Submarine Valleys Research Articles

Models of Deltaic and Inner Continental Shelf Landform Evolution

The morphology of passive continental shelves is dictated by the input of sediments from rivers and their redistribution by waves, currents, and gravity-driven flows. The pathways followed by sediments sculpt a landscape whose diversity is rarely matched on Earth's surface. Sediments are released to the shelf from triangularly shaped, elongated, and dendritic deltas. Barrier islands rise from gently sloping areas, tidal channels dissect flats and saltmarshes, fine sediments form broad convex deposits, and shallow submarine valleys convey sediments and water to the deep ocean. This morphological diversity is based on two main building elements: water and sediments. Fluxes of water and sediments are particularly suitable to be modeled with numerical methods based on the continuum hypothesis and hydrodynamics theory. In recent years, a series of models have been developed to explore and understand the formation of shelf landforms from the dynamics of sediment transport. Herein we present an overview of the most recent results on the modeling of deltaic and inner-shelf morphodynamics.

Seismostratigraphy and sedimentation environment on the shelf and continental slope of Peter the Great Bay (Sea of Japan)

The results of a single channel seismic reflection survey and of a micropaleontological examination of diatom remains in bottom sediment samples on the shelf and continental slope of the Peter the Great Bay area are presented. The composition and age of the sedimentary layer were studied using integrated seismic, micropaleontological and geological data. The continental slope was formed not later than at the beginning of the Early Miocene. The slope is covered with Middle Miocene-Pliocene sediments. The sedimentary thickness on most of the slope is 0.2–0.4 s. The maximum thickness (0.8–1.0 s) is observed within the areas of submarine canyons and valleys. The thickness of the Early Miocene-Pliocene sediments on the shelf is 0.2–0.4 s. On the shelf break and in a southwest-trending trough of the acoustic basement, it increases up to 1.0 s. Two uncomformities were identified in the sediments of the shelf area. The proposed age of the upper uncomformity is 10.0–8.5 My B.P.; it represents the result of a global sea level fall. The age of the lower uncomformity is unknown.

The sea-floor morphology of a Mediterranean shelf fed by small rivers, northern Alboran Sea margin

Depositional geometries and distribution patterns of shelf sediment wedges mainly derived from small rivers located in the northern margin of the Alboran Sea, Western Mediterranean Basin, are reported in this study, in order to understand: (1) their generation under particular physiographic and climatic conditions of river basins; (2) the interaction of shallow-water wedges with submarine valleys. A high amount of data has been used in this study, including river discharge and wave climate data, multibeam bathymetry, high-resolution seismic profiles and surficial sediment samples. The eastern shelf of the study area comprises the prodeltaic wedge off the Guadalfeo River and its eastward continuation, interrupted by the deeply indented Carchuna Canyon head. In contrast, the western shelf receives the contributions of a smaller river, the Verde River, whose associated prodeltaic wedge is limited to the inner shelf. Morphological features of both prodeltas are similar and differ from other Mediterranean prodeltaic bodies, resembling fan deltas. Those similarities include very steep foresets and bottomsets, very shallow and close to the coast offlap break, coarse sediment composition, lobate shape and common occurrence of crenulated sea floor. All these features point out to an origin linked to the activity of high-density sediment flows, rapid sedimentation and limited lateral redistribution. Those processes are favoured by the existence of an abrupt onshore physiography, a regional climate with a marked seasonality that conditioned torrential fluvial regimes and high availability of loose sand and gravel. Shelf sediment by-pass is a likely process during the Holocene in the eastern shelf, as suggested by the identification of two types of submarine valleys: (1) numerous gullies occur from the distal toe of the Guadalfeo River prodelta to the slope; (2) submarine canyon heads affect to the Holocene sedimentary wedge in the eastern sector of the study area. In the western shelf, however, the influence of shelf sedimentation processes on deeper domains is minimal, due to shelf widening, prevalence of relict features and absence of submarine valleys.

