Ductile extensional shear zones in the lower crust of a passive margin

Abstract : We describe and interpret an unpublished set of ION Geophysical seismic reflection profile showing strong organized seismic reflectors at the base of the continental crust of the Uruguayan volcanic rifted margin. We distinguish two main groups of reflectors in the lowermost continental crust. A first group, at depths ranging from 32 km below the continent to 16 km in the continent–ocean transition, comprises reflectors continuous over tens of kilometers, peculiarly visible near the mantle–crust boundary. A second group of reflectors dipping toward the ESE (oceanward) is widely distributed in the lower crust. These reflectors are slightly curved and tend to merge and become sub-parallel with the first group of reflectors. Together they draw the pattern of thick shallow-dipping top-to-the continent shear zones affecting the lower continental crust. Such sense of shear is also consistent with the continentward dip of the normal faults that control the deposition of the thick syn-tectonic volcanic formations (SDR). A major portion of the continental crust behaved in a ductile manner and recorded a component of top-to-the continent penetrative simple shear during rifting indicative of a lateral movement between the upper crust and the mantle.
Type de document :
Article dans une revue
Earth and Planetary Science Letters, Elsevier, 2015, 431, pp.1-7. 〈10.1016/j.epsl.2015.08.038〉
Liste complète des métadonnées

Littérature citée [27 références]  Voir  Masquer  Télécharger

https://hal-insu.archives-ouvertes.fr/insu-01239900
Contributeur : Nathalie Pothier <>
Soumis le : vendredi 17 novembre 2017 - 11:03:44
Dernière modification le : vendredi 17 novembre 2017 - 11:23:06

Fichier

Clerc-EPSL-2015.pdf
Fichiers produits par l'(les) auteur(s)

Identifiants

Collections

Citation

Camille Clerc, Laurent Jolivet, Jean-Claude Ringenbach. Ductile extensional shear zones in the lower crust of a passive margin. Earth and Planetary Science Letters, Elsevier, 2015, 431, pp.1-7. 〈10.1016/j.epsl.2015.08.038〉. 〈insu-01239900〉

Partager

Métriques

Consultations de la notice

157

Téléchargements de fichiers

10