LA DISTENSIONE TOSCO-TIRRENICA COME POSSIBILE MOTORE DELLA COMPRESSIONE APPENNINICA

Abstract

Tue Tyrrhenian-Apennine region consists of a "rift/fold­and-thrust belt" couple that has been developing since the middle-late Miocene. Rifting propagated eastward towards the Adriatic foreland to produce a series of offshore and on­shore asymmetric graben and normai fault systems. Similar­ly, a compressive front some tens of chilometers eastward of the rift zone allowed the progressive emplacement of thrust sheets and the development of foredeep basins. We infer that the extensional deformation of the Tyrrhenian rift zone oc­curs by the discontinuous shear across a sequence of faults that basically detact at the base of the crust while lithospher­ic mantle thinning occurs by prevalent ductile deformation. Involvement of the entire crust in the extensional process, at least in the southern Tyrrhenian Sea is evidenced by the unroofing of mantle harzburgites sampled during the ODP Leg 107 drilling of the Vavilov basin (site 651). [...]