The western part of the Gulf of Cadiz: contour currents and turbidity currents interactions

Recent multibeam bathymetry and acoustic imagery data provide a new understanding of the morphology of the western part of the Gulf of Cadiz. The gulf is under the influence of a strong current, the Mediterranean Outflow Water (MOW). This current is at the origin of the construction of the giant Contourite Depositional System. Canyons and valleys with erosive flanks are observed. Only the Portimao Canyon is presently connected to the continental shelf. Channels occur on the continental shelf but are presently disconnected from the deeper network of channels and valleys. Slumps are localized in steep slope areas. They are caused by oversteepening and overloading, sometimes probably associated with earthquake activity. Slumps transform sharply into turbidity currents, depositing turbidites on the floor of deep valleys. Interaction of the MOW and gravity currents is suggested by the filling of the incisions located on the drifts below the present seafloor, the shifting of valleys and canyons in the direction of the MOW flow inducing an unusual phenomenon of capture of submarine valleys.

Vertical structure of time-dependent currents in a mid-ocean ridge axial valley

Velocity measurements with high vertical resolution, and a two-dimensional linear quasianalytic model for subinertial oscillatory flows, are used to analyze the vertical structure of flow in the axial valley at Endeavour Segment, Juan de Fuca Ridge. At a site away from hydrothermal vents, observed semidiurnal flows are independent of depth, rectilinear and parallel to the valley axis, while subinertial flows are intensified and re-aligned along-valley toward the bottom. This behavior is consistent with solutions from the model, which show attenuation of subinertial across-valley flow with depth. This cross-flow attenuation is most pronounced for valleys with widths less than the internal Rossby radius of deformation. Reduction of across-valley flow with depth results in a weakened Coriolis force that cannot fully balance the along-valley pressure-gradient force. The resulting force imbalance yields a directly accelerated bottom-intensified along-valley flow. The importance of this physical process in other submarine valleys depends on their geometry, stratification and latitude. If active, this mechanism provides a dynamic background environment for the axial valley to which hydrothermal venting would add complexity. The strong vertical shears and spiraling flows observed within the axial valley for diurnal tidal and lower-frequency flows have important implications in the transport of hydrothermal vent fluid and the dispersal of larvae of vent organisms by bottom currents.

Diapycnal mixing associated with an overflow in a deep submarine canyon

Abstract In order to close the global overturning circulation the buoyancy loss to the atmosphere associated with the formation of deep and bottom water at high latitudes must be balanced by buoyancy gain elsewhere. In case of water that is not in contact with the atmosphere except in its formation region the required buoyancy gain is accomplished primarily by diapycnal mixing. Recent observations suggest that a significant portion of the diapycnal buoyancy fluxes in the abyss is associated with overflows in submarine valleys or canyons, especially on the flanks of slow-spreading mid-ocean ridges. In the present study, hydrographic and velocity data from an overflow across a sill rising 1000 m above the floor of the rift valley of the Mid-Atlantic Ridge near 36°N were used to infer the associated diapycnal mixing. The cross-sill density gradients are characterized by a vertical dipole, with an upper layer of streamwise density increase overlying a lower layer where the density decreases along the flow. This is qualitatively consistent with the effects of diapycnal mixing transferring buoyancy from the upper into the lower layer. Hydrographic and velocity profiles provide evidence for strong mixing associated with the overflow across the sill: in addition to thick layers that are susceptible to shear instability, there are numerous density overturns indicating a spatially averaged diffusivity of order 10 - 2 m 2 s - 1 . Inversions of the density equation reveal that the cross-sill gradients can be accounted for either by adiabatic vertical advection or by vertical eddy diffusion, although the adiabatic solutions are considered energetically implausible because they require upwelling in the layer of cross-sill density increase. Eddy-diffusive solutions, both with and without adiabatic downwelling, are characterized by diffusivity profiles attaining local maxima of order 10 - 2 m 2 s - 1 ≈ 250 m above the sill depth. The vertical structure of the inversion-derived diffusivities is consistent with the Thorpe-scale based estimates and with observations from overflows in major ocean passages, which also are often characterized by local diffusivity maxima of order 10 - 2 m 2 s - 1 a few 100 m above sill depth. Combining the diffusivity profiles near the sill with budget-derived bulk estimates for 150 km of rift valley implies that ≈ 50 % of the mixing in the rift valley is associated with overflows, while the remainder is caused by other processes, including the breaking of tidally forced internal waves.

