Late orogenic transpressional tectonics in the «Ligurian Knot»

L. Crispini(**), L. Federico(*), G. Capponi(*) & C. Spagnolo(*)
(*) Corresponding author: Laura Crispini - Dip.Te.Ris., Corso Europa, 26 - 16132 Genova, Italy, Phone: +390103538204; Fax: +39010352169; Email: crispini@dipteris.unige.it. (**) Dip.Te.Ris. (Dipartimento per lo Studio del Territorio e delle sue Risorse). Università di Genova, Corso Europa, 26 - 16132 Genova, Italy.

This study focuses on the Tertiary tectonic evolution at the boundary between Western Alps and northern Apennines in central Liguria (Italy). The architecture of the two belts derives from the oblique convergence between the Europe and Adria plates and hence this area represents an ideal case to study the crustal structures that develop during oblique lithospheric convergence. The analysis of the Oligocene-Miocene brittle structures reveals: the occurrence of principal displacement zones with related minor structures that fit a transpressional dextral regime and a NE-SW direction of maximum shortening; a regional strain partitioning between wrench-dominated and contraction-dominated domains; a structural control on the orientation and development of brittle structures by the pre-existing weaker pathways, provided by the alpine foliations and ductile shear zones. The principal displacement zones can be easily framed in the Oligocene-Miocene geodynamics of the «Ligurian knot», where the right-hand strike-slip component of the system provided a release of the Ligurian Alps from their southeastern segment, thus allowing the tightening of the arc of the Western/Ligurian Alps.

Transpression, Late orogenic tectonics, Sestri-Voltaggio Fault, Ligurian Alps, Ligurian knot.