HR: 10:35h
AN: OS51D-02 INVITED     [PDF]
TI: Sediment transport processes across crenulated clinoforms on the western Adriatic prograding mud wedge
AU: * Puig, P
EM: ppuig@icm.csic.es
AF: Institut de Ciencies del Mar (CSIC), Passeig Maritim de la Barceloneta 37-49, Barcelona, 08003 Spain
AU: Guillen, J
EM: jorge@icm.csic.es
AF: Institut de Ciencies del Mar (CSIC), Passeig Maritim de la Barceloneta 37-49, Barcelona, 08003 Spain
AU: Palanques, A
EM: albertp@icm.csic.es
AF: Institut de Ciencies del Mar (CSIC), Passeig Maritim de la Barceloneta 37-49, Barcelona, 08003 Spain
AB: Sea-floor crenulations of complex and uncertain origin characterize large portions of the late Holocene prograding mud wedge in several sectors of the Apennine shelf. Sediment failure has been postulated as the most plausible mechanism for their formation, although their maintenance through time seems to be related to different sediment accumulation rates in the flat and steep flanks. In order to establish relationships between active sediment dynamics, cross-shelf transport and sediment accumulation in these crenulated fields, as part of the EuroSTRATAFORM program, and in combination with the Po and Apennine Sediment Transport and Accumulation (PASTA) study, a tripod and a mooring were deployed off the Pescara River during autumn and winter 2002-2003, in a region characterized by a crenulated clinoform. The tripod was placed at 20 m water depth, close to the clinoform roll-over point, and the mooring was located at 50 m depth, in the foreset region. Several sediment-resuspension events were recorded at the tripod site, mainly related to Bora and Sirocco storms, during which current and wave shear stresses reached similar values. Sediment transport around the roll-over point was predominantly towards the SE, following direction of the coastal current and the bathymetry, but showing a significant offshore component that was intensified during storm events. Currents at the mooring site were also directed to the SE. In mid-waters they were clearly aligned with the local bathymetry, whereas near the bottom they had an important and continuous offshore component. This predominant offshore current behavior near the bottom seems to be associated with an intense bottom Ekman transport, which will enhance the suspended sediment transport from the topset down the foreset region and contribute to the development of the clinoform feature. In addition, activity of near-inertial waves was also recorded by the moored current meters and temperature sensors. During periods characterized by a strong near-inertial signal (17 h), increases of the water turbidity clearly coincided with the offshore direction of the cross-shelf velocity component and with strong temperature fluctuations through the water column. During these events, velocities in the cross-shelf and along-shelf components were similar, which suggest that near-inertial internal waves also contribute to the offshore transport of suspended sediment across the crenulated clinoforms. Further analysis about the role of near-inertial internal waves in the sediment dynamics of the study area will provide insights for understanding if this mechanism could have created and/or maintained the crenulated clinoforms that that extends along the Apennine shelf.
DE: 3022 Marine sediments--processes and transport
DE: 3045 Seafloor morphology and bottom photography
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting