Tectonics of the Northern Red Sea, insights from multibeam bathymetric mapping of Mabahiss Deep.

2020 ◽  
Author(s):  
Daniele Trippanera ◽  
Margherita Fittipaldi ◽  
Nico Augustin ◽  
Froukje M. van der Zwan ◽  
Sigurjón Jónsson
Keyword(s):  
Oceanic Crust ◽  
Red Sea ◽  
Spreading Rate ◽  
Ocean Floor ◽  
Tectonic Activity ◽  
Rift System ◽  
Central Volcano ◽  
The South ◽  
The North ◽  
Northern Red Sea

<p>The Red Sea is a unique place to study the birth of an oceanic rift basin and the interplay between magma and tectonics at a young divergent plate boundary. The Red Sea is a NNW-SSE oriented and 2000 km long rift system with a spreading rate decreasing from ~16 mm/yr in the south to ~7 mm/yr in the north. The morphology also changes along the rift axis: the south portion is a continuous and well-developed rift, clearly exposing oceanic crust, the central portion is characterized by deeps made by oceanic crust separated by shallower inter-trough zones, and the northern part contains more widely spaced and less obvious deeps with the transition to the continental crust not well defined. While the central Red Sea morphology has been extensively studied, the structure of the northern Red Sea and its link to the central Red Sea are still unclear. Indeed, the northern Red Sea rift is offset by 100 km to the central Red Sea axis by the still poorly understood Zabargad fracture zone.</p><p>Here we aim at improving the understanding of the volcano-tectonic structure of the axial part of the southern tip of the northern Red Sea that corresponds to the Mabahiss Deep. To this aim, we carried out multiple multibeam surveys with R/V Thuwal and R/V Kobi Ruegg to map the sea bottom to add to what had been done in earlier surveys. In addition, we obtained several sub-bottom profiling lines across and along the deep to better constrain the shallow sedimentary structure.</p><p>Our results show that the 15 km long, 9 km wide and 2250 m deep Mabahiss Deep along with the 800 m high and 5 km wide central volcano are the key prominent structures of the area. The deep is bordered by a series of Red Sea parallel normal faults on two sides forming a graben-like structure and thus suggesting a rift-like morphology. The central volcano is well preserved and has a 2 km wide summit caldera containing several volcanic cones and thus suggesting a permanent magmatic source underneath of a relatively young age. The ocean floor outside the deep and the volcanic edifice is mostly covered by salt flows, limiting structural analysis of the surrounding areas.</p><p>A comparison between the northern and central Red Sea suggests, although in both areas thick salt covers most of the ocean floor, that the axes have similar rift-like structures with stable axial volcanism. However, in the central Red Sea larger portions of the oceanic crust are free of salt and the deformation seems larger with more prominent faults that also affect the floor of the deeps and split apart volcanic edifices, enhancing the occurrence of diffused monogenic volcanic cones. Therefore, this might suggest, despite the central and northern Red Sea sharing the same structure and evolution, that the less volcanic and tectonic activity in the north probably reflects the decreasing spreading rate from south to north along the Red Sea.</p>

scholarly journals Early magmatism in the greater Red Sea rift: timing and significance

2016 ◽  
Vol 53 (11) ◽  
pp. 1158-1176 ◽  
Author(s):  
William Bosworth ◽  
Daniel F. Stockli
Keyword(s):  
Red Sea ◽  
Plate Boundary ◽  
Rift System ◽  
Northern Ethiopia ◽  
Gulf Of Suez ◽  
East African ◽  
Red Sea Rift ◽  
Lithospheric Extension ◽  
Extensional Faulting ◽  
Northern Red Sea

