Abstract

Apatite fission-track analysis has been applied on 24 samples from the geometrically upper units (Internal and External Ligurids) of the Northern Apennines nappe pile. They yield ages between c. 20 Ma and c. 6 Ma. Two samples were also dated with fission tracks in zircon (ages of c. 155 Ma and c. 199 Ma). Together the data reveal that during post-Late Cretaceous compression the Internal Ligurids reached temperatures to completely anneal fission tracks in apatite (T>c. 120 °C) but not in zircon (T<c. 300°C). After Eoccne continental collision these rocks were cooled (below c. 120°C) and started again to retain fission tracks in apatite. Since the Oligocene a further burial under episutural sediments ensued that caused a partial to total apatite fission-track annealing. During a final phase of cxhumation the sedimentary cover was removed. This exhumation can be linked to Late Miocenc extensional tectonics, that started at c. 8–9 Ma in the central and southern portions of the study area.

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