Construction of the Pyreneo-Languedocian Sedimentary Ridge and associated sediment waves in the deep western Gulf of Lions (Western Mediterranean)

Migrating sediment waves have been recognized in a wide range of marine settings, including turbidite levees adjacent to submarine canyons and valleys. The Pyreneo-Languedocian Sedimentary Ridge (PLSR), located in the Gulf of Lions (North-western Mediterranean), appears similar to such a levee. In an attempt to understand the construction of both the PLSR and associated sediment waves, several scale-studies were done. The data include high and medium resolution seismic reflection profiles and cores collected both on upslope and downslope sides of two successive waves. At a regional scale, the situation of the PLSR was strongly influenced by Pliocene salt tectonics movements that resulted in a basin at the mouth of the Catalano-Languedocian canyons. Later, salt tectonics were chiefly inactive during Quaternary and waves do not result of an extensive superficial tectonic activity. At the scale of the PLSR, the construction occurred during the Quaternary and is divided in three stages recognized on the basis of waves' geometry, sediment supplies changes and spillover source variations. Common sediment wave cross-sections have been identified and suggest a turbidite or a gravity-flow origin. Sedimentological, lithostratigraphical and biostratigraphical studies focus on the last sea-level rise and high stand period. The results support the sediment-wave initiation and the occurrence of sand transfers even during the more recent period. Sand layers and high sedimentation rates characterize the deposits on upstream flanks. Lower rates of deposition correspond with downstream flanks.

Late Cenozoic depositional history of the Danish North Sea Basin: implications for the petroleum systems in the Kraka, Halfdan, Siri and Nini fields

The Central Graben area was filled with a thick pile of sediments during the Middle Miocene – Quaternary, corresponding to a period of 15Ma. As hydrocarbon expulsion from the most prolific source rock, the Upper Jurassic Bo Member, was initiated only 20 Ma BP and still occurs today, the Middle Miocene – Quaternary evolution is important. In the Middle Miocene, the Central Graben area was covered by a sea with water depth of 500–700 m. During the Late Miocene (Tortonian), the basin was successively filled by prograding slope and deltaic sediments from the northeast. The progradational infill resulted in local tilting of the substratum due to the loading effect of the deposits. In the latest Late Miocene (Messinian), the main input of sediments occurred from the south, as illustrated by a thick onlapping succession of upper Messinian sediments. Pliocene sedimentation was characterized by regular infill from the east within a shelf to shallow marine depositional environment. Following the Miocene and Pliocene, the North Sea Basin tilted due to strong uplift of the Fennoscandian shield and increased subsidence and sedimentation rates within the Central Graben area. This further complicated the maturation of the source rock, migration pathways and accumulation of hydrocarbons. The consequence of this complex burial history is exemplified by the Kraka and Halfdan fields. The Kraka Field has a large down-flank oil accumulation, which is the result of a porosity anomaly resulting from an early invasion of oil in this position before the late tilting of the North Sea Basin. The history of the non-structural accumulation of the Halfdan Field can be readily modelled; it constituted a simple four-way dip closure during the Late Miocene when peak oil migration occurred. The Quaternary tilting of the North Sea Basin due to uplift of the Fennoscandian Shield and strong subsidence of the Central Graben area resulted in a distinct gradient favouring long-distance migration of hydrocarbons. The occurrence of viable migration routes, especially within Paleocene sand layers, has resulted in long-distance migration of oil into the Siri submarine valley system. The most northern indication of hydrocarbons has been recognized as far as 75km from the source area. Long-distance migration of hydrocarbons is also indicated by direct hydrocarbon indications (DHIs) throughout the Cenozoic succession in the Danish North Sea. DHIs are particularly prominent above known hydrocarbon accumulations in the Central Graben. This indicates pronounced vertical migration, for instance along active faults, above these structures.

Understanding continent‐ocean sediment transfer

Submarine canyons are narrow but deep submarine valleys that extend for hundreds of meters. They represent the most impressive structures that shape the present morphology of passive continental margins. They can occur off the mouth of rivers: the Tagus, Zaire, Amazon, and Orinoco in the Atlantic; the Indus in the Indian Ocean; and the Var, Rhone, and Ebro in the Mediterranean. Some are at times disconnected from any stream mouth such as the Nazare canyon, off Portugal, despite the fact that it is close to the coast. Some were connected to a river mouth during lowstands of sea level, such as the Wilmington canyon in the northwest Atlantic, or the Blackmud canyon in the northeast Atlantic.

