Late Pliocene - early Pleistocene compressional tectonics in offshore Campania (eastern Tyrrhenian sea)

The interpretation of available multichannel seismic profiles, and the subsidence analysis of boreholes, which shows notable short-term departures from the expected long-term trends for basin subsidence, allow to recognize a late-stage phase of compressional tectonics, Late Pliocene-Early Pleistocene in age, in offshore Campania, between the Sorrento Peninsula and Cape Palinuro. In connection with the Tyrrhenian Sea opening, extensional and strike-slip tectonics have developed in this area since Late Miocene, mostly after the major compressional phases that built up the western sectors of the Southern Appeninic fold and thrust belt. Seismic lines show that tectonic deformation occurred along a major system of SW-NE trending listric faults, also controlling the present-day half-graben setting of the Salerno Basin. The Late Pliocene - Early Pleistocene compressional phase (which shows a NNW-SSE direction for the maximum horizontal shortening) reactivated the pre-existing SW-NE fault system and was respon sible for tectonic inversion within the Salerno Basin. It also caused the development of sballowing-upward sequences on the top of the forming compressional structures, as well as deformation and flexural uplift to subaerial exposure of basin flanks (Mesozoic carbonate reliefs together with part of the Lower Pleistocene basin infill), and, ai the same time, subsidence in the basin center. According to our interpretation, compression may have a fundamental role in controlling or enhancing tectonic uplift and/or subsidence, and tectonic phases recognized ai sea can be tentatively correlated with "neotectonic" evidence documented on land. After Early Pleistocene, a new generalized tectonic subsidence started in the Salerno Basin, but, in later times, compression was still going on in some restricted areas within the Salerno Basin and close to the southern border of the Picentini Mountains, towards the inner part of the Sele Plain. Tectonic deformation and erosional truncations within the Upper Pleistocene sequences in the offshore south of Salerno, as well as local tectonic uplift of uppermost Pleistocene deposits several meters above the present-day sea level on land, suggest that compressional events may have still been active up to very recent times. Evidence of Late Neogene-Quaternary compressional tectonics in extensional domains, has already been described for several places in the Mediterranean and in the northern Atlantic region. We infer that this "non-orogenic" contractional phase, which seems to be of regional extent, may be related to major intra-plate stress changes.