Contrasting structural styles of the eastern and western margins of the southern Red Sea: the 1988 SONNE experiment

Egloff, F.; Rihm, R.; Makris, J.; Izzeldin, Y.A.; Bobsien, M.; Meier, K J Sebastian; Junge, P.; Noman, T.; Warsi, Waris E. K.

doi:10.1016/0040-1951(91)90159-p

Cited by 66 publications

(63 citation statements)

References 16 publications

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“…10) has been analyzed and compared with reflection seismic profiles in the region. Assuming the density and velocity of the different layers from sediments to mantle as proposed by Egloff et al (1991), a synthetic reflection seismic profile was obtained (Mohriak et al 2010). Interpretation of the refraction profile P1 and its comparison with seismic data from the Red Sea suggests a conceptual model for the conjugate margins in the Red Sea indicative of a very rapid thinning of the continental crust from onshore to offshore (Fig.…”

Section: " "mentioning

confidence: 99%

“…10), and the thickening of the salt basin beyond the shelfbreak appears to be similar to that observed in South Atlantic basins. The transition from continental crust to oceanic crust is marked by refraction velocities between 5 and 6 km/s, which might be associated with an igneous crust (Egloff et al 1991). The transition from this crust to the upper mantle rocks is very abrupt and marked by the Moho discontinuity at 5-8 km below sea level.…”

Section: " "mentioning

confidence: 99%

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Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Mohriak

Leroy

2012

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To cite this version:Webster Ueipass Mohriak, Sylvie Leroy. Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea-Gulf of Aden conjugate margins. Special Publication -Geological Society of London, 2012, 369, pp.1-40. <10.1144/SP369.17>. !" " " ARCHITECTURE OF RIFTED CONTINENTAL MARGINS AND BREAKUP EVOLUTION: INSIGHTS FROM THE SOUTH ATLANTIC, NORTH ATLANTIC AND RED SEA -GULF OF ADEN CONJUGATE MARGINS

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Section: " "mentioning

confidence: 99%

Section: " "mentioning

confidence: 99%

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Mohriak

Leroy

2012

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“…Except for a narrow axial trough that exposes basaltic crust, this basin is underlain by sediments, up to 4-6 km thick, much of which consist of c. 16 to 5 Ma old (Middle and Late Miocene) evaporires (Coleman 1984;Hughes & Beydoun 1992;Mitchell et al 1992). The underlying crust is thin (<10 km), but it probably varies across the basin Egloff et al 1991;Prodehl & Mechie 1991;Cochran 2005). The central third of the basin, especially in its southern two-thirds, is characterized by an accentuated Bouguer gravity high, and may well be underlain by oceanic crust.…”

Section: Continental Break-up Stagementioning

confidence: 99%

Constraints on the structural development of Afar imposed by the kinematics of the major surrounding plates

Garfunkel

Beyth

2006

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The development of the Afar rift-rift-rift triple junction is analysed from the viewpoint of the Nubia, Arabia and Somali plate kinematics. A variety of constraints allow definition of a range of kinematic models that approximate well to the plate motions with a resolution of a couple to tens of kilometres. Rigid plate kinematics probably cannot resolve smaller motions. The size and location of the new area that opened between the major plates is inferred from plate kinematics and this provides a framework in which to assess the structural development that accommodates plate separation.The development of the Afar region was complicated by the presence of microplates -the Danakil and Aisha blocks -which results in a complex plate boundary geometry. This led to local deformation that does not directly reflect the divergence of the major plates, e.g. rotations of microplates and of minor blocks about vertical axes and strike-slip faulting. The opening of new area was accommodated by various crustal growth and accretion mechanisms, e.g. building of thick new igneous crust, normal seafloor spreading, and/or crustal stretching. Thus, plate motions by themselves do not determine the development of the plate boundaries, as this is strongly influenced by other factors such as lateral variations of the rates of magma supply (e.g. away from, and over, the Afar plume).The plate boundaries changed -e.g. the Gulf of Aden spreading centre propagated westward c. 2 Ma ago and normal seafloor spreading began along portions of the Red Sea axis since c. 5 Ma ago -while there were no resolvable changes in the plate motions. Such changes therefore signify a reorganization of the way in which plate divergence and addition of new area is accommodated: diffuse extension may give way to separation along a narrow spreading centre, or new plate boundaries may form at the expense of other boundaries that became inactive. et al.

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“…Most of the strong earthquakes occurred before the installation of the regional broad-band stations, or the stations were not operational. The velocity models (see Table 2) are based on the refraction studies of Makris & Ginzburg (1987), Voggenreiter et al (1988) and Egloff et al (1991). Dreger & Helmberger (1991 have shown that one can use regional broad-band data, complete waveform including body and surface waves in the frequency range below 0.1 Hz, for the waveform inversion of local and regional events.…”

Section: S O U Rc E M E C H a N I S M Smentioning

confidence: 99%

“…5(a) (M W ∼ 5 and ∼6) bear more regional tectonic significance than those of Fig. Makris & Ginzburg 1987;Voggenreiter et al 1988;Egloff et al 1991) used in the calculation of Green's functions for the path to the stations AAE, ATD, AGD, FURI and SODA. Makris & Ginzburg 1987;Voggenreiter et al 1988;Egloff et al 1991) used in the calculation of Green's functions for the path to the stations AAE, ATD, AGD, FURI and SODA.…”

Section: S O U Rc E M E C H a N I S M Smentioning

confidence: 99%

The Afar Depression: interpretation of the 1960-2000 earthquakes

Hofstetter

Beyth

2003

Geophysical Journal International

102

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SUMMARY We studied the seismic activity of the Afar Depression (AD) and adjacent regions during the period 1960–2000. We define seven distinct seismogenic regions using geological, tectonic and seismological data. Based on the frequency–magnitude relationships we obtain b‐values of about 1 for the different regions. The pattern of the distribution of the location of epicentres fits with the known active fault zone in the AD and the axial volcanic ridges. The Bab el Mandab area and the Danakil‐Aysha'a blocks are less active. For 125 intermediate to strong earthquakes the seismic moment and source parameters were calculated. The results of the fault plane solutions for the Afar Depression indicate mainly strike‐slip and normal sense of movement originating from fault planes striking NW–SE. These results indicate a clockwise block rotation described previously as a bookshelf model in central AD. There are a few right‐lateral faults east of Massawa with E–W‐striking fault planes. At the southern Red Sea, north of the Danakil block, the mixed focal mechanisms, with axial plane striking NW–SE, comprise several reverse faulting, strike‐slip motion and normal faulting. Right‐lateral movement was also calculated for a cluster of seismic events between the Manda Hararo and Alyata volcanic ridges along NW–SE‐striking faults. Along the N–S‐striking faults in the escarpment, at the western Afar margins, there are two distinct clusters of epicentres. The strong earthquakes at the southern cluster exhibit normal or strike‐slip motions. The intermediate to small earthquakes in the northern cluster exhibit reverse and strike‐slip motions. Mainly normal faults were calculated along NE–SW‐striking faults of the Ethiopian East African Rift. Estimates of the seismic efficiency suggest that the maximal values are about 50 per cent or less, implying that most of the motion is taken aseismically.

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Contrasting structural styles of the eastern and western margins of the southern Red Sea: the 1988 SONNE experiment

Cited by 66 publications

References 16 publications

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Architecture of rifted continental margins and break-up evolution: insights from the South Atlantic, North Atlantic and Red Sea–Gulf of Aden conjugate margins

Constraints on the structural development of Afar imposed by the kinematics of the major surrounding plates

The Afar Depression: interpretation of the 1960-2000 earthquakes

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