Donnees nouvelles sur la stratigraphie et l'histoire geologique du Dhofar (sultanat d'Oman)

Roger, Jack; Platel, Jean-Pierre; Cavelier, C.; Bourdillon-de-Grissac, C.

doi:10.2113/gssgfbull.v.2.265

Cited by 85 publications

(74 citation statements)

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“…Further to the east, the non-volcanic margins are characterized on land by coastal plains bounded by normal faults and rift shoulders. The northern margin crops out in Yemen (Huchon and Khanbari, 2003) and in the Dhofar region of southern Oman (Roger et al, 1989;Bellahsen, 2002;Lepvrier et al, 2002). The southern margin crops out in Somalia (Fantozzi, 1996;Fantozzi and Sgavetti, 1998;Fantozzi and Ali-Kassim, 2002) and in the Socotra and Abd'Al Kuri Islands (Birse et al, 1997;Samuel et al, 1997;Fig.…”

Section: Major Features Of the Gulf Of Adenmentioning

confidence: 99%

From rifting to spreading in the eastern Gulf of Aden: a geophysical survey of a young oceanic basin from margin to margin

et al. 2004

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A geophysical survey in the eastern Gulf of Aden, between the Alula–Fartak (52°E) and the Socotra (55°E) transform faults, was carried out during the Encens–Sheba cruise. The conjugate margins of the Gulf are steep, narrow and asymmetric. Asymmetry of the rifting process is highlighted by the conjugate margins (horst and graben in the north and deep basin in the south). Two transfer fault zones separate the margins into three segments, whereas the present‐day Sheba Ridge is divided into two segments by a transform discontinuity. Therefore segmentation of the Sheba Ridge and that of the conjugate margins did coincide during the early stages of oceanic spreading. Extensive magma production is evidenced in the central part of the western segment. Anomaly 5d was identified in the northern and southern parts of the oceanic basin, thus confirming that seafloor spreading in this part of Gulf of Aden started at least 17.6 Ma ago.

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Section: Major Features Of the Gulf Of Adenmentioning

confidence: 99%

From rifting to spreading in the eastern Gulf of Aden: a geophysical survey of a young oceanic basin from margin to margin

et al. 2004

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“…The rifting which started 35 Ma ago (Roger et al 1989;Bott et al 1992;Watchorn et al 1998), coincides with the climax of the Afar hotspot activity (Hofmann et al 1997;Ebinger & Sleep 1998;Kenea et al 2001;Leroy et al 2010a) and the onset of the seafloor spreading occurred at least 17.6 Ma ago in the eastern part (Leroy et al 2004;d'Acremont et al 2006;Leroy et al 2010b). Previous studies of the eastern Gulf of Aden, between Alula-Fartak and Socotra-Hadbeen fracture zones, show that the passive margins are non-volcanic (no SDRs are observed) and outcrops on land (in Southern Oman in Dhofar and Socotra, Roger et al 1989;d'Acremont et al 2005;Bellahsen et al 2006;Autin et al 2010;Leroy et al 2010b, Fig. 1).…”

Section: G E O L O G I C a L S E T T I N G S O F T H E G U L F O F A mentioning

confidence: 99%

“…Pre-rift sediments in the Gulf of Aden are known to be mostly Cretaceous to Lower Tertiary limestone (e.g. Roger et al 1989;Brannan et al 1997). Thus, the pre-rift sediments are probably strongly compacted, showing a high P-wave velocity (5.5 km s −1 ) which can be higher than the oceanic L2 velocity.…”

Section: Upper and Lower Acoustic Basementsmentioning

confidence: 99%

The crustal structure of the north-eastern Gulf of Aden continental margin: insights from wide-angle seismic data

