Folds and faults mapped affecting the seafloor accommodate the present-day
convergence between the Eurasian and African plates. This convergence is oblique
with NW-SE shortening and orthogonal extension, and the related faults have a high
level of seismic activity that determines the NNE-SSW seismicity band crossing the
Alboran Sea. Regional tectonics is considered a controlling factor on fluid flows are
related to diapirs and mud volcanoes mapped in the WAB.
The morphosedimentary features reflect the way sediment has been transported
and deposited. Their near surface sediments indicate that sedimentation is mainly
siliciclastic with locally mixed sediments (terrigenous-carbonate) in the eastern
Iberian sector (Almería margin). Five types of sedimentological facies have been
identified in the Pleistocene-Holocene near surface record: nearshore, prodelta,
contourites, turbidites, and mass-flow deposits. The proximal continental margin is
dominated by coastal and fluvio-marine sedimentary processes that have been acting
since the last glacial sea-level change. Features found on the outer continental
margin (relict nearshore facies and wave-cut terraces) mainly formed during the
last sea-level rise and today are relict. Modern features (prodeltas, IPWs, and
bedforms) generally occur on the inner-middle shelf and have been deposited during
the present-day highstand (6500 years BP to present). The distal continental margin
is mainly dominated by marine sedimentary processes, with the action of alongslope
bottom currents of the AW and MWs being responsible for the ubiquity of contourite
sedimentation. On the other hand, channelised downslope turbidity flows and related
flows responsible for building the turbidite systems, were dominant during the
glacial periods when the sea-level and continental sediment sources were closer to,
or below, the shelf-break. The occurrence of landslides is relatively more important
on the active structural seamounts and seems to be the consequence of the interplay
of several triggering factors, including over-steepening, seismicity, under consolidation due to overpressure by interstitial fluids, stratigraphy, and high sedimentation
rates.
The seafloor morphology of the Alboran Sea facilitates an assessment of the main
potential geological hazards. These hazards can be categorised into three main
groups related to: (1) tectonic processes; (2) slope instability processes; and (3) bottom currents. The main potential hazards are a consequence of seismicity and
landslides, which can also trigger destructive tsunamis. The Alboran Sea is an
excellent area in which to demonstrate the association of geoscience and habitats,
leading to a better understanding of the total ecosystem.
Acknowledgements This work was supported by the following Spanish projects: INCRISIS,
DAMAGE (CGL2016-80687-R AEI/FEDER), FAUCES (CTM2015-65461-C2-1-R) and
ALSSOMAR S2S (CTM2017-88237-P), RNM 148 and RNM 328—Junta de Andalucía,
MONCARAL and RIGEL projects (Instituto Español de Oceanografía) and Marlboro cruises.
Likewise, this study was supported by the French program Actions Marges and the EUROFLEETS
program-SARAS cruise (FP7/2007-2013; 228344). The Secretaria General de Pesca (Spain)
yielded the bathymetric data from the northern part of the Alboran Sea. IHS-Kingdom Suite
educational license.
196
G. Ercilla et al.
convergence between the Eurasian and African plates. This convergence is oblique
with NW-SE shortening and orthogonal extension, and the related faults have a high
level of seismic activity that determines the NNE-SSW seismicity band crossing the
Alboran Sea. Regional tectonics is considered a controlling factor on fluid flows are
related to diapirs and mud volcanoes mapped in the WAB.
The morphosedimentary features reflect the way sediment has been transported
and deposited. Their near surface sediments indicate that sedimentation is mainly
siliciclastic with locally mixed sediments (terrigenous-carbonate) in the eastern
Iberian sector (Almería margin). Five types of sedimentological facies have been
identified in the Pleistocene-Holocene near surface record: nearshore, prodelta,
contourites, turbidites, and mass-flow deposits. The proximal continental margin is
dominated by coastal and fluvio-marine sedimentary processes that have been acting
since the last glacial sea-level change. Features found on the outer continental
margin (relict nearshore facies and wave-cut terraces) mainly formed during the
last sea-level rise and today are relict. Modern features (prodeltas, IPWs, and
bedforms) generally occur on the inner-middle shelf and have been deposited during
the present-day highstand (6500 years BP to present). The distal continental margin
is mainly dominated by marine sedimentary processes, with the action of alongslope
bottom currents of the AW and MWs being responsible for the ubiquity of contourite
sedimentation. On the other hand, channelised downslope turbidity flows and related
flows responsible for building the turbidite systems, were dominant during the
glacial periods when the sea-level and continental sediment sources were closer to,
or below, the shelf-break. The occurrence of landslides is relatively more important
on the active structural seamounts and seems to be the consequence of the interplay
of several triggering factors, including over-steepening, seismicity, under consolidation due to overpressure by interstitial fluids, stratigraphy, and high sedimentation
rates.
The seafloor morphology of the Alboran Sea facilitates an assessment of the main
potential geological hazards. These hazards can be categorised into three main
groups related to: (1) tectonic processes; (2) slope instability processes; and (3) bottom currents. The main potential hazards are a consequence of seismicity and
landslides, which can also trigger destructive tsunamis. The Alboran Sea is an
excellent area in which to demonstrate the association of geoscience and habitats,
leading to a better understanding of the total ecosystem.
Acknowledgements This work was supported by the following Spanish projects: INCRISIS,
DAMAGE (CGL2016-80687-R AEI/FEDER), FAUCES (CTM2015-65461-C2-1-R) and
ALSSOMAR S2S (CTM2017-88237-P), RNM 148 and RNM 328—Junta de Andalucía,
MONCARAL and RIGEL projects (Instituto Español de Oceanografía) and Marlboro cruises.
Likewise, this study was supported by the French program Actions Marges and the EUROFLEETS
program-SARAS cruise (FP7/2007-2013; 228344). The Secretaria General de Pesca (Spain)
yielded the bathymetric data from the northern part of the Alboran Sea. IHS-Kingdom Suite
educational license.
196
G. Ercilla et al.