The age of this striking channel is constrained by the eroded sediments and
erosional surfaces. The channel clearly cuts the regional erosional surface as well
as the chaotic sediments related to the MSC sea level drop, during coeval salt
deposition in other areas of the Mediterranean Sea. In the easternmost Alboran
Basin, the channel also incised the lattermost deposits of the MSC (UU), therefore
indicating an age between the latest Messinian and Zanclean. As a result of the
Zanclean Flooding, and postdating the MSC UU, several chaotic lenticular bodies
developed atop the Zanclean channel margins, probably constituting a rare example
of megaflood deposits coeval to those described for the Alboran Sea (Periáñez et al.
2019) and the nearby sill of the Strait of Sicily (Micallef et al. 2018).
What caused the opening of the Strait of Gibraltar? This is an unanswered
question. Certain hypotheses evoke tectonic control, sea level changes, or retrogressive fluvial erosion, yet the most plausible cause is a combination of tectonics and
retrogressive river erosion (Blanc 2002; Loget and Van Den Driessche 2006; GarciaCastellanos and Villaseñor 2011).
5.7 Pliocene-Quaternary
The Pliocene-Quaternary deformation of the Alboran Sea is evidenced by the change
from a mostly compressional regime (Campos et al. 1992; Maldonado et al. 1992;
Woodside and Maldonado 1992; Rodriguez-Fernandez and Martin-Penela 1993;
Estrada et al. 1997) and by a shift in the orientation of the convergence vector
between the Eurasian and African plates, from NW-SE to WNW-ESE (Mazzoli and
Helman 1994; Rosenbaum et al. 2002b; Merkouriev and DeMets 2008; MartínezGarcía et al. 2013). It contributed to the reactivation, propagation, and uplift of the
NE-SW oriented structures (Estrada et al. 1997; Comas and Soto 1999; MartínezGarcía et al. 2013). To accommodate this convergence, indentation tectonics developed in the central Alboran Sea gave rise to two conjugated sets of dextral
WNW-ESE and sinistral NE-SW to NNE-SSW faults, while in the same context
ENE-WSW-oriented folds and antiforms developed (Estrada et al. 2018).
Three major shortening phases have been defined to characterize the PlioceneQuaternary tectonic history of the Alboran Sea (Martínez-García et al. 2013):
(a) earliest Pliocene (ca. 5.33–4.57 Ma), mainly deforming the Alboran Ridge; b)
late Pliocene (ca. 3.28–2.59 Ma), uplifting the Alboran Ridge until closing the
gateway that had connected the SAB and WAB; and c) Pleistocene (ca.
1.81–1.19) (e.g., Estrada et al. 1997; Martínez-García et al. 2013), entailing further
deformation and uplift of the Alboran Ridge, deformation in the Yusuf Lineament
(Martínez-García et al. 2013; Estrada et al. 2018), and northward propagation of the
Al-Idrissi Fault zone (d’Acremont et al. 2014; Estrada et al. 2018).
The Alboran Basin narrowed considerably during the Pliocene due to the emergence of onshore sub-basins and the progressive uplifting of the Alboran Ridge as a
result of the first two major phases of shortening (Martínez-García et al. 2013).
Basement flexure along Pliocene caused a general deepening of sedimentary units
5 A Geological History for the Alboran Sea Region
137
erosional surfaces. The channel clearly cuts the regional erosional surface as well
as the chaotic sediments related to the MSC sea level drop, during coeval salt
deposition in other areas of the Mediterranean Sea. In the easternmost Alboran
Basin, the channel also incised the lattermost deposits of the MSC (UU), therefore
indicating an age between the latest Messinian and Zanclean. As a result of the
Zanclean Flooding, and postdating the MSC UU, several chaotic lenticular bodies
developed atop the Zanclean channel margins, probably constituting a rare example
of megaflood deposits coeval to those described for the Alboran Sea (Periáñez et al.
2019) and the nearby sill of the Strait of Sicily (Micallef et al. 2018).
What caused the opening of the Strait of Gibraltar? This is an unanswered
question. Certain hypotheses evoke tectonic control, sea level changes, or retrogressive fluvial erosion, yet the most plausible cause is a combination of tectonics and
retrogressive river erosion (Blanc 2002; Loget and Van Den Driessche 2006; GarciaCastellanos and Villaseñor 2011).
5.7 Pliocene-Quaternary
The Pliocene-Quaternary deformation of the Alboran Sea is evidenced by the change
from a mostly compressional regime (Campos et al. 1992; Maldonado et al. 1992;
Woodside and Maldonado 1992; Rodriguez-Fernandez and Martin-Penela 1993;
Estrada et al. 1997) and by a shift in the orientation of the convergence vector
between the Eurasian and African plates, from NW-SE to WNW-ESE (Mazzoli and
Helman 1994; Rosenbaum et al. 2002b; Merkouriev and DeMets 2008; MartínezGarcía et al. 2013). It contributed to the reactivation, propagation, and uplift of the
NE-SW oriented structures (Estrada et al. 1997; Comas and Soto 1999; MartínezGarcía et al. 2013). To accommodate this convergence, indentation tectonics developed in the central Alboran Sea gave rise to two conjugated sets of dextral
WNW-ESE and sinistral NE-SW to NNE-SSW faults, while in the same context
ENE-WSW-oriented folds and antiforms developed (Estrada et al. 2018).
Three major shortening phases have been defined to characterize the PlioceneQuaternary tectonic history of the Alboran Sea (Martínez-García et al. 2013):
(a) earliest Pliocene (ca. 5.33–4.57 Ma), mainly deforming the Alboran Ridge; b)
late Pliocene (ca. 3.28–2.59 Ma), uplifting the Alboran Ridge until closing the
gateway that had connected the SAB and WAB; and c) Pleistocene (ca.
1.81–1.19) (e.g., Estrada et al. 1997; Martínez-García et al. 2013), entailing further
deformation and uplift of the Alboran Ridge, deformation in the Yusuf Lineament
(Martínez-García et al. 2013; Estrada et al. 2018), and northward propagation of the
Al-Idrissi Fault zone (d’Acremont et al. 2014; Estrada et al. 2018).
The Alboran Basin narrowed considerably during the Pliocene due to the emergence of onshore sub-basins and the progressive uplifting of the Alboran Ridge as a
result of the first two major phases of shortening (Martínez-García et al. 2013).
Basement flexure along Pliocene caused a general deepening of sedimentary units
5 A Geological History for the Alboran Sea Region
137