Throughout the greater Red Sea rift system the initial late Cenozoic syn-rift strata and extensional faulting are closely associated with alkali basaltic volcanism. Older stratigraphic units are either pre-rift or deposited during pre-rupture mechanical weakening of the lithosphere. The East African superplume appeared in northeast Africa ∼46 Ma but was not accompanied by any significant extensional faulting. Continental rifting began in the eastern and central Gulf of Aden at ∼31–30 Ma coeval with the onset of continental flood volcanism in northern Ethiopia, Eritrea, and western Yemen. Volcanism appeared soon after at Derudeb in southern Sudan and at Harrats Hadan and As Sirat in Saudi Arabia. From ∼26.5 to 25 Ma a new phase of volcanism began with the intrusion of a dike field reaching southeast of Afar into the Ogaden. At 24–23 Ma dikes were emplaced nearly simultaneously north of Afar and reached over 2000 km into northern Egypt. The dike event linked Afar to the smaller Cairo mini-plume and corresponds to initiation of lithospheric extension and rupture in the central and northern Red Sea and Gulf of Suez. By ∼21 Ma the dike intrusions along the entire length of the Red Sea were completed. Each episodic enlargement of the greater Red Sea rift system was triggered and facilitated by breakthrough of mantle-derived plumes. However, the absence of any volumetrically significant rift-related volcanism during the main phase of Miocene central and northern Red Sea – Gulf of Suez rifting supports the interpretation that plate–boundary forces likely drove overall separation of Arabia from Africa.

scholarly journals Late Oligocene–Early Miocene Nukhul Sequence, Gulf of Suez and Red Sea

GeoArabia ◽  
2012 ◽  
Vol 17 (1) ◽  
pp. 17-44 ◽  
Author(s):  
Moujahed I. Al-Husseini
Keyword(s):  
Red Sea ◽  
Isotope Analysis ◽  
Sedimentary Facies ◽  
Early Miocene ◽  
Rift System ◽  
Gulf Of Suez ◽  
Late Oligocene ◽  
Depositional Sequence ◽  
Red Sea Rift ◽  
Northern Red Sea

ABSTRACT Egypt’s Late Oligocene–Early Miocene Nukhul Formation was deposited during the earliest geological evolution of the Gulf of Suez and Red Sea Rift System. In this paper the formation is cast as a depositional sequence based on published sections, and correlated across the Gulf of Suez and northern Red Sea. The resulting correlations indicate that deposition was initiated in local grabens by the oldest continental clastics of the lower member of the Nukhul Formation, the Shoab Ali Member. The member overlies the Suez Rift Unconformity, a term proposed for the entire Red Sea. Although this member can attain a thickness of ca. 1,000 ft (305 m) locally in grabens, it is generally absent over horsts. Sedimentary facies of the member are interpreted as indicating an initial alluvial-fluvial setting that evolved to an estuarine and coastal setting. The upper part of the Nukhul Formation records a regional shallow-marine transgression, which can be subdivided into three correlative Upper Nukhul members. These sediments are absent over the highest paleo-horsts, but reach up to 900 ft (275 m) in thickness in grabens. In the southern Gulf of Suez the Ghara Member represents the Upper Nukhul members. In places it consists of four cycles, each of which starts with an anhydrite bed and is overlain by deposits of mixed lithology (sandstone, marl, and limestone). The four cycles are interpreted as transgressive-regressive subsequences that can be correlated across ca. 60 km in the Gulf of Suez. The Ghara Member correlates to Saudi Arabia’s Yanbu Formation, which consists of massive salt in wells drilled on the Red Sea coastal plains. The Yanbu Salt is dated by strontium-isotope analysis at ca. 23.1–21.6 Ma (earliest Aquitanian). The Nukhul Formation is capped by the Sub-Rudeis Unconformity or correlative Rudeis Sequence Boundary, and overlain by the Rudeis Formation. The Nukhul Formation is here proposed as the Nukhul Sequence and defined in the Wadi Dib-1 Well, wherein it consists of Nukhul subsequences 1 to 10 (in descending order, ranging in thickness between 33–84 m). The lower six Nukhul subsequences 10 to 5 are characterized by shale-to-sandstone cycles of the Shoab Ali Member, and the upper four are represented by the cycles of the Ghara Member. The 10 subsequences are interpreted as tracking the 405,000 year eccentricity signal of the Earth’s orbit and to span ca. 4.0 million years between ca. 25.0 and 21.0 Ma.

