Contourite keys to decode the Alboran Sea sedimentary evolution during the Plio-Quaternary

Carmen Juan, Gemma Ercilla, Ferran Estrada, David Casas, Belen Alonso, Margarita Garcia, Marcel.li Farran, Desiree Palomino, Juan-Tomas Vazquez, Estafania Llave, F. Javier Hernandez-Molina, Teresa Medialdea, Christian Gorini, Elia D'Acremont, Elmoumni Bouchta, Bernard Gensous, Michel Tesson, Andres Maldonado, and Abdellah Ammar

Recent studies in the Alboran Sea have defined a new sedimentary model where the contourite deposits are the main sedimentary systems, being interrupted by fans and mass-movements deposits. In this work the contourite depositional systems have been mapped in three Plio-Quaternary key moments, governed by global changes in paleoclimatology and paleoceacography: Lower Pliocene Revolution –LPR- (4.2 M.y.), Base of Quaternary Discontinuity –BQD- (2.6 M.y.) and Middle Pleistocene Revolution –MPR- (0.92 M.y.).

In the LPR time the main contourite depositional features are plastered drifts near the Gibraltar Strait and sheeted drifts covering most of the basins. The contourite erosive features comprise channels in the deep basins, narrow terraces at the uppermost slope, and a steep erosive scarp as an abrupt transition from the slope to the basin in the Spanish margin. In the BQD time the plastered drifts become broader, so sheeted drifts are progressively confined to the deep basins. A wide confined drift is located at the center of the Western Alboran Basin. Channels still shape the deep basins. The erosive terraces become broader, and we find steep erosive scarps at the base of slope in both margins of the Western Basin. In the MPR time, larger plastered drifts occur on the slopes, and sheeted drifts cover the basins. Elongated separated drifts can be found at the base of most structural highs, and confined drifts at the Djibouti marginal shelf. Channels are now local features. The erosive terraces comprise tens of kilometers wide.

It is known that contourite deposits can act as a reservoir system and play an important role as seals. Their geometry, stratigraphy and growth patterns of the contourites in the Alboran Sea may reveal/help to characterize reservoir elements that can be used routinely in hydrocarbon industry. Likewise, their sedimentary evolution allows decoding the paleoceanography and paleoclimate of sedimentary basins.

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