The orogenic effects on forebulge evolution: A case study from Cenozoic deposits in the Salento Peninsula, Italy

Abstract

The Salento Peninsula is a part of the larger Apulia Carbonate Platform, one of the carbonate platforms that have developed along the southern margin of the Tethys Ocean since the Triassic, above the Adria microplate. This peninsula represents the culmination of a lithospheric anticline formed due to the subduction of the Adria Plate beneath two mountain belts migrating in opposite directions: the Dinarides-Albanides-Hellenides (DAH) chain, moving from NE to SW, and the southern Apennines (SA) chain, moving from SW to NE. Consequently, the Salento Peninsula represents the foreland sector of these two mountain belts, whose different migration rates, deeply influenced the carbonate sedimentation and paleogeographic evolution of this area over the last 60 Myr. In our study field analysis, a database of 350 wells, and 90 seismic lines calibrated with 3 exploration wells were employed to characterize the physical stratigraphy and depositional setting of the Salento Peninsula and define its paleogeographic evolution during the Paleogene and Neogene. Our results suggest that temporal variations in sedimentation rates and types as well as the reduced thickness (maximum 200 m) of the Cenozoic stratigraphic succession in the internal sectors and both along the Adriatic and Ionian margins of the Salento Peninsula are directly or indirectly linked to the migration rates of the DAH and SA chains. These migration rates played a role in determining changes in subsidence rates, the occurrence of soft-sediment deformation, and the influx of Plio-Pleistocene fine-grained terrigenous sediments, especially along the Ionian margin. Although the investigated succession exhibits a reduced thickness, it comprises several lithostratigraphic units bounded by unconformity surfaces. Within these units, a stack of complete and incomplete simple and composite high- and low-rank depositional sequences has been recognized. Our data suggest that these units are the result of a multifold cyclicity, reflecting the close interaction between eustatic sea-level changes and the tectonic setting of the area.