Gabriel Jordà ◽  
Burt Jones ◽  
Susana Agustí ◽  
Carlos M. Duarte
Keyword(s):  
Red Sea ◽  
Synthetic Data ◽  
Optimal Interpolation ◽  
Strong Impact ◽  
Gulf Of Aden ◽  
Mapping Algorithm ◽  
Air Temperatures ◽  
Spatio Temporal ◽  
Good Agreement

Abstract. The Red Sea holds one of the most diverse marine ecosystems in the world, although fragile and vulnerable to ocean warming. Several studies have analysed the spatiotemporal evolution of the temperature in the Red Sea using satellite data, thus focusing only on the surface layer and covering the last ∼30 years. To better understand the long-term variability and trends of the temperature in the whole water column, we produce a 3D gridded temperature product (TEMPERSEA) for the period 1958–2017, based on a large number of in situ observations, covering the Red Sea and the Gulf of Aden. After a specific quality control, a mapping algorithm based on optimal interpolation has been applied to homogenize the data. Also, an estimate of the uncertainties of the product has been generated. The calibration of the algorithm and the uncertainty computation has been done through sensitivity experiments based on synthetic data from a realistic numerical simulation. TEMPERSEA has been compared to satellite observations of sea surface temperature for the period 1981–2017, showing good agreement specially in those periods with a reasonable number of observations were available. Also, very good agreement has been found between air temperatures and reconstructed sea temperatures in the upper 100 m for the whole period 1958–2017 enhancing the confidence on the quality of the product. The product has been used to characterize the spatio-temporal variability of the temperature field in the Red Sea and the Gulf of Aden at different time scales (seasonal, interannual and multidecadal). Clear differences have been found between the two regions suggesting that the Red Sea variability is mainly driven by air-sea interactions, while in the Gulf of Aden, the lateral advection of water also plays a relevant role. Regarding long term evolution, our results show only positive trends above 40 m depth, with maximum trends of 0.045 + 0.016 ºC decade-1 at 15 m, and the largest negative trends at 125 m (-0.072 + 0.011 ºC decade-1). Multidecadal variations have a strong impact on the trend computation, and restricting them to the last 30–40 years of data can bias high the trend estimates.

The African continental divide: Indian versus Atlantic Ocean spreading during Gondwana dispersal

2022 ◽  
Author(s):  
Alexander L. Peace ◽  
Jordan J.J. Phethean
Keyword(s):  
Indian Ocean ◽  
Atlantic Ocean ◽  
Plate Tectonics ◽  
Spreading Rate ◽  
Seafloor Spreading ◽  
Plate Tectonic ◽  
The Indian Ocean ◽  
The Mean ◽  
Spreading Rates ◽  
Indian And Atlantic Oceans

ABSTRACT It is well established that plate-tectonic processes operate on a global scale and that spatially separate but temporally coincident events may be linked. However, identifying such links in the geological record and understanding the mechanisms involved remain speculative. This is particularly acute during major geodynamic events, such as the dispersal of supercontinents, where multiple axes of breakup may be present as well as coincidental collisional events. To explore this aspect of plate tectonics, we present a detailed analysis of the temporal variation in the mean half rate of seafloor spreading in the Indian and Atlantic Oceans, as well as plate-kinematic attributes extracted from global plate-tectonic models during the dispersal of Gondwana since ca. 200 Ma. Our analysis shows that during the ~20 m.y. prior to collision between India and Asia at ca. 55 Ma, there was an increase in the mean rate of seafloor spreading in the Indian Ocean. This manifests as India rapidly accelerating toward Asia. This event was then followed by a prompt deceleration in the mean rate of Indian Ocean seafloor spreading after India collided with Asia at ca. 55 Ma. Since inception, the mean rate of seafloor spreading in the Indian Ocean has been generally greater than that in the Atlantic Ocean, and the period of fastest mean half spreading rate in the Indian Ocean was coincident with a slowdown in mean half seafloor spreading rate in the competing Atlantic Ocean. We hypothesize that faster and hotter seafloor spreading in the Indian Ocean resulted in larger ridge-push forces, which were transmitted through the African plate, leading to a slowdown in Atlantic Ocean spreading. Following collision between India and Asia, and a slowdown of Indian Ocean spreading, Atlantic spreading rates consequently increased again. We conclude that the processes in the Indian and Atlantic Oceans have likely remained coupled throughout their existence, that their individual evolution has influenced each other, and that, more generally, spreading in one basin inevitably influences proximal regions. While we do not believe that ridge push is the main cause of plate motions, we consider it to have played a role in the coupling of the kinematic evolution of these oceans. The implication of this observation is that interaction and competition between nascent ocean basins and ridges during supercontinent dispersal exert a significant control on resultant continental configuration.

