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Genre/Form: | Thèses et écrits académiques |
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Material Type: | Document, Thesis/dissertation, Internet resource |
Document Type: | Internet Resource, Computer File |
All Authors / Contributors: |
Youssef Biari; Frauke Klingelhoefer; Daniel Aslanian; Mohamed Sahabi; Jacques Déverchère; Sylvie Leroy, geÌophysicienne).; Mohamad Hafid; Khalid Mehdi; James Albert Austin; Université de Bretagne occidentale.; Université Chouaïb Doukkali (El Jadida, Maroc).; École doctorale Sciences de la mer (Plouzané, Finistère).; Laboratoire de géophysique et géodynamique (Plouzané, Finistère). |
OCLC Number: | 1076543766 |
Notes: | Thèse soutenue en co-tutelle. Titre provenant de l'écran-titre. |
Description: | 1 online resource |
Responsibility: | Youssef Biari ; sous la direction de Frauke Klingelhoefer et de Daniel Aslanian et de Mohamed Sahabi. |
Abstract:
The NE American margin represents one of the best studied margins in the world, it was the subject of several scientific programs. In comparison, the conjugate NW African margin remains fairly unknown, only two deep seismic cruises were acquired: the SISMAR cruise (2001) offshore the Meseta and the DAKHLA cruise (2002) offshore the Sahara. The deep structure of the Canadian margin is known due to the SMART wide-angle seismic profiles 1, 2 and 3. The first objective of the MIRROR project was to acquire combined wide-angle and deep reflection seismic data offshore a segment conjugate to the SMART-1 profile. The comparison between the homologous segments of these two margins aimed to better understand the opening mechanism of the Central Atlantic Ocean. A comparison between Sismar, Dakhla and Mirror models shows that the continental crust is thicker in the north and thins toward the south. The width of the transition zone is narrower south and Sismar profiles are located on a sedimentary basin placed on a very thinned continental crust. Comparing the Mirror profile with that of the Canadian conjugate margin (Smart 1) shows that the thickness, the structure of the continental crust and the thinning is very similar. However, zones of exhumed and serpentinized mantle were imaged along the Canadian profile that have no conjugate on the African margin. Moreover, the thickness of the oceanic crust is variable with 8 km on the African side and only 3-4 km on the Canadian margin. Several hypotheses have been proposed to explain this difference (a) an age difference between the two types of crust (b) thickening associated with the passage of the Canary hotspot (c) an asymmetric accretion or (d) an accretion at slow to ultra-slow speading centers.
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