New structural and stratigraphic data for a selected area of the Ligurian Alps are combined in order to assess
and discuss the role played by extensional structures in the southernmost segment of the Western Alps
during thrusting. Restored cross-sections and field data suggest that the structural style in the external sector
of the chain may depend upon the presence of pre-orogenic normal faults ascribed to three extensional
events linked to different geodynamic contexts: (i) Permian post-Variscan plate reorganisation, (ii) Mesozoic
rifting–drifting phases leading to the opening of the Alpine Tethys, and (iii) Eocenic development of the
European foreland basins. During positive inversion in Eocene times, a thin-skinned thrust system developed
in this area, followed by a thick-skinned phase. In both situations the inherited extensional structures played
fundamental roles: during the thin-skinned phase they conditioned the thrusting sequence, also producing
large-scale buckle folds and partial reactivations; during the thick-skinned phase the strain was
compartmentalized and partitioned by pre-existing faults.
The kinematic model of the external sectors of the Ligurian chain also allows the re-assessment of the Alpine
evolution of the front-foreland transition, including: (i) indirect confirmation that in the Eocene the Ligurian
Briançonnais and Dauphinois domains were not separated by the Valais-Pyrenean oceanic basin; (ii) that the
thin-skinned phase progressively changed into thick-skinned; (iii) the assertion that there were no
significant deformations from the Oligocene to the present-day, and the Corsica–Sardinia block rotation only
produced a change in orientation of previously formed structures and normal fault system development.
