Reconstruction of continental margin architecture deformed by the contraction of the Lagonegro Basin, southern Apennines, Italy

Thrust propagation through previously lifted continental margins may result in fold and thrust belts whose structure is strongly controlled by the inh erited basin architecture, as it occurs in southern Italy. The Lagonegro un its of the southern Apennines comprise a deformed pelagic basin succession showing variable stratigraphic characteristics, mainly lateral variations i n both facies and thickness, interpreted to be due to a complex basin topog raphy related to a Triassic rifting event. In contrast to previous studies, cross-section balancing and restoration indicate that the Lagonegro units exposed in the high Agri Valley area suffered relatively limited internal s hortening (8 km, i.e. 35%). Early deformation of these rocks, later incorpo rated into a large-displacement thrust sheet, was dominated by folding arou nd (present-day) roughly north-south-trending axes. The attainment of a reg ional decollement level was favoured by an early mild inversion of the basi n, producing a roughly similar structural elevation of both hanging-wall an d footwall successions to Mesozoic faults. Most of the contractional deform ation was accommodated by buckling of the Mesozoic syn-rift strata between synsedimentary faults, which represented major mechanical interfaces. Early strain localization in the Lagonegro Basin ahead of the active thrust fron t was most probably mechanically controlled by a faulted crustal segment wh ich originally lay, within the continental margin, between two massive carb onate platforms.