A SEAMOUNT WITH A NONMAGNETIC TOP

Geophysics ◽  
1971 ◽  
Vol 36 (2) ◽  
pp. 349-357 ◽  
Author(s):  
C. G. A. Harrison
Keyword(s):  
Magnetic Material ◽  
Magnetic Anomaly ◽  
Ocean Floor ◽  
Average Depth ◽  
Gulf Of Guinea ◽  
The South ◽  
Model Studies ◽  
The North ◽  
Paleomagnetic Pole ◽  
Best Fitting

The bathymetry and magnetic anomaly of a seamount in the Gulf of Guinea have been surveyed. The seamount is regular in shape and rises about 2000 m to a depth of 2650 m at the peak. The magnetic anomaly is well developed and consists of a low to the north and a high to the south of the peak, the field changing by 700 gammas between these points. In an attempt to duplicate the observed anomaly by model studies, it was found that despite the regularity of the observed anomaly, only a poor fit could be obtained when the seamount was modeled with a body equivalent to the topographic shape. The best fitting calculated anomaly was of shorter wavelength than the observed anomaly, suggesting that the average depth to the magnetic material is deeper than the topography indicates. Further model studies have shown that the top portion of the seamount is relatively much less magnetic than the rest and that there is magnetic material below the level of the surrounding ocean floor. The nonmagnetic top of the seamount is explained by the hypothesis of Bonatti and Nayudu, calling for intense alteration of basalt to palagonite and smectites, which have a very low magnetization. This alteration would be more intense at the top of a seamount and would thus cause a relatively nonmagnetic top. Other published seamount surveys contain many examples where the same thing appears to occur. The changes in direction of magnetization produced by the various models for the seamounts are very small; hence, the original paleomagnetic pole positions should not be in error by more than a few degrees. The paleomagnetic significance of results from seamounts is not affected.

Crustal contamination and hybridization of an embryonic oceanic crust during the Red Sea rifting: An example from the Tihama Asir igneous complex, Saudi Arabia

2021 ◽  
Author(s):  
Valentin Basch ◽  
Alessio Sanfilippo ◽  
Luigi Vigliotti ◽  
Antonio Langone ◽  
Najeeb Rasul ◽  
...  
Keyword(s):  
Continental Crust ◽  
Oceanic Crust ◽  
Red Sea ◽  
Crustal Contamination ◽  
Seafloor Spreading ◽  
Rift System ◽  
Continental Rifting ◽  
Igneous Complex ◽  
Early Stages ◽  
Incompatible Elements

<p>The Red Sea rift system represents the best case study of the rift-to-drift history, i.e., the transition from a continental to an oceanic rift and the formation of passive margins. Although the onset of seafloor spreading has been constrained by geophysical observations to 5 Ma in the southern Red Sea, recent studies have suggested that MORB-type melts were intruded within the extended continental crust already during the early stages of rifting. We present here a petro-geochemical investigation of gabbroic bodies and associated basaltic intrusions from the Tihama Asir igneous complex, which formed as part of the intense magmatism that occurred during early Red Sea continental rifting. The most primitive olivine gabbros present modal, bulk and mineral compositions consistent with formation from MORB-type parental melts, but more evolved gabbros and oxide gabbros show saturation of phlogopite and define a geochemical evolution that progressively diverges from that of lower oceanic crust at mid-ocean ridges. Indeed, the Tihama Asir evolved gabbros are characterized by enrichments in LREE and highly incompatible elements (Rb, Ba, U, Th, Nb, Sr, K), suggesting hybridization of a MORB-type parental melt through a process of progressive assimilation of continental crust during the emplacement of gabbroic bodies. Additionally, the gabbros are associated with basaltic dike swarms intruded into the extending continental crust. The basalts show enrichments in LREE and highly incompatible elements similar to the gabbros, suggesting that they formed from melts extracted from the hybridized gabbroic crystal mush. This indicates that the Red Sea oceanization started before the onset of seafloor spreading, and that the cold continental crust was partially assimilated and replaced by hot gabbroic bodies since the early stages of continental rifting.</p>

scholarly journals The evolution of the Massif Central Rift; spatio-temporal distribution of the volcanism

