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Article Dans Une Revue Geophysical Journal International Année : 2015

Crustal structure and gravity anomalies beneath the Rif, northern Morocco: implications for the current tectonics of the Alboran region

Carole Petit
Bruno Scalabrino
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Michel Corsini
Mickael Bonnin
Adrien Romagny
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Résumé

We analyse Bouguer anomaly data and previously published Moho depths estimated from receiver functions in order to determine the amount of isostatic compensation or uncompensa-tion of the Rif topography in northern Morocco. We use Moho depth variations extracted from receiver function analyses to predict synthetic Bouguer anomalies that are then compared to observed Bouguer anomaly. We find that Moho depth variations due to isostatic compensation of topographic and/or intracrustal loads do not match Moho depth estimates obtained from receiver function analyses. The isostatic misfit map evidences excess crustal root as large as 10 km in the western part of the study area, whereas a 'missing' crustal root of ∼5 km appears east of 4.3 • E. This excess root/missing topography correlates with the presence of a dense mantle lid, the noticeable southwestward drift of the Western Rif area, and with a current surface uplift. We propose that a delaminated mantle lid progressively detaching westward or southwestward from the overlying crust is responsible for viscous flow of the ductile lower crust beneath the Rif area. This gives rise to isostatic uplift and westward drift due to viscous coupling at the upper/lower crust boundary. At the same time, the presence of this dense sinking mantle lid causes a negative dynamic topography, which explains why the observed topography is too low compared to the crustal thickness.
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Dates et versions

hal-02546672 , version 1 (18-04-2020)

Identifiants

Citer

Carole Petit, Laetitia Le Pourhiet, Bruno Scalabrino, Michel Corsini, Mickael Bonnin, et al.. Crustal structure and gravity anomalies beneath the Rif, northern Morocco: implications for the current tectonics of the Alboran region. Geophysical Journal International, 2015, 202, pp.640 - 652. ⟨10.1093/gji/ggv169⟩. ⟨hal-02546672⟩
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