Morphological and seismostratigraphic evidence of Quaternary mass transport deposits in the North Ionian Sea: the Taranto landslide complex (TLC)

The Taranto Landslide Complex (TLC) is a large submarine landslide area located along the continental margin of the Puglia Region, in the Gulf of Taranto (North Ionian Sea), between 200 and 800m water depth. Based on very high-resolution multibeam data, a morphological analysis was performed by measuring different physical and spatial parameters (i.e., surface, headwall height and length, slope in the source area, and blocks in the accumulation zone). In addition, we use nine high-resolution sub-bottom CHIRP profiles to reconstruct the stratigraphic architecture. The main results show five phases of Quaternary mass transport deposits (MTDs) in the study area. The oldest to the youngest are MTD1, with a volume of about 0.032 km3 and an area of about 4 km2; MTD2, which is the largest of the identified deposits, covering an area of ~26 km2 and having an estimated volume of ~0.35 km3; and MTD3 and MTD4, with volumes of about 0.033 km3 and 0.035 km3 and an area of 7 km2 and 5 km2, respectively. The final submarine landslide is represented by MTD5, which has a volume of 0.02 km3. The deposits are internally characterized by chaotic acoustic facies with reflectors with moderate amplitude and laterally continuous in time, showing likely erosive characteristics defined as “bounding surfaces”. The main transport direction of the MTDs is from north/northeast to south/southwest. This represents the trend of the continental slope, but there is also slope failure evidence coming from west/ northwest to east/southeast (MTD5). The correlation between topographic and seismo-stratigraphic features allows the documentation of the characteristics, distributions, sources, and the triggering mechanisms of the Late Quaternary MTDs in the area. We suggest that still the unknown trigger mechanisms could be based on the performed analysis, related to the anomalously high sedimentation rates and/or sea level fluctuation.