Mass Transport Complexes from Contourite and Shelf-Edge Deposits Along the South-Western Adriatic Margin (Italy)

摘要

Seismic data and multi-beam bathymetry reveal the occurrence of several exposed or shallowly buried Mass Transport Complexes (MTCs) in the South-Western Adriatic margin (SWAM), which represents the outer sector of the Albanides-Dinarides foreland basin. MTCs are spatially diffused along the SWAM and characterized by high variability in size, morphology and internal geometry. MTCs are derived from the mobilisation of both contourite drift deposits and shelf-margin progradational deposits. The most prominent MTC of the SWAM is the Gondola Slide (GS), a large, deep-seated (～250 m) MTC located near the Gondola-Dauno fault zone (GDFZ), involving around 30 km~3 of shelf and slope sediments. In the northern sector of the margin, the Vieste Slide (VS) affects a low gradient upper slope sector, which is extensively dominated by contourite drifts and sediment waves. Seismic correlation shows that the first and main failure events of GS and VS were contemporaneous and impacted the entire margin (more than 2,000 km~2), and probably were trigger by large earthquake, while later events in both GS and VS appear more localised and asynchronous indicating, probably, slope readjustments governed by local stratigraphic factors.