Evolution of an incised valley system in the southern Adriatic Sea (Apulian margin): an onshore–offshore correlation

Abstract

Seismic surveys with sub‐bottom profiler were carried out in the Manfredonia Gulf in the southern Adriatic Sea. Here, a buried surface was recognized on which three valleys, located about 80 km from the shelf edge, were deeply incised. Beneath this surface, a pre‐upper Würm seismic unit (PW) was identified. Above, two seismic units were recognized: the transgressive system tract (TST) and highstand system tract (g2). On the basis of regional correlation with onshore and offshore data, these units and their boundaries were dated and correlated with phases of the last glacial–interglacial cycle. The incised valley system was attributed to the Marine Isotopic Stage (MIS) 2. The TST and g2 units fill the valleys and were attributed to the post‐glacial sea‐level rise and highstand. The incised valleys are anomalous with respect to published models; despite having many characteristics that would have limited the fluvial incision (the lowstand shoreline that remained on the shelf, the low gradient of the shelf, the subsidence that affected the study area since MIS 5), the valleys appear to be deeply incised on the shelf, with valley flanks that can exceed 40 m in height. The model to explain the formation of the valleys comprises enhanced river discharge as the key factor in increasing river energy and promoting erosion across the low gradient shelf. Copyright © 2014 John Wiley & Sons, Ltd.

Relative Sea-Level Rise Scenario for 2100 along the Coast of South Eastern Sicily (Italy) by InSAR Data, Satellite Images and High-Resolution Topography

“…Concerning the role of the dune system in counteracting the SLR, field evidence and optical satellite images show that over the last two decades, the beach-dune systems have been subjected to a continuous retreat in consequence of multiple factors (Table 3), mainly, the sea-level rise, the increasing intensity of extreme marine events, VLM and deficit on the sediment supply in a coastal system. The high rates of land subsidence highlighted by InSAR, suggest that future scenarios could be driven by overtopping processes, rollover or dune breaching [112,113], probably similar in timing and architecture of resulting deposits, to retrogradation processes occurred during the marine transgression after the last glacial maximum (LGM) in different low-gradient settings [114][115][116]. In particular, the time series of satellite images of the sandy coasts at Siracusa between 2009 and 2020 (Figure 8, Table 3), show the occurrence of dune breaching near the salt-marshes over the last decades.…”

A late Quaternary multiple paleovalley system from the Adriatic coastal plain (Biferno River, Southern Italy)

“…Post-LGM incised-valley systems have been described uniquely from the Alpine sector (Tagliamento, Piave and Brenta incised valleys; Fontana et al, 2008Fontana et al, , 2013. Recently, a huge erosional feature (Manfredonia incised-valley system) was recognized in the Adriatic offshore, below the Apulian shelf, 70 km south of the study area (De Santis and Caldara, 2014;Maselli and Trincardi, 2013;Maselli et al, 2014).…”

The 5.5–4.5 kyr climatic transition as recorded by the sedimentation pattern of coastal deposits of the Apulia region, southern Italy

“…The Incoronata subsynthem is topped by a regional unconformity datable to the MIS 2 (Würm glacial) on which the NAQ unit lies. The latter consists of greyish terrigenous sand rich in marine fauna and is Holocene in age, particularly the post-MIS 2 transgressive phase (De Santis and Caldara, 2014; De Santis et al, 2010, 2013).…”

“…Locally, the marine sands are overlain by grey backshore and coastal dune sand. This unit is attributed to the Holocene epoch, in particular to the current highstand (De Santis and Caldara, 2014; De Santis et al, 2010, 2013).…”