Magnetