Transgressive Architecture of Coastal Barrier Systems in the Ofanto Incised Valley and Its Surrounding Shelf in Response to Stepped Sea-Level Rise

Abstract

Coastal deposits/barriers react to sea-level rise through rollover or overstepping. Preserved coastal deposits/barriers allow us to examine coastal responses to sea-level rise, an important aspect within the context of climate change. This study identifies the Ofanto incised valley and examines the possible factors that caused the considerable difference in shape between this valley and adjacent valleys: the Carapelle and Cervaro incised valley and Manfredonia incised valley. In addition, this study assesses the response of transgressive units to stepped sea-level rise with a focus on the evolution of palaeo-barriers/shorelines on the continental shelf and within the infill of Ofanto incised valley. We identified the traces of two slowstands in sea-level rise: the first, short-lived at a centennial scale, interrupted Meltwater Pulse 1A; the second is referable to part of Bølling-Allerød and Younger Dryas. During these two slowstands, two barrier-shoreface/estuarine-backbarrier systems formed. Meltwater Pulse 1A and Meltwater Pulse 1B led to overstepping and partial preservation of these systems in the form of aligned topographic highs. The second slowstand gave rise to continuous landward backstepping of the coastal barrier system; during the following Meltwater Pulse 1B (MWP-1B), landward rollover of the coeval barrier/backbarrier system occurred.

Keywords

• coastal barrier
• continuous backstepping pattern
• incised valley
• sapropel S1
• stepped sea-level rise