Watremez¹,

Leroy

Rouzo³

et al. 2010

Geophysical Journal International

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International audienceThe wide-angle seismic (WAS) and gravity data of the Encens survey allow us to determinethe deep crustal structure of the north-eastern Gulf of Aden non-volcanic passive margin.The Gulf of Aden is a young oceanic basin that began to open at least 17.6 Ma ago. Itscurrent geometry shows first- and second-order segmentation: our study focusses on theAshawq–Salalah second-order segment, between Alula–Fartak and Socotra–Hadbeen fracturezones. Modelling of theWAS and gravity data (three profiles across and three along the margin)gives insights into the first- and second-order structures. (1) Continental thinning is abrupt(15–20 km thinning across 50–100 km distance). It is accommodated by several tilted blocks.(2) The ocean–continent transition (OCT) is narrow (15 km wide). The velocity modellingprovides indications on its geometry: oceanic-type upper-crust (4.5 km s−1) and continentaltypelower crust (>6.5 km s−1). (3) The thickness of the oceanic crust decreases from West(10 km) to the East (5.5 km). This pattern is probably linked to a variation of magma supplyalong the nascent slow-spreading ridge axis. (4) A 5 km thick intermediate velocity body (7.6to 7.8 kms−1) exists at the crust-mantle interface below the thinned margin, the OCT and theoceanic crust. We interpret it as an underplated mafic body, or partly intruded mafic materialemplaced during a ‘post-rift’ event, according to the presence of a young volcano evidencedby heat-flow measurement (Encens-Flux survey) and multichannel seismic reflection (Encenssurvey). We propose that the non-volcanic passive margin is affected by post-rift volcanismsuggesting that post-rift melting anomalies may influence the late evolution of non-volcanicpassive margins

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“…Further east in the same area, 070°E faults (faults named C) that are recognized onshore continue offshore [d' Acremont, 2002;d'Acremont et al, 2005] with a strike of about 110°E Figure 2. Geological and structural map of the Dhofar (Oman) northeastern margin of the Gulf of Aden, from geological maps, field and satellite data (this study), and from Roger et al [1989] and Platel and Roger [1989]. Note the various strikes of faults, their undulating trace, and the complex geometry of the basins.…”

Section: Fault and Synrift Basin Geometriesmentioning

confidence: 99%

Fault reactivation and rift localization: Northeastern Gulf of Aden margin

et al. 2006

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The Gulf of Aden and the Sheba spreading ridge (Gulf of Aden) forms the southern boundary of the Arabian Plate. Its orientation (075°E) and its kinematics (about 030°E divergence) are interpreted as the result of an oblique rifting. In this contribution, a field study in the northeastern Gulf of Aden allows us to confirm the Oligo‐Miocene synrift directions of extension and to precise the normal fault network geometry. The synrift extensions are 020°E and 160°E (possibly in this chronological order); the normal faults strike 070°E, 090°E, and 110°E. The results show that some characteristics are consistent with oblique rifting analogue models, while some others are not. Especially, fault reactivation of Mesozoic structures is shown to have occurred significantly at the beginning and during rifting. These data are therefore compared to analogue models of oblique reactivation, and this comparison demonstrates that fault reactivation played a key role during the early stage of the Gulf of Aden rifting. Finally, scenarios of the lithospheric evolution during the eastern Gulf of Aden opening (preexisting weaknesses in the lithosphere or not) are discussed to better constrain the deformation history of the northern margin. Especially, we show that rift localization processes may imply stress rotations through time.

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Donnees nouvelles sur la stratigraphie et l'histoire geologique du Dhofar (sultanat d'Oman)

Cited by 85 publications

References 0 publications

From rifting to spreading in the eastern Gulf of Aden: a geophysical survey of a young oceanic basin from margin to margin

From rifting to spreading in the eastern Gulf of Aden: a geophysical survey of a young oceanic basin from margin to margin

The crustal structure of the north-eastern Gulf of Aden continental margin: insights from wide-angle seismic data

Fault reactivation and rift localization: Northeastern Gulf of Aden margin

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