Flip-flop detachment tectonics at nascent passive margins in SE Afar

Laurent Geoffroy (1) , Bernard Le Gall (1) , Mohammed Daoud (2) , Mohamed Jalludin (2)

1 LDO - Domaines Océaniques
2 CERD - Centre d’Etudes et de Recherche de Djibouti

We propose a two-stage tectonic evolution of SE Afar in Djibouti leading to the complex development of highly asymmetric conjugate margins. From c. 8.5 to c. 2 Ma, an early mafic crust developed, associated in the upper crust with synmagmatic growth faults dipping dominantly to the SW. After an erosional stage, a new detachment fault system developed from c. 2 Ma with an opposite sense of motion (i.e. to the NE), during an amagmatic extensional event. In the Asal area, break-up occurred after c. 0.8 Ma along the footwall of an active secondary detachment fault rooted at depth above the lithospheric necking zone. This evolution suggests that flip-flop detachment tectonics is developed during extension at passive margins, in connection with the dynamics of the melting mantle and the associated magma plumbing of the crust.

Domains: Tectonics; Global Changes

Laurent Geoffroy, Bernard Le Gall, Mohammed Daoud, Mohamed Jalludin. Flip-flop detachment tectonics at nascent passive margins in SE Afar. Journal of the Geological Society of London, 2014, 171 (5), pp.689-694. ⟨10.1144/jgs2013-135⟩. ⟨insu-01022271⟩