Salt tectonics, a controlling factor on the development of the Marseilles and Grand-Rhone sedimentary ridges, Gulf of Lions, western Mediterranean Sea

Abstract The Marseilles (also called Marseilles/Planier) and Grand Rhone sedimentary ridges, offshore the Gulf of Lions, western Mediterranean Sea, are generated by sediment spillover funnelled by the Marseilles and Grand-Rhone canyons, respectively. We show that the Marseilles and Grand-Rhone canyon directions are tectonically conditioned by Plio-Quaternary salt-induced sea-floor relief. Overburden extension in the area created an assemblage of listric faults running parallel to the strike of the continental margin. This salt-induced topography resulted in accentuated fault scarps impacting the sea-floor morphology and forcing submarine valleys to deflect to the east. Gravity-induced extension equally influenced the morphological pattern of the valley overbanking deposits. Sediment spillover occurred on both flanks of the canyons, but because active faulting generated space accommodation for overflow deposits, it inhibited the development of typical levee morphology along the canyons' left flanks. To cite this article: A.T. dos Reis, C. R. Geoscience 336 (2004).

Present morphology and depositional architecture of a sandy confined submarine system: the Golo turbidite system (eastern margin of Corsica)

Abstract The modern sandy Golo turbidite system (500 km 2 ) is located in a confined basin on the eastern margin of Corsica. The Golo turbidite system is fed by a single river, which supplies coarse sand derived from active weathering of the neighbouring mountains. The late Quaternary deposits have been imaged using a closely spaced grid of 1000 km of sparker seismic-reflection profiles (line spacing close to 1.6 km, vertical resolution of 2m). The turbidite system is composed of four non-coalescent fans that were at times active simultaneously and of two small deposits onto the slope. The resulting sedimentation pattern is characterized by stacked turbidite deposits. At a regional scale, there is a continuum of fan morphologies and geometries from south to north. The use of both seismic and sedimentary facies, together with mapped seismic geometry of sedimentary bodies, allowed definition of four architectural elements: (1) submarine valley (canyon and gully), (2) sandy channel, (3) muddy levee, and (4) sandy lobe. Some of these architectural elements can be recognized at a scale that is comparable to outcrop examples. Features such as progressive lateral migration and avulsion, or complex longitudinal evolution (progradation and retrogradation), can also be accurately described. Despite the active tectonics along the studied margin, the main variations in sedimentation appear to be controlled by eustatic changes, pre-existing seafloor topography, and sediment source characteristics. The general pattern of sedimentation is controlled by the influence of a confining slope, leading to the predominance of aggradation and to specific morphology and architecture of sedimentary bodies.

Multiple terraces within the deep incised Zaire Valley (ZaïAngo Project): are they confined levees?

Abstract Terraces have been frequently observed and described along turbidite valleys. Many interpretations have been aimed at determining the origin of these structures, including a tectonic origin, succession of infilling and incision processes, channel-wall slumps, or inner levee aggradation. The Zaire submarine valley presents a complex structure with multiple terraces bordering a deep incised meandering thalweg. The detailed analysis of the morphology, the seismic structure and the recent sedimentation (in cores) along the Zaire upper-fan valley show that terraces are inner levees confined within the incised valley. Many terraces correspond to the infilling of abandoned meanders, and aggrade by deposition of turbidite sequences due to current overflows. The major process affecting the initiation and the development of terraces inside the valley is the vertical incision of the thalweg, simultaneously with meander migration.

Direct observation of intense turbidity current activity in the Zaire submarine valley at 4000 m water depth

A large turbidity current was detected in the Zaire submarine valley at 4000 m water depth. Current meters, turbidimeter and sediment trap deployed on a mooring located in the channel axis, although they were damaged, recorded the signature of a very high energy event. An average velocity of more than 121 cm s −1 was measured 150 m above the channel floor. Coarse sand and plant debris were collected at 40 m height. The turbidity current clearly overflowed the edges of the valley as demonstrated by the large quantity of turbiditic material (464 mg organic carbon m −2 d −1) found in the sediment trap moored 13 km south from the channel axis.

Morphology and Geologic Implications of Penghu Channel off southwest Taiwan

Penghu Channel shows submarine valley morphology characterized by relatively shallow and wide elongate depression with gently sloping sides and a continuous bottom gradient. The possibility of being a river valley of the Penghu Channel during Late Pleistocene can not be ruled out. But, modern currents completely overprint the signature of inherited paleo-geo-morphology of a river valley. At present, Penghu Channel is considered as a scour furrow of probably erosion origin, mainly by northward tidal currents. It serves as a sediment pathway transporting shelf sediment alongshore and northward on the tide-dominated Taiwan Strait shelf. Penghu channel together with Yunchang Ridge to the north may be considered parts of a modern tidal erosion and deposition system. Bathymetric data indicate that Penghu Channel may not extend seaward into Penghu Canyon. The head and main course of Penghu Canyon are not aligned with Penghu Channel. They are two different undersea features, not a continuous sea valley. The hypothesis of an ancient Minchiang River flowing from China and extending southward to the sea through a sinuous valley on the exposed Taiwan Strait during Late Pleistocene is not supported by evidence of newly generated bathymetric chart and modern hydrodynamics.

