Seismic stratigraphy of upper Quaternary shallow-water contourite drifts in the Gulf of Taranto (Ionian Sea, southern Italy)

Abstract

The occurrence of articulated seafloor morphology over continental shelf-upper slope environments, may result in a significant change in the patterns and intensity of basin-scale thermohaline circulation during eustatic sealevel fluctuations. These changes may cause, in turn, erosion, deposition and/or transport of sediments at the seafloor, to form shallow-water contourite drifts. Here we investigate this process in the NW sector of the Gulf of Taranto (Ionian Sea) during and following the Last Glacial Maximum (LGM), by integrating multibeam bathymetric data, ultra-high resolution seismic-reflection data and gravity core data. Sea level fall caused subaerial exposure of the summit of the Amendolara Bank, forming a short-lived island off the eastern coast of Calabria, and also creating a narrow passageway between the island and the northern Calabria mainland. Integrated seismic-stratigraphic data show that Upper Quaternary shallow-water contourite drifts and associated erosional features locally formed both around the flanks of the Amendolara Bank (AMBK), and the continental shelf and upper slope off the Amendolara village. Contourite drifts are bounded at the bottom and at the top by two major unconformities, indicating that the formation of the sediments drifts occurred between the onset of the LGM and the GS-1/Younger Dryas event. The stratal architecture suggests the occurrence of various types of contourite deposits, mostly represented by: a) Axial and lateral channel-patch drifts, and channel-related drifts along the incision to the NE of the AMBK; b) Sheeted drifts along the northeastern slope of the AMBK; c) Elongated drifts along the continental shelf and upper slope off the coast of Amendolara village. Erosional features also developed on the south-eastern flank of the AMBK, where the Levantine Intermediate Water flows from the central Ionian Sea towards the Gulf of Taranto, until the present-day. Both processes and timing responsible for erosion of the seafloor and the formation of sediment drifts in the Gulf of Taranto may be similar to that occurred in the Tyrrhenian margins during the Late Quaternary.