Plio–Pleistocene Sedimentation in the Apenninic–Adriatic Foredeep (Central Adriatic Sea, Italy)

Summary

The Plio–Pleistocene foredeep in the Central Adriatic Sea exhibits a number of syndepositional tectonic structures. The structures are elongated NW–SE, and match the depositional axis of the Adriatic basin. Three depositional seismic units have been recognized: Unit 1, Pliocene in age, is divided into Sub-units a and b, Unit 2 of Pleistocene age, and Unit 3 (Pleistocene) lateral to Unit 2. Unit 1 consists of an onlap turbiditic and hemi-pelagic sequence mainly deposited parallel to the tectonic strike. Unit 2 is a deltaic and slope system that prograded from the Apennines. Unit 3 is deltaic too but prograded parallel to the basin axis and perpendicular to the trend of Unit 2. Structural highs, produced by thrusting, were subsequently eroded and detritus was shed (as channel deposits or slumps) into the basin forming denudation complexes. The faulting in the external area consists of blind faults and associated fold drapes that had a negligible influence on sedimentation. The foredeep migration was coupled with the deformation movements in the basin itself, and these, in turn, matched with the lateral and vertical building of Unit 1. From the structural point of view the following arise: (a) the foredeep is segmented by structural discontinuities (tear faults, lateral ramps, etc.), (b) the foredeep is strongly affected by thrust deformation, (c) the foredeep is detached from the basement by the most external fault.