Mid‐Palaeocene palaeogeography of the eastern North Sea basin: integrating geological evidence and 3D geodynamic modelling

ABSTRACTThe Mid‐Palaeocene palaeogeography of Denmark and the surrounding areas have been reconstructed on the basis of published geological data integrated with 3D geodynamic modelling. The use of numerical modelling enables quantitative testing of scenarios based on geological input alone and thus helps constrain likely palaeo‐water depths in areas where the geological data are inconclusive or incomplete.The interpretation of large‐scale erosional valleys and small‐scale circular depressions at the Mid‐Palaeocene Top Chalk surface in the Norwegian–Danish basin as either submarine or subaerial features is enigmatic and has strong implications for palaeogeographical reconstructions of the eastern North Sea basin.A 3D thermo‐mechanical model is employed in order to constrain the likely palaeo‐water depths of the eastern North Sea basin during the Palaeocene. The model treats the lithosphere as an elasto‐visco‐plastic continuum and models the lithospheric response to the regional stress field and thermal structure. The model includes the effects of sea‐level change, sedimentation and erosion, from the Mid Cretaceous to the present. Modelling results reproduce to first order geological data such as present sediment isopachs and palaeo‐water depths.It is concluded that the Mid Palaeocene water depths in the Norwegian–Danish basin were about 250 m. The erosional valleys and circular depressions at the top of the Upper Cretaceous‐Danian Chalk Group are thus interpreted to have formed in relatively deep water rather than due to subaerial exposure. Likely interpretations of the structures are therefore submarine valleys and pockmarks.

Variations of continental discharge pattern in space and time: implications from the Laptev Sea continental margin, Arctic Siberia

Variations in sediment input and distribution to the Laptev Sea continental margin during the Holocene and Termination I could be identified based on radiocarbon dated magnetic susceptibility logs and sediment thickness in high-resolution seismic profiles. Magnetic susceptibility of surface samples reveals an increased input of magnetic grains to the Laptev Sea deriving from the Anabar and Khatanga river catchments. Exposed magnetite schists and volcanic rocks of the Anabar shield and Putoran Plateau, respectively, function as major source of magnetic material. The distribution of magnetic susceptibility in association with the thickness of the Holocene sediments indicates bottom-current induced sediment transport guided by major submarine valleys on the Laptev Sea shelf. The sites of filled paleoriver channels identified in the seismic profiles suggest that during the Late Weichselian sea-level lowstand river runoff continued through four of the major valleys on the exposed Laptev Sea shelf. The sediments at the top of the lowstand deposits in front of the Anabar-Khatanga valley, represented in the seismic profiles by prograding deltas, are characterized by outstandingly high magnetic susceptibility values. Radiocarbon datings approximate the deposition of these high magnetic sediments between 10 and 13.4 ka. It is suggested that this increased input of magnetic material is related to the deglaciation of the Anabar shield and the Putoran Plateau and thus support their glaciation during marine isotope stage (MIS) 2.

Active deformation and volcanism offshore Campi Flegrei, Italy: new data from high-resolution seismic reflection profiles

The interpretation of high-resolution seismic reflection profiles permitted the identification of many geologic features in the inner shelf of Pozzuoli Bay. This area corresponds to the offshore of Campi Flegrei: a classically active volcanic area that experienced earthquakes and meter-scale vertical ground uplift before the 1538 Monte Nuovo eruption and in the period from 1970 to 1985. The detected undersea features include two small debris flows that are located in a submarine valley in the western part of Pozzuoli Bay. They may be the result of a pyroclastic flow and a pyroclastic surge that entered the sea. The younger debris flow in the uppermost marine deposits of Pozzuoli Bay formed during the 1538 Monte Nuovo eruption, and the older debris flow during the 3.8 ka-old Averno eruption. Other features detected by our survey are an undersea 8 m-high and 1 km-wide cryptodome, corresponding to a near-surface intrusion, located off Pozzuoli, that warped post-4 ka marine deposits. The interpretation of the cryptodome is based on seismic facies analysis, deformation geometry and correspondence to a magnetic high. It is suggested that this undersea dome formed during the uplift phases associated with the 1538 Monte Nuovo eruption and the two more recent bradyseismic crises of 1970–1972 and 1982–1984. Surface-breaking faults (with maximum vertical offset of 1 m) were recognized in very shallow waters near the coast of Pozzuoli. It is suggested that some of these faults were active during the 1982–1984 bradyseismic earthquake sequence.

