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Active Sedimentation and Tectonics in the South Alboran Sea: Preliminary Results of the Marlboro and SARAS Surveys

Elia d'Acremont, Christian Gorini, Belen Alonso, Abdellah Ammar, Mohammed El Abbassi, Marc de Batist, Silvia Ceramicola, Damien Do Couto, Gemma Ercilla, Marc-Andre Gutscher, Sylvie Leroy, Bernard Mercier de Lépinay, Nieves Lopez-Gonzalez, Sébastien Migeon, Bouchta El Moumni, Jeffrey Poort, Alain Rabaute, Pascal Le Roy, Jeroen Smit, Abdelilah Tahayt, Gabriel Teurquety, Juan-Tomas Vazquez, and Thomas Vandorpe

We present new multibeam and reflection seismic data from the Moroccan margin in the Alboran Sea that shows ongoing deformation along this margin. In 2011-2012 the MARLBORO-1, -2 and SARAS cruises acquired mid, high and ultra-high resolution seismic reflection, swath bathymetry and EK60 data as well as gravity cores (with Actions Marges and Eurofleets funding) which has allowed the imaging of sedimentary cover at different scales.

In the Alboran Sea, the thinned continental crust and the overlying sedimentary cover have been inverted due to the convergence between Eurasia and Africa. Strong tectonic activity during the Pliocene and Quaternary is indicated by syn-sedimentary infilling of a E-W, NE-SW oriented Plio-Quaternary basin, the presence of many associated scarps as well as mass-transport deposits and mud volcanoes. Active folding and faulting and associated fluid migration and mud volcanism are responsible for numerous failures and mass-transport deposits. Tofino bank consists in fact in two separated banks also interpreted as E-W active thrust-fold complexes with associated mud volcanoes activity.

The siliciclastic material, including the supply of the Morrocan rivers are reworked by bottom currents that have strongly eroded the morphological structures produced by tectonism and/or volcanic activity. Since the Pliocene, most of the depositional systems in this area are contourites that evolved synchronously with growth-faulting. Tectonic inversion is recorded since the Tortonian with an acceleration of uplift and compression evidenced since the Messinian.

Offshore Al Hoceima Bay a network of active normal faults and strike-slip faults have been imaged in the bathymetric and high-resolution seismic reflection data. Two distinct sets of faults are observed, one set striking north-south through the Al Hoceima Bay and the second west of Al Hoceima Cap, striking northeast-southwest. These active faults were responsible for the strong and devastating Al Hoceima earthquakes in 1994 and 2004.

AAPG Search and Discovery Article #90161©2013 AAPG European Regional Conference, Barcelona, Spain, 8-10 April 2013