Structural and hydrogeological features of Pleistocene shear zones in the area of Rome (Central Italy)

The last tectonic episode observed in the Latium Tyrrhenian margin (Central Italy), few km cast of Rome, is represented by a set of middIe-upper Pleistocene N-S shear zones, characterised by complex geometric and kinematic setting. The easternmost of these shear zones displays a strike-slip component of motion and is located at the boundary between the Apennine carbonate chain and the volcanic areas. The distribution of travertine deposits and hydrothermal springs suggests that this fault zone acts as an impermeable barrier for lateral flow derived from superficial karstic circuit, and as a preferential upwelling surface for deep hydrothermal fluids. We propose that high fluid pressure could develop inside these fault zones favouring the reactivation of buried pre-existing crustal discontinuities and the local re-orientation of the stress field, as testified by the geometry and the kinematics of the surface fault pattern.