Piggyback basin development and thrust belt evolution: structural and palaeostress analyses of Plio-Quaternary basins in the Southern Apennines

Abstract In southern Italy, structural analysis of the intramontane Pliocene-Quaternary terrigenous basins of Sant' Arcangelo and Ofanto shows that they are piggyback basins. The recent uplift of the Southern Apennines provides good conditions for carrying out detailed studies of palaeostresses in relation to structure and sediment accumulation in such piggyback basins. We demonstrate that in the Pleistocene Sant' Arcangelo marine basin, a single N70° compression induced a complex pattern of folds and strike-slip faults. In contrast, the older Pliocene Ofanto basin reveals a polyphase history characterized by successive tilts and palaeostresses according to different compressions. In both basins, compressional stresses are syn-depositional. The geometry of the sedimentary infill of these basins provides information on the thrusting activity in terms of location, geometry and age. We point out that, in addition to sedimentary and structural studies (including interpretation of seismic reflection data), palaeostress analyses provide a valuable tool for deciphering development and evolution of compressional basins in a fold-and-thrust belt.