Stratigraphy and tectonics offshore of Puglia (Italy, southern Adriatic Sea)

Abstract

The structural and stratigraphic framework of Puglia offshore between the Gargano promontory and the town of Brindisi (southern Adriatic Sea) has been analysed based on 1700 km of multichannel seismic profiles and 10 exploratory wells. The area includes two different geodynamic settings: (1) part of the undeformed Apenninic foreland (“Apulian carbonate Platform”), consisting mainly of shallow water Mesozoic carbonates, and (2) part of the southern Adriatic Basin, which represents the foredeep of the Hellenic thrust system. A Mesozoic slope, buried by Tertiary clastics and corresponding to the edge of the Apulian carbonate platform, is observed on seismic data. The present physiography of the escarpment is the result of an erosional retreat mainly developed during the Tertiary and related to the subsidence of the South Adriatic Basin; at the same time carbonate facies belts, as evidenced by well data, seem to suggest that in some sectors of the margin the original Mesozoic physiography has been preserved and fossilized. Three seismostratigraphic units, separated by regional or local unconformities, have been distinguished in the Neogene clastic sequence of the South Adriatic Basin. Significant deformations in the sedimentary cover are represented by various antiforms. One of these antiforms, named the “Gondola” ridge, is an elongated, positive structure deforming the pre-Tertiary basement. The western sector of the Gondola ridge belongs to a major E-W strike-slip lineament extending on land in the Gargano promontory. In the eastern part of the area in question some tectonic features, resembling “pop up”-like and thrust antiforms, are arranged along an arcuate pattern named here “Grifone” trend. The Grifone trend structures indicate a post-Pliocene tectonism probably related to the late stages of the Dinaric-Hellenic orogenesis. The recent westward migration of the Hellenic fold and thrust belt can be demonstrated by the South Adriatic foredeep shift during the last 5–6 million years.