scholarly journals Temporal evolution of temperatures in the Red Sea and the Gulf of Aden based on in situ observations (1958–2017)

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 149-166
Author(s):  
Miguel Agulles ◽  
Gabriel Jordà ◽  
Burt Jones ◽  
Susana Agustí ◽  
Carlos M. Duarte
Keyword(s):  
Red Sea ◽  
Temporal Evolution ◽  
Optimal Interpolation ◽  
Strong Impact ◽  
Gulf Of Aden ◽  
In Situ Observations ◽  
Spatio Temporal ◽  
Good Agreement

Abstract. The Red Sea holds one of the most diverse marine ecosystems in the world, although fragile and vulnerable to ocean warming. Several studies have analysed the spatio-temporal evolution of temperature in the Red Sea using satellite data, thus focusing only on the surface layer and covering the last ∼30 years. To better understand the long-term variability and trends of temperature in the whole water column, we produce a 3-D gridded temperature product (TEMPERSEA) for the period 1958–2017, based on a large number of in situ observations, covering the Red Sea and the Gulf of Aden. After a specific quality control, a mapping algorithm based on optimal interpolation have been applied to homogenize the data. Also, an estimate of the uncertainties of the product has been generated. The calibration of the algorithm and the uncertainty computation has been done through sensitivity experiments based on synthetic data from a realistic numerical simulation. TEMPERSEA has been compared to satellite observations of sea surface temperature for the period 1981–2017, showing good agreement especially in those periods when a reasonable number of observations were available. Also, very good agreement has been found between air temperatures and reconstructed sea temperatures in the upper 100 m for the whole period 1958–2017, enhancing confidence in the quality of the product. The product has been used to characterize the spatio-temporal variability of the temperature field in the Red Sea and the Gulf of Aden at different timescales (seasonal, interannual and multidecadal). Clear differences have been found between the two regions suggesting that the Red Sea variability is mainly driven by air–sea interactions, while in the Gulf of Aden the lateral advection of water plays a relevant role. Regarding long-term evolution, our results show only positive trends above 40 m depth, with maximum trends of 0.045 + 0.016 ∘C decade−1 at 15 m, and the largest negative trends at 125 m (-0.072+0.011 ∘C decade−1). Multidecadal variations have a strong impact on the trend computation and restricting them to the last 30–40 years of data can bias high the trend estimates.

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 evolution of the Gulf of Aden

1970 ◽  
Vol 267 (1181) ◽  
pp. 227-266 ◽  
Keyword(s):  
Red Sea ◽  
Evolutionary History ◽  
Gulf Of Aden ◽  
Fracture Zones ◽  
The West ◽  
Anomaly Field ◽  
The Past ◽  
History Of ◽  
International Indian Ocean Expedition ◽  
Spreading Rates

Marine geological and geophysical data from the International Indian Ocean Expedition, especially from cruise 16 of R. R. S. Discovery , have made it possible to prepare new charts of the bathymetry and the magnetic anomaly field which, together with other data, enable the evolutionary history of the Gulf of Aden to be worked out. Over the past 10 Ma the theory of seafloor spreading can account satisfactorily for the features of the Sheba Ridge and provides evidence of spreading rates in the direction of the fracture zones varying from 0.9 cm a -1 per limb in the west to 1.1 cm a -1 per limb in the east. Between the initial creation of the Gulf and 10 Ma ago, the evolution is less certain, although the geophysical evidence indicates that the crustal structure of the Gulf outside the Sheba Ridge is oceanic.

scholarly journals Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial

2011 ◽  
Vol 7 (2) ◽  
pp. 1195-1233 ◽  
Author(s):  
G. Trommer ◽  
M. Siccha ◽  
E. J. Rohling ◽  
K. Grant ◽  
M. T. J. van der Meer ◽  
...  
Keyword(s):  
Sea Level ◽  
Red Sea ◽  
Planktonic Foraminifera ◽  
Gulf Of Aden ◽  
Last Interglacial ◽  
The Holocene ◽  
Circulation Mode ◽  
Monsoon Strength ◽  
Mis 5E ◽  
Mis 5

Abstract. This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktonic foraminiferal fauna following high salinities during MIS 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktonic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea SST increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktonic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktonic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.

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