@article {LoIacono2010, title = {{Large-scale bedforms along a tideless outer shelf setting in the western Mediterranean}}, journal = {Continental Shelf Research}, volume = {30}, number = {17}, year = {2010}, month = {oct}, pages = {1802{\textendash}1813}, abstract = {High-resolution multibeam swath-bathymetry and sediment samples were collected across the outer shelf region of the Columbretes Islands (southern Ebro continental shelf, western Mediterranean Sea). Bathymetric data from the submerged part of the Columbretes volcanic system revealed the presence of three main relict sand bodies along the outer shelf, at 80-116. m depth range, above which asymmetric and slightly asymmetric large and very large 2D and 3D subaqueous dunes were observed. These bed features were recognized, mapped and quantified with the aim of evaluating their potential formation mechanisms in relation to the local hydrodynamic and morphologic settings of the area. Dunes range from 150 to 760. m in wavelength and from tens of centimeters to 3. m in height, and are among the longest ever recognized in an outer shelf region. These bedforms are mostly composed of medium-sized sandy sediments, presumably coming from the degraded relict sand bodies on top of which they have developed, mixed with fine fractions from the recent draping holocenic sediments. The orientation of the dunes is SSW, progressively turning W towards the southernmost sector of the area, following the trend of the shelf-edge. Contemporary hydrodynamic measurements at the Ebro continental shelf-edge show that recorded currents are insufficient to form the observed bedforms and that stronger currents are required for sediment mobilization and dune formation. Based on their morphology and orientation, it is proposed that these bedforms are produced by the action of the southward-flowing Liguro-Proven{\c c}al-Catalan (LPC) geostrophic current. The LPC probably reaches high near-bottom currents during energetic hydrodynamic events through interactions with the seafloor morphology of the study area. Subaqueous dunes are expected to be basically inactive features with respect to present-day processes, although they can be reactivated during high-energy events. The small $Δ$h/${\l}ambda$ ratio measured in the dune fields of the Columbretes shelf revealed that the dune heights fall below the values predicted by the Flemming (1988) global equation, as observed in other outer shelf settings also dominated by unidirectional flows. This may suggest a different morphodynamic character of large dunes formed on outer shelves in a micro-tidal regime. {\textcopyright} 2010 Elsevier Ltd.}, keywords = {Continental shelf, Geomorphology, Subaqueous dunes, Swath mapping, Western Mediterranean}, issn = {02784343}, doi = {10.1016/j.csr.2010.08.005}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77957596289\&partnerID=tZOtx3y1}, author = {Lo Iacono, Claudio and Guill{\'e}n, Jorge and Puig, Pere and Rib{\'o}, Marta and Ballesteros, Maria and Palanques, Albert and l{\'\i} Farr{\'a}n, Marcel and Acosta, Juan} } @article {LoIacono2008b, title = {{Environmental conditions for gravelly and pebbly dunes and sorted bedforms on a moderate-energy inner shelf (Marettimo Island, Italy, western Mediterranean)}}, journal = {Continental Shelf Research}, volume = {28}, number = {2}, year = {2008}, month = {feb}, pages = {245{\textendash}256}, abstract = {Side scan sonar records, sediment textural characteristics, and in-situ field observations were used to study gravelly and pebbly dunes and sorted bedforms on the inner shelf of Marettimo Island, along the northwestern Sicilian shelf. The dunes are composed of coarse sands, gravels and pebbles (D50: 2-16 mm), displaying a symmetrical shape with a wavelength in the range of 1-2.5 m and a height of 0.15-0.30 m. The bedforms are distributed in a patchy pattern in a depth range of 10-50 m, and are described for the first time on a Mediterranean inner shelf. Sorted bedforms are linear morphological features developed almost perpendicular to the coast in the eastern sector of the island between 15 and 50 m water depth. Bottom shear stresses required for sediment entrainment and the generation of the shallower dunes can be reached during strong storms (Hs=5-6 m; Tp=9-11 s), which are not common in the Mediterranean Sea. However, wave storm events recorded in the study area during the last 17 years are not able to generate the coarsest and deeper dunes, suggesting that the stirring mechanism for dune formation is associated with severe storms that have a recurrence interval of more than 17 years. The long-term stability of the coarse bedforms is supported by the permanence of sorted bedforms without significant morphological changes for long periods (>13 years). Therefore, it is shown that processes forming coarse bedforms can occur in tideless and moderate-energy settings like those of the Mediterranean continental shelves, although the morphological features are probably less dynamic and remain unaltered for longer periods than on higher-energy shelves. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.}, keywords = {Gravel dunes, Inner shelf, Italy, Marettimo Island, Mediterranean Sea, Sorted bedforms}, issn = {02784343}, doi = {10.1016/j.csr.2007.08.005}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-37849005401\&partnerID=tZOtx3y1}, author = {Lo Iacono, Claudio and Guill{\'e}n, Jorge} }