Deep gravitational processes in the Maratea valley (southern Italy): evidence from high resolution reflection seismic profiling of the surrounding offshore

Abstract

The Maratea Valley (Basilicata) is characterized by deep gravitational movements involving the Meso-Cenozoic calcareous-dolomitic formations (tectonic units «Alburno-Cervati» and «Bulgheria-Verbicaro») interpreted as sackung-type phenomena. The complex morpho-structural setting of the area has been influenced by the Pleistocene extensional tectonics, probably still active. Tectonic dislocations, characterized by a strike-slip component on a regional scale, have caused the superimposition of the Bulgheria-Verbicaro Unit on the Crete Nere Formation and the tectonic contact of the last formation on the Alburno-Cervati unit, cropping out on the right flank of the valley. This paper reports on evidence of the seaward prolongation of the Maratea Valley, based on the geological interpretation of high resolution seismic reflection profiles, recently acquired in the surrounding offshore area. The morpho-bathymetry of the area shows steep and articulated sea bottoms, resulting from the seaward prolongation of the rocky coastal cliffs, up to a water depth of –30 m, where the continental shelf starts. The sea bottom then becomes more regular, up to the shelf break, located at about 2 km of distance from the shoreline, at water depths ranging from –100 m and –120 m. The shelf break is articulated and incised by deep channels linked to the head of a submarine canyon (the Maratea canyon). The canyon is affected by a regressive erosion that is probably still active and controlling the submarine gravity instabilities identified in the slope sequences recognised in the seismic reflection profiles.