Late Pleistocene Post-Glacial Sea Level Rise and Differential Preservation of Transgressive “Sand Ridge” Deposits in the Adriatic Sea

Abstract

Linear sand bodies with ridged or mounded morphology are commonly referred to as "sand ridges". Their origin may reflect a great variety of depositional processes and environments, although many examples from modern shelves include near-shore transgressive deposits formed during the last post-glacial sea level rise. These transgressive sand ridges, however, are not present on all the margins drowned during this interval, indicating that local environmental factors contribute to their formation and preservation. Transgressive sand ridges are recognized on the South Adriatic shelf in water depths between 90 and 120 m, where they overlay a major unconformity originated during the last glacial sea level fall and lowstand. In contrast, they are absent on the Central Adriatic shelf, where transgressive deposits above the glacial unconformity fill erosional scours without forming relief on the seafloor. The transgressive sand ridges on the South Adriatic shelf appear roughly elongated parallel to the bathymetric contour and are locally as thick as 15-20 m. Core data indicate an overall coarse-grained composition, with a relevant bioclastic component. Their limited distribution reflects the importance of local variation in shelf morphology and sediment sourcing at the onset of sea level rise. In particular, their deposition and preservation are favored in less subsiding shelf sectors characterized by higher gradients and tectonic relief, where transgressive erosion and reworking of pre-existing lowstand deposits is also more efficient.

The Depositional Environments in the Cilento Offshore (Southern Tyrrhenian Sea, Italy) Based on Marine Geological Data

“…Following a general climate warming [66][67][68][69], during the Upper Pleistocene Holocene, there was a rapid rise of sea level on a global scale [70][71][72][73][74]. Transgressive and highstand deposits have been individuated on the continental shelves all around the world [26,[75][76][77][78][79][80]. During the transgression, the high rate of the sea level rise and the low gradient of the Cilento continental shelf led to the almost simultaneous submersion of large areas and to the drastic landwards shift of the coastal facies.…”

The uplift of the Adriatic flank of the Apennines since the Middle Pleistocene: New insights from the Tronto River basin and the Acquasanta Terme Travertine (central Italy)

“…At least four main levels of alluvial terraces, Late Pleistocene to Holocene in age, are present along the valley margins of the Tronto River (Coltorti and Farabollini, 2008). Bore-hole and seismic profiles in the Adriatic Sea indicate that, since the Quaternary, the coastline standed in a position similar to the present one, except for the glacial periods when it moved several kilometers to the east (Cattaneo et al, 2003;Ridente et al, 2008;Catanzariti et al, 2009;Pellegrini et al, 2015;Ridente, 2018).…”

Assessing Fine-Scale Distribution and Volume of Mediterranean Algal Reefs through Terrain Analysis of Multibeam Bathymetric Data. A Case Study in the Southern Adriatic Continental Shelf

“…Interestingly, in our surveyed area, C build-ups are in contact with an erosional truncation that marks the top of the underneath sequence ( Figure 6). The erosional truncation can be associated to aerial erosion of past highstand marine deposits, or to the ravinement surface formed at the onset of the post-glacial sea-level rise, that on the South Adriatic shelf margin enhanced transgressive erosion of older deposits [42]. Both the reflectors (the seafloor and the erosional truncation) were digitalized and exported to calculate the thickness of C frameworks for all survey lines ( Figure 6).…”