Oligocene to Early Miocene sedimentation and tectonics in the southern part of the Calabrian‐Peloritan Arc (Aspromonte, southern Italy): a record of mixed‐mode piggy‐back basin evolution

Abstract

AbstractThe Calabrian‐Peloritan Arc (southern Italy) represents a fragment of the European margin, thrusted onto the Apennines and Maghrebides during the Europe‐Apulia collision in the late Early Miocene. A reconstruction of the pre‐Middle Miocene tectono‐sedimentary evolution of the southern part of the Calabrian‐Peloritan Arc (CPA) is presented, based on a detailed analysis of the Stilo‐Capo ďOrlando Formation (SCO Fm). Deposition of the SCO Fm occurred in a series of mixed‐mode piggy‐back basins. Basin evolution was controlled by two intersecting fault systems. A NW‐SE oriented system delimited a series of sub‐basins and fixed the position of feeder channels and submarine canyons, whereas a NE‐SW oriented system controlled the axial dispersal of coarse‐grained sediments within each of the sub‐basins. From base to top, sedimentary environments change from terrestrial and lagoonal to upper bathyal over a timespan of approximately 12 Myr (late Early Oligocene‐late Early Miocene). During this interval, extensional tectonic activity alternated with oblique backthrusting events, related to dextral transpression along the NW‐SE oriented faults. This produced a characteristic pulsating pattern of basin evolution.Oligocene‐Early Miocene evolution of the W. Mediterranean basin was dominated by ‘roll back’ of the Neotethyan oceanic lithosphere. Considerable extension in the overriding European Plate gave rise to the formation of a back arc‐thrust system. The initial stages of Calabrian Basin evolution are remarkably similar to the evolution of rift basins in the back arc (Sardinia). The Calabrian basins, which are inferred to have originated as thin‐skinned pull‐apart basins, were subsequently incorporated into the Apennines‐Maghrebides accretionary wedge by out‐of‐sequence thrusting, and became decoupled from the back arc. Periodic restabilization of the accretionary wedge, resulting in an alternation of backthrusting and listric normal faulting, provides an explanation for the structural evolution of these mixed‐mode basins. The basins of the southern part of the CPA may be termed ‘spanner’ or ‘looper’ basins, in view of their characteristic pulsating structural evolution, superimposed upon their migration toward the foreland. This new term adequately accounts for the occurrence of tectonic inversions in long‐lived piggy‐back basins, as expected in the light of the dynamics of accretionary wedges.