Implications of Sediment Dynamics in Mass Transport along the Pianosa Ridge (Northern Tyrrhenian Sea)

摘要

The Pianosa Ridge forms the eastern flank of the Corsica Trough in the Northern Tyrrhenian Sea: it is the site of preferential accumulation of contourites and Mass Transport Deposits (MTDs). Along the Pianosa Ridge, 11 MTDs with a total volume of 6.5 km~3 were identified. These MTDs are distributed in three areas: (A) one small MTD associated to canyon flank destabilisation in the northern part of the study area; (B) six intermediate size MTDs in the central area; (C) four MTDs of larger size (up to 2.62 km~3) to the south, including the Pianosa Slump, which is the most recent MTD in this area (aged at 42-50 kyr BP) and analysed in more detail. The main factor controlling the formation of MTDs in areas A and B seems to be steep slopes associated to erosion and heterogeneous sedimentation caused by bottom currents, respectively. In contrast, multiple factors may control slope instability in the zone where the largest MTDs took place (area C): the incision generated by contour currents, the presence of coarser layers in contourite drifts that may accumulate gas and the location of normal faults near the headwall.