2001 ◽  
Vol 172 (2) ◽  
pp. 201-211 ◽  
Author(s):  
Laurent Michon ◽  
Olivier Merle
Keyword(s):  
Central Area ◽  
Temporal Distribution ◽  
Rift System ◽  
The South ◽  
Volcanic Event ◽  
Quaternary Volcanism ◽  
Massif Central ◽  
Lithospheric Thinning ◽  
The North ◽  
Magmatic Event

Abstract The Massif Central area is the largest magmatic province of the West-European Rift system. The spatial-temporal distribution of Tertiary-Quaternary volcanism in the Massif Central, France, shows that three magmatic phases can be defined, each of them characterized by different volumes and different locations. The first event, termed the pre-rift magmatic event, is very scarce and restricted to the north of the Massif Central. It is suggested that this could result from lithospheric bending of the European lithosphere ahead of the incipient Alpine chain during the Paleocene. The second event, termed the rift-related magmatic event, is located in the north of the Massif Central only and is spatially connected with zones of high crustal thinning (i.e. the Limagne graben). It immediately follows Oligocene graben formation and associated sedimentation, and is represented by more than 200 scattered monogenic edifices. This second event can be attributed to partial melting as a consequence of lithospheric thinning that affected the north of the Massif Central during the rifting event. The lack of volcanism in the south during the same period of time is probably related to the very slight lithospheric thinning during the Oligocene. The third event, termed the major magmatic event, started first in the south in the upper Miocene at about 15 Ma, well after the end of the sedimentation. It is unrelated to any extensional event. This major magmatic event reached the north of the Massif Central at about 3.5 Ma, following a pause in volcanism of about 6 Ma after the rift-related magmatic event. These two episodes of the major magmatic event are spatially and temporally associated with the two main periods of uplift, suggesting a common origin for volcanism and uplift processes. The major magmatic event can be attributed to late thermal erosion of the base of the lithosphere above a mantle diapir, as suggested by seismic tomography data. This general magmatic evolution drawn from data at the Massif Central scale may apply to the Eger graben as well, as the three magmatic events described in this study (pre-rift magmatic event, rifting event and post-Miocene volcanic event) are also reported in the literature. This suggests that a single cause should explain the formation of the entire western European rift surrounding the Alpine mountain belt.

scholarly journals Tourism Impact on Marine Ecosystems in the North of Red Sea

2019 ◽  
Vol 13 (1) ◽  
pp. 10
Author(s):  
Abderrahim Lakhouit
Keyword(s):  
Coral Reefs ◽  
Red Sea ◽  
Human Activities ◽  
Marine Ecosystems ◽  
Tourism Impact ◽  
The North ◽  
Algae Blooms ◽  
Marine Habitats ◽  
The Impact ◽  
Northern Red Sea

The unique marine environment of the northern Red Sea region is among the richest and most productive marine ecosystems in the world. The sea is populated with extensive algae blooms and at least five types of coral reefs. However, the region’s tourism sector is largely dependent on the surrounding environment, including the coral reefs, which are highly sensitive to human activities. A large tourist project (Neom) is scheduled to be installed in the northern Red Sea, further increasing tourist activities in the area and leading to human intrusion into crucial but fragile marine habitats such as seagrass beds, coral reefs and mangrove stands. The present study investigates how human activities are currently affecting Red Sea ecosystems. Field visits were done in order to investigate and to study human activities impact on marine ecosystems in the north of Red Sea. To the best of our knowledge, this work is the first of its kind to evaluate the impact of tourism on marine ecosystems in Saudi Arabia’s northern Red Sea coast.

