Kinematic characterization and deformational evolution of quaternary faults displaying a Holocenic activity: Some cases in the Central Apennines (Italy)

Geological and structural researches on Quaternary faults in key-areas of Umbria-Marche and Abruzzi in the Central Apennines, emphasised the occurrence of complex kinematic conditions, which are characterised by various and alternating generations of slip vectors along the same fault plane. Quantitative analyses of these structures allowed the reconstruction of a mean ellipsoid of finite extensional deformation characterised by a NE-SW stretching direction and a vertical shortening axis. The Quaternary tectonic framework is characterised by kine-matically interconnected active thrusting - in the Adriatic off-shore - and normal faulting - in the Apennines ridge -, which gave rise to a progressive deformation with mean shortening and extensional axes both trending NE-SW. Oblique ramps and transfer faults commonly developed along pre-existing N-S and E-W trending structures (such as Jurassic and Cretaceous faults). This complex kinematic situation is interpreted in terms of mechanical interactions caused by the variation of one or more tectonic stress modules, associated with the presence of oblique ramps and transfer faults.