composition. Textural analysis was performed using settling-tube techniques for the
coarse-grained fraction (<50μm) and Sedigraph 5000D techniques for the silt and
clay fractions (<50μm). Total carbonate content was determined using a Bernard
calcimeter. The sedimentary structures were examined based on digital images of the
split cores. The sand fraction composition was examined using a binocular microscope. For the hydrographic analysis, the CTD dataset was analysed with the Ocean
Data View (ODV) software using T/S diagrams, as well as N-S and E-W transect of
the key properties of the water masses. In addition, the ADCP data (Ercilla et al.
2016) also allowed an analysis of the variation in the E and N components of the
water flow with depth and the variation in the backscatter intensity of these components along the vessel track.
6.4 Physiography
Four physiographic domains have been defined in the Alboran Sea: continental
shelf, continental slope, base of slope, and basins (Fig. 6.3a).
The continental shelf extends down to a depth of 90–115 m on the Iberian margin
and 100–150 m on the North African margin. It is characterised by an abrupt outer
limit, with the exception of the easternmost African shelf, which has a poorly defined
ramp shape. The continental slopes of both margins are irregular: the Iberian margin
ranges from 10 to 83 km wide, and the African margin is 10–105 km wide, extending
to depths of up to 945 m in the west and 2294 m in the east (Fig. 6.3a). The
continental slopes also have intraslope basins, including the Southern Alboran
Basin (1180 m deep), and the Motril Basin (920 m deep). The other intraslope
basins are the Al-Hoceima Valley (470 m deep), the Habibas Basin (928 m deep),
and the Pytheas Basin (880 m deep) (Fig. 6.3a). The base of slope is defined in the
Alboran Sea by an important decrease in slope gradients (<2–0.8
). This province is
locally defined on the western Iberian margin at water depths of between 600 and
945 m, and on the eastern Iberian margin at water depths of between 1400 and
1850 m. The basin domain comprises the Eastern Alboran Basin (2294 m deep); the
Western Alboran Basin (1510 m deep); the northeast/southwest-oriented Alboran
Trough (up to 1800 m deep); and the Yusuf Basin (up to 2340 m deep) (Fig. 6.3a).
6.5 Geomorphology
6.5.1 Shelf Features
Most of the observations on shelf geomorphology refer to the northern shelf of the
Alboran Sea. However, recent studies have provided geomorphological descriptions
of limited sectors of the southern shelf (e.g. Lafosse et al. 2018). The main
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G. Ercilla et al.
coarse-grained fraction (<50μm) and Sedigraph 5000D techniques for the silt and
clay fractions (<50μm). Total carbonate content was determined using a Bernard
calcimeter. The sedimentary structures were examined based on digital images of the
split cores. The sand fraction composition was examined using a binocular microscope. For the hydrographic analysis, the CTD dataset was analysed with the Ocean
Data View (ODV) software using T/S diagrams, as well as N-S and E-W transect of
the key properties of the water masses. In addition, the ADCP data (Ercilla et al.
2016) also allowed an analysis of the variation in the E and N components of the
water flow with depth and the variation in the backscatter intensity of these components along the vessel track.
6.4 Physiography
Four physiographic domains have been defined in the Alboran Sea: continental
shelf, continental slope, base of slope, and basins (Fig. 6.3a).
The continental shelf extends down to a depth of 90–115 m on the Iberian margin
and 100–150 m on the North African margin. It is characterised by an abrupt outer
limit, with the exception of the easternmost African shelf, which has a poorly defined
ramp shape. The continental slopes of both margins are irregular: the Iberian margin
ranges from 10 to 83 km wide, and the African margin is 10–105 km wide, extending
to depths of up to 945 m in the west and 2294 m in the east (Fig. 6.3a). The
continental slopes also have intraslope basins, including the Southern Alboran
Basin (1180 m deep), and the Motril Basin (920 m deep). The other intraslope
basins are the Al-Hoceima Valley (470 m deep), the Habibas Basin (928 m deep),
and the Pytheas Basin (880 m deep) (Fig. 6.3a). The base of slope is defined in the
Alboran Sea by an important decrease in slope gradients (<2–0.8
). This province is
locally defined on the western Iberian margin at water depths of between 600 and
945 m, and on the eastern Iberian margin at water depths of between 1400 and
1850 m. The basin domain comprises the Eastern Alboran Basin (2294 m deep); the
Western Alboran Basin (1510 m deep); the northeast/southwest-oriented Alboran
Trough (up to 1800 m deep); and the Yusuf Basin (up to 2340 m deep) (Fig. 6.3a).
6.5 Geomorphology
6.5.1 Shelf Features
Most of the observations on shelf geomorphology refer to the northern shelf of the
Alboran Sea. However, recent studies have provided geomorphological descriptions
of limited sectors of the southern shelf (e.g. Lafosse et al. 2018). The main
164
G. Ercilla et al.