The Northern Red Sea - a model for rifting leading to continental break-up

2021 ◽  
Author(s):  
Ken McClay ◽  
Bill Bosworth ◽  
Samir Khalil ◽  
Marco Ligi ◽  
Danny Stockli
Keyword(s):  
Red Sea ◽  
Depositional Environments ◽  
Entire Length ◽  
Fault System ◽  
Gulf Of Aqaba ◽  
Rift System ◽  
Gulf Of Suez ◽  
Block Rotation ◽  
Red Sea Rift ◽  
Northern Red Sea

<p>The Gulf of Suez and the Northern Red Sea form the northwestern sector of the Afro-Arabian rift system.  Studies of outstanding outcrops of rift fault systems and syntectonic strata integrated with sub-surface data together with thermo-chronological studies indicate that the Gulf of Suez - Northern Red Sea rift system initiated at around the Oligocene to Miocene transition (24 to 23 Ma).  A regional NW-SE trending Oligocene-Miocene (~23 Ma) alkali basalt dike swarm and basalt flows near Cairo, appears to mark the onset of crustal-scale extension and continental rifting.  These dikes and scarce local flows, are interbedded with the oldest siliciclastic syn-rift strata (Aquitanian Nukhul Fm.), and are associated with the oldest recognized extensional faulting in the Red Sea.  Bedrock thermochronometric results from the Gulf of Suez and both margins of the Red Sea also point to a latest Oligocene onset of major normal faulting and rift flank exhumation and large-magnitude early Miocene extension along the entire length of the Red Sea rift.  The early phase of rifting produced complex, discontinuous fault patterns with very high rates of fault block rotation, distinct sub-basins with alternating regional dip domains separated by well-defined accommodation zones.  Sedimentary facies were laterally and vertically complex and dominated by marginal to shallow marine siliciclastics of the Abu Zenima, Nukhul and Nakheil Formations.  Neotethyan faunas appeared throughout all of the sub-basins at this time.  During the Early Burdigalian (~20 Ma) tectonically-driven subsidence accelerated and was accompanied by a concordant increase in denudation and uplift of the rift shoulders.  The intra-rift fault networks coalesced into through-going structures and extension became progressively more focused along the rift axis.  This reconfiguration resulted in more laterally continuous depositional facies and the moderate-to-deep marine deposits of the Rudeis, Kareem and Ranga Formations.<br>At the early Middle Miocene (~14 Ma) onset of the left-lateral Gulf of Aqaba transform fault system marked dramatic changes in rift kinematics and sedimentary depositional environments.  The Gulf of Suez became isolated from the active northern Red Sea rift, with a switch from orthogonal to oblique rifting and to hyperextension in the northern Red Sea.  The previous open marine seaway was replaced by an extensive evaporitic basin along the entire length of the rift from the central Gulf of Suez to Yemen/Eritrea.  In Egypt these evaporites are ascribed to the Belayim, South Gharib, Zeit and Abu Dabbab Formations.  Evaporite deposition continued to dominate until the end of the Miocene (~5 Ma) when a subaerial unconformity developed across most of the basins. With the onset of seafloor spreading in the southern Red Sea, Indian Ocean marine waters re-entered through the Bab el Mandab in the earliest Pliocene and re-established open marine conditions.  In the northern Red Sea well and seismic data demonstrate that continental crust extends at least several tens of kilometers offshore.  The northern Red Sea is a highly extended non-volcanic rift and true, laterally integrated sea-floor spreading has not yet developed.</p>

General Geology

1995 ◽  
Author(s):  
K. O. Emery ◽  
David Neev
Keyword(s):  
Red Sea ◽  
Dead Sea ◽  
Strike Slip ◽  
The South ◽  
The West ◽  
The North ◽  
Central Segment ◽  
Crystalline Crust ◽  
Major Fault ◽  
The Dead

