wedges (Ercilla et al. 1992, 1994; Hernández-Molina et al. 1994, 1996; Chiocci et al.
1997; Chap. 6).
Although early studies mostly carried out along the Spanish margin concluded
that confined and unconfined downslope processes and hemipelagic settling have
played a dominant role in outbuilding the continental margins and infilling basins,
bottom currents recently came under the spotlight (Ercilla et al. 2002, 2016;
Palomino et al. 2011; Juan et al. 2016, 2020). The greater depth of Pliocene basins
favored the action of a strong, dense countercurrent in the WAB (as modeled by
Alhammoud et al. (2010), in a shallow sill situation), which helps explain the thick
Pliocene deposits as well as the broad sheeted and plastered drifts. The uplifting of
the Alboran Ridge would have weakened this dense countercurrent (Juan et al.
2016); hence, a circulation model conditioned by the complex topography could
be established. The Quaternary topography gave rise to a separation of light versus
dense water flows into small-scale branches, forming minor contourite features
within narrow passages and at the base of the seamounts (Juan et al. 2016). The
changes in the contourite systems have allowed to interpretate an increase in the flow
energy from the Pliocene to the Quaternary in this area (Juan et al. 2020). Furthermore, the scarcity of turbidite systems in the Morocco margin has been explained by
the action of water masses that produces dispersion of the sediments (Ercilla et al.
2019), and the reduction in the number of turbidite systems since the Pliocene and
decrease in their sizes could be also related to the enhanced of water mass action on
sediment transport (Juan et al. 2020).
5.8 Conclusions: Paleogeographic Implications
The evolution of the area between Africa and Iberia, the region where the Alboran
Sea is currently located, has successively been constrained since the Jurassic by the
movement of the African and Eurasian plates, by the intermediate role of the Iberian
plate, showing a certain independence from the main plates during a period of its
development, and by orogenic processes since de Late Cretaceous first in the
Ligurian Tethys oceanic basin and later in the Western Mediterranean oceanic
basin. Related to the last process, a lithospheric terrane now known as the Alboran
Domain collided with the continental margins of South Iberia and North Africa since
the Upper Oligocene. The westward drift of this domain during the Miocene
generated an extensional basin inside, characterized by a very stretched continental
lithosphere and significant magmatic activity in its central and eastern sectors, that
evolved to the current basin of the Alboran Sea after compression from the Late
Tortonian.
One crucial element of the geological evolution between Africa and Iberia is their
geographical location: at the point of connection of two oceanic basins, the
geodynamic plates evolution was responsible for the creation and destruction of
several ocean basins and their oceanographic gateways. Thus, tectonics controlled
5 A Geological History for the Alboran Sea Region
139
1997; Chap. 6).
Although early studies mostly carried out along the Spanish margin concluded
that confined and unconfined downslope processes and hemipelagic settling have
played a dominant role in outbuilding the continental margins and infilling basins,
bottom currents recently came under the spotlight (Ercilla et al. 2002, 2016;
Palomino et al. 2011; Juan et al. 2016, 2020). The greater depth of Pliocene basins
favored the action of a strong, dense countercurrent in the WAB (as modeled by
Alhammoud et al. (2010), in a shallow sill situation), which helps explain the thick
Pliocene deposits as well as the broad sheeted and plastered drifts. The uplifting of
the Alboran Ridge would have weakened this dense countercurrent (Juan et al.
2016); hence, a circulation model conditioned by the complex topography could
be established. The Quaternary topography gave rise to a separation of light versus
dense water flows into small-scale branches, forming minor contourite features
within narrow passages and at the base of the seamounts (Juan et al. 2016). The
changes in the contourite systems have allowed to interpretate an increase in the flow
energy from the Pliocene to the Quaternary in this area (Juan et al. 2020). Furthermore, the scarcity of turbidite systems in the Morocco margin has been explained by
the action of water masses that produces dispersion of the sediments (Ercilla et al.
2019), and the reduction in the number of turbidite systems since the Pliocene and
decrease in their sizes could be also related to the enhanced of water mass action on
sediment transport (Juan et al. 2020).
5.8 Conclusions: Paleogeographic Implications
The evolution of the area between Africa and Iberia, the region where the Alboran
Sea is currently located, has successively been constrained since the Jurassic by the
movement of the African and Eurasian plates, by the intermediate role of the Iberian
plate, showing a certain independence from the main plates during a period of its
development, and by orogenic processes since de Late Cretaceous first in the
Ligurian Tethys oceanic basin and later in the Western Mediterranean oceanic
basin. Related to the last process, a lithospheric terrane now known as the Alboran
Domain collided with the continental margins of South Iberia and North Africa since
the Upper Oligocene. The westward drift of this domain during the Miocene
generated an extensional basin inside, characterized by a very stretched continental
lithosphere and significant magmatic activity in its central and eastern sectors, that
evolved to the current basin of the Alboran Sea after compression from the Late
Tortonian.
One crucial element of the geological evolution between Africa and Iberia is their
geographical location: at the point of connection of two oceanic basins, the
geodynamic plates evolution was responsible for the creation and destruction of
several ocean basins and their oceanographic gateways. Thus, tectonics controlled
5 A Geological History for the Alboran Sea Region
139