The Hitherto Unknown Parameters in the Architecture Model of the Alboran Sea fans: the Contouritic Processes

Gemma Ercilla, Belen Alonso, Carmen Juan, Ferran Estrada, F. Javier Hernandez-Molina, David Casas, Estafania Llave, Marcel.li Farran, Marga García, Christian Gorini, Elia D'Acremont, Juan-Tomas Vazquez, and Bouchta El Moumni

The Alboran Sea is characterized by at least 8 turbiditic fans in the western and central Spanish margin and none in the Moroccan margin (19 to 53 km long). The development of these fans interrupts the lateral continuity of terraced plastered and sheeted drifts making up mostly the continental slope and base of slope-to-basin respectively. The fan sedimentary model is similar for all, being characterized by a feeder canyon -locally also gulliescrossing the slope that directly mouths into a lobe with aggrading leveed channels. The lobes comprise: a) a single linear to low sinuousity feeder channel, or b) a single linear to low sinuousity channel linked downslope to distributary sinuous channels. There is also a turbidite system where the feeder system comprises gullies (6 km long) linked downdip to amalgamated lobe deposits. The architecture and dimensions of these systems suggest their sedimentary model ranges between sandy and mixed sand-mud fans, and they describe a continuum between both end-member types from west to east. The oceanographic gateway context of the Alboran Sea between the Atlantic and Mediterranean waters, and its related contouritic processes, are the main factors responsible of the architecture model of these fans as well as their lack in the Moroccan margin. When fine sediment arrives to the sea, it is pirated by the Atlantic water mass (0 to 250 m depth) and distributed by the two anticyclonic gyres that define its circulation. Fine sediment becomes part of a complex circulation system mainly formed by three underlying water masses, the Winter Intermediate Water (100 to 300 m) and Levantine Intermediate Water (200 to 600 m) in the Spanish margin, and the Western Mediterranean Deep Water (> 275 m) mainly in the Moroccan margin. Their contouritic processes contribute to the outbuilding of the margin and infilling of the basins. Likiwese, the pirate of fine sediment is locally so important that may have avoided the formation of canyons in front of large rives in the Spanish margin and their lack in the Moroccan margin.

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