Shelf-edge erosion, sediment failure and inception of Bari Canyon on the Southwestern Adriatic Margin (Central Mediterranean)

摘要

We investigate the impact of regional tectonic setting and sedimentary dynamics on the onset of Bari Canyon, the main sediment conduit on the Southwestern Adriatic Margin (SAM). Since the Middle Pleistocene, deposition on the SAM, a foreland basin relative to the Southern Apennines, was primarily controlled by glacio-eustatic cycles. However, a number of tectonic structures, active since the early Cenozoic, impacted on the stacking of progradational deposits and on the overall slope setting and stability along the SAM. Four depositional sequences accomplished the progradation of the shelf-margin between ca. 450 kyr BP and the Last Glacial Maximum lowstand (ca. 20 ka BP). These sequences are variably dissected by two large-scale erosional features on the upper slope: 1) Bari Canyon, and 2) Gondola Slide headscarp, further north. The shelf facing these two major erosional structures shows several, smaller-scale incisions that merge with the sequence boundaries between each of the four stacked depositional sequences. The distribution of these erosional features reflects the location of tectonic structures that are still active, suggesting that both the intense erosion and the sediment failure in these areas were enhanced by tectonic deformation. We define the age of these older episodes of shelf-edge erosion and mass wasting that were conducive to the inception of Bari Canyon as we know it today. Moreover, we envisage the following predisposing factors as responsible for the inception and subsequent evolution of Bari Canyon: a) long-term regional uplift and margin tilt, likely controlling the lateral variability in shelf width and shelf-slope profile; b) rapid margin progradation during the deposition of Middle-Late Pleistocene sequences; c) recent tectonic deformation resulting in gentle folds growing during the canyon evolution.