Sediment dynamics and post-glacial evolution of the continental shelf around the Blanes submarine canyon head (NW Mediterranean).

摘要: Abstract The Blanes submarine canyon (BC) deeply incises the Catalan continental shelf in NW Mediterranean Sea. As a consequence of closeness (only 4 km) its head to coastline and mouth Tordera River, has direct influence on dispersal system as it collects large amounts sediment, mainly during high-energy events. Multibeam bathymetry, backscatter imagery very-high resolution seismic reflection profiles have allowed characterizing morphology around head, also identifying sediment sources transport pathways into canyon. morphological data been used reconstruct evolution last sea-level transgression so that current understanding shelf-to-canyon exchanges through time could be improved. surrounding BC consists both depositional erosional or non-depositional areas. Depositional areas display prominent bodies, generally smooth bathymetry variable backscatter. These include: (i) an area modern coarse-grained accumulation comprises inner shelf; (ii) fine-grained sedimentation middle offshore Tossa de Mar; (iii) depleted covers most outer west head. Erosional rough topography high backscatter, occur primarily east where arrival river-fed inputs is very small. In agreement with this pattern, north likely main source To north, pattern extends from suggesting remobilization off-shelf export fines. Additionally, relict near-shore sand bodies developed over Barcelona extend rim constitute coarse sediment. High-energy processes, namely river floods coastal storms, are controls river-shelf-canyon exchange. River increase delivery terrigenous particles system. Storms, east, remobilize temporarily accumulated towards finer fractions preferentially removed lag normally left floor. Exceptionally, strong storms remove drive them Processes like dense water cascading, which much more intense canyons BC, Northern Current contribute suspended far distant northern sources. During post-glacial had margin, interrupted by isolating shelves south, named La Planassa shelves, respectively.