Ripple cross-laminated sediments on the East Antarctic Shelf: evidence for episodic bottom water production during the Holocene?

Abstract Biosiliceous sediments sampled from a submarine valley system on the continental shelf of East Antarctica contain intervals of ripple cross-lamination interspersed with massively bedded units. Based on radiocarbon dates from one core collected on the Mac.Robertson Shelf, the most intensely cross-laminated sediments were deposited between 6 and 3.5 kyr BP, with isolated cross-laminae deposited at other times in the Holocene. The cross-laminated sediments are interpreted here as a signal of episodic density currents flowing across the outer shelf, which result from the formation of high salinity shelf water (HSSW). This HSSW is formed in winter by brine rejection during sea ice formation and by the exchange and cooling of upwelled saline slope water, and it contributes to the bottom water produced along the continental margin of Antarctica. If this interpretation of the cross-laminae is correct, then bottom water formation and export from the East Antarctic shelf has exhibited temporal, and probably also spatial, variability throughout the Holocene. Such variability would have implications for oceanographers attempting to quantify Antarctic bottom water production rates based only on present day observations.

Imaging submarine channels in the western Nile Delta and interpreting their paleohydraulic characteristics from 3-D seismic

Predicting sand distribution and reservoir presence is a major exploration risk in the Nile Delta offshore Egypt. However, integrating state-of-the-art technologies including 3-D seismic reflection surveys, seismic attributes, amplitude extractions, and coherency techniques can reduce this risk through recognition and more accurate mapping of submarine valleys and channel complexes. In addition, identification of sediment input points and pathways may result in more accurate interpretations of sand distribution patterns.

Sedimentation processes in a tectonically active environment: the Kerkyra–Kefalonia submarine valley system (NE Ionian Sea)

The Kerkyra–Kefalonia valley system is the northwestern extension of the Hellenic arc–trench system, representing the collision zone of the Apulian Platform and the Hellenides. The system is distinguished by two different physiographic regions: the northern part, U-shaped, and oriented NNW–SSE, with relatively gentle slopes and a wide floor; and the southern part, oriented NE–SW, V-shaped, and with much steeper side walls and a narrow floor. Both parts are formed tectonically, with the former coinciding with a collision zone, and the latter being the morphometric expression of the Kefalonia strike–slip fault. Sediments recovered in the piston cores from the region consist of fine-grained material, deposited by a variety of sedimentation processes such as: gravity-driven mass movements, associated with seismic activity (i.e., slumping, sliding, debris flows, grain flows, turbidites–seismoturbidites); and, to a lesser extent, by hemipelagic deposition. Measured near-bed currents and their associated shear stresses indicate resuspension of the material, mainly within the northern part of the valley. Sub-bottom acoustic (seismic) profiling data reveal various sedimentary provinces, related to different mechanisms of sediment accumulation: (i) the eastern margin of the Apulian Platform with hemipelagic sedimentation, together with possible advection of suspensates from the Adriatic, in response localised to seabed erosion; (ii) the western Hellenic margin, with down-slope episodic sliding and slumping, induced primarily by earthquake activity, together with an input from hemipelagic settling; (iii) the collision zone, coinciding with the northern part of the Kerkyra–Kefalonia valley system, with deposition mostly from resuspension, the occurrence of local mass gravity flows and the advection of some material from the north; and (iv) the Kefalonia strike–slip fault region, where mass gravity flows are the dominant mechanisms, related to erosion/deposition from resuspension. Overall sedimentation within the tectonically-active Kerkyra–Kefalonia valley system is characterised by the coupling of the mass gravity-driven flows, which are the predominant mechanisms, with the near-bed current regime related with resuspension phenomena and the advection of suspensates. These latter mechanisms is likely more pronounced during the winter period, when dense water masses formed in the Adriatic inflowing into the Ionian Sea.