HR: 11:05h
AN: OS51D-04 INVITED     [PDF]
TI: Shaping of the Southern Adriatic Continental Margin Through Widespread Mass Wasting and Bottom Currents
AU: * Trincardi, F
EM: fabio.trincardi@bo.ismar.cnr.it
AF: ISMAR-CNR, Sezione Geologia Marina, Via Gobetti 101, Bologna, 40129 Italy
AU: Cattaneo, A
EM: antonio.cattaneo@bo.ismar.cnr.it
AF: ISMAR-CNR, Sezione Geologia Marina, Via Gobetti 101, Bologna, 40129 Italy
AU: Correggiari, A
EM: anna.correggiari@bo.ismar.cnr.it
AF: ISMAR-CNR, Sezione Geologia Marina, Via Gobetti 101, Bologna, 40129 Italy
AU: Verdicchio, G
EM: giuseppe.verdicchio@bo.ismar.cnr.it
AF: ISMAR-CNR, Sezione Geologia Marina, Via Gobetti 101, Bologna, 40129 Italy
AU: TOBI, T
EM: dgm@soc.soton.ac.uk
AF: Challenger Division for Seafloor Processes SOC, Empress Dock, Southampton, SO14 3ZH Italy
AB: New TOBI seafloor images and VHR Chirp sonar profiles reveal widespread collapsing of the South Adriatic continental slope including: multiple overlapping slide scars affecting more than 100 km of Pleistocene regressive shelf-margin deposits below the shelf edge, extensive blocky slides on the lower slope (block sizes up to 200 x 500 m), and a basin wide acoustically-transparent deposit up to 40 m thick, buried under a late-Pleistocene-Holocene mud section, in water depths greater than 1000 m. Lateral variations in internal geometry and seafloor morphology likely reflects along margin differences in sediment composition and thickness of the mass-transport deposits and variable run outs (up to 40 km). Preliminary correlation to published cores in the area indicates that the main mass transport deposit reached the basin floor during the Last Glacial Maximum, but younger failures of smaller size may have affected the slope in more recent times. The new data show that the entire slope area is swept by bottom currents generating furrowed areas up to several tens of km$^{2}$ in extent, moats on the downdrift side of seafloor irregularities (slide blocks) and preferential sediment deposition on the inferred updrift side, and growth of upslope-migrating sediment waves. In particular, two fields of sediment waves can be mapped in water depths of 400-600 and 1000 m. The former may reflect the activity of the Levantine Intermediate Waters, while the latter may be linked to the downslope flow of the Northern Adriatic Dense Waters. Future work will focus on the definition of intervals of growth vs quiescence of the sediment waves, their possible relation to paleoceanographic reconfigurations, and their interplay with seafloor irregularities dictated by slope instability. A smaller-scale possibly comparable interaction of seafloor morphology generated by sediment deformation and differential deposition of muddy deposits on the shelf emphasizes the importance of bottom-hugging currents in the semi-enclosed Adriatic basin in a wide range of water depths.
DE: 3025 Marine seismics (0935)
DE: 4219 Continental shelf processes
DE: 4255 Numerical modeling
DE: 4558 Sediment transport
DE: 4863 Sedimentation
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting