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Article Dans Une Revue Journal of Geophysical Research : Solid Earth Année : 2015

Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco

Histoire post-rift de la marge passive orientale de l'océan Atlantique central: Aperçus depuis la région saharienne du Sud-Maroc

Résumé

The passive margin of South Morocco is a low-elevated passive margin. It constitutes one of the oldest margins of the Atlantic Ocean, with an Early Jurassic breakup, and little geological data are available concerning its postrift reactivation so far. We investigated the postrift thermal history of the onshore part of the margin with low-temperature thermochronology on apatite crystals. Fission track and (U-Th-Sm)/He ages we obtained are significantly younger than the breakup (~190 Ma). Fission track ages range from 107 ± 8 to 175 ± 16 Ma, with mean track lengths from 10.7 ± 0.3 to 12.5 ± 0.2 μm. (U-Th-Sm)/He ages range from 14 ± 1 to 185 ± 15 Ma. Using inverse modeling of low-temperature thermochronological data, we demonstrate that the South Moroccan continental margin underwent a complex postrift history with at least two burial and exhumation phases. The first exhumation event occurred during Late Jurassic/Early Cretaceous, and we attribute this to mantle dynamics rather than to intrinsic rifting-related processes such as flexural rebound. The second event, from Late Cretaceous to early Paleogene, might record the onset of Africa/Europe convergence. We show a remarkably common behavior of the whole Moroccan passive margin during its early postrift evolution. The present-day differences result from a segmentation of the margin domains due to the Africa/Europe convergence. Finally we propose that varying retained strengths during rifting and also the specific crustal/lithospheric geometry of stretching explain the difference between the topographical expressions on the continental African margin compared to its American counterpart.

Domaines

Géochimie
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Dates et versions

hal-03951492 , version 1 (23-01-2023)

Identifiants

Citer

Rémi Leprêtre, Yves Missenard, Jocelyn Barbarand, Cécile Gautheron, Omar Saddiqi, et al.. Postrift history of the eastern central Atlantic passive margin: Insights from the Saharan region of South Morocco. Journal of Geophysical Research : Solid Earth, 2015, 120 (6), pp.4645-4666. ⟨10.1002/2014JB011549⟩. ⟨hal-03951492⟩
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