The Dead Sea occupies a linear down-dropped region between two roughly parallel faults along the central segment of the major northsouth- trending crustal rift that extends about 1,100 km from the Red Sea through the Gulf of Elath to Turkey. This rift or geosuture separates the Arabian crustal sub-plate on the east from the Sinai one on the west. An origin as early as Precambrian is possible (Bender, 1974; Zilberfarb, 1978). Crystalline crust along the north-south trough of the Sinai sub-plate is about 40 km thick in contrast with a thickness of half as much above ridges along both flanks (Ginsburg and Gvirtzman, 1979). Toward the north the ridges appear to converge (Neev, Greenfield, and Hall, 1985). Since the Miocene period the Arabian plate has moved north about 105 km relative to the Sinai plate. This sort of crustal movement along either side of a rift is termed strike-slip faulting. One result of it was the opening of the Red Sea relative to the Gulf of Suez. The Dead Sea graben, a down-dropped block between two roughly parallel faults, occupies the central segment of the long crustal rift. The boundary between these is rather sharp along the east shore of the sea (Frieslander and Ben-Avraham, 1989). Actual post-Miocene movement was along not just a single major fault but was distributed among numerous sub-parallel faults that form a 100-km-wide belt in which movements were transferred from one fault to another (Eyal et al., 1981; Gilat and Honigstein, 1981). Recent movements have occurred along the south segment of the north-south-trending Arava fault south of the Amazyahu transverse fault (Zak and Freund, 1966). These strike-slip movements probably did not continue after Miocene along the main East fault of the Dead Sea, which is the north extension of the Arava wrench fault. In contrast, recent movements have been present along the north-northeast- trending Jordan or Dead Sea fault (Ben-Menahem et al., 1977, fig. 1). The movements extend south from east of Jericho in the north along the base of the west submarine slope of the sea and the elongate salt diapir of Mount Sedom as far as the Amazyahu fault in the south.

A statistical study of 238U and 234U/238U distributions in coral samples from the Egyptian shoreline of the north-western Red Sea and in fossil mollusk shells from the Atlantic coast of High Atlas in Morocco: Implications for 230Th/234U dating

2002 ◽  
Vol 90 (6) ◽  
Author(s):  
A. Choukri ◽  
J.-L. Reyss ◽  
O.K. Hakam ◽  
J. C. Plaziat
Keyword(s):  
Red Sea ◽  
Statistical Study ◽  
Atlantic Coast ◽  
Radiochemical Analysis ◽  
Statistical Distributions ◽  
The South ◽  
High Atlas ◽  
Mollusk Shells ◽  
The North ◽  
North Western

SummaryIn this work, radiochemical analysis results of 126 unrecrystallized coral samples from the Egyptian shoreline of northwestern Red Sea and 120 fossil mollusk shell samples from the Atlantic coast of Moroccan High Atlas at the North of Agadir City in Morocco are presented and discussed. The coral samples were collected in Egypt from the emerged coral reef terraces over 500 km from The Ras Gharib-Ras Shukeir depression (28°10') in the north to Wadi Lahami (north of Ras Banas, 24°10') in the south. The fossil mollusk shells were collected in Morocco from Agadir-Harbour in the south to Tamri village in the north extending over about 50 km. The statistical distributions of results (For corals,For mollusk shells, except for Holocene sea level,

Calcareous sponges (Porifera, Calcarea) from Ilha Grande Bay, Brazil, with descriptions of three new species

Zootaxa ◽  
2007 ◽  
Vol 1402 (1) ◽  
pp. 1 ◽  
Author(s):  
FERNANDA AZEVEDO ◽  
MICHELLE KLAUTAU
Keyword(s):  
New Species ◽  
Red Sea ◽  
Geographic Distribution ◽  
Rio De Janeiro ◽  
The South ◽  
Southwest Coast ◽  
Calcareous Sponges ◽  
The North ◽  
Three New Species ◽  
Janeiro State

This is the first surveillance of calcareous sponges (Porifera, Calcarea) from Ilha Grande Bay in the Southwest coast of Rio de Janeiro, Brazil. Two islands were surveyed and the description of the calcareous sponges collected is presented here. A total of 98 specimens were collected, from five species. Clathrina aspina has its geographic distribution extended to the South of Rio de Janeiro state; Sycettusa cf. hastifera, a species from the Red Sea, and previously cited to the North of Rio de Janeiro state, was now found in Ilha Grande Bay; three new species to science are being described here: Clathrina angraensis sp. nov., Leucandra serrata sp. nov., and Paraleucilla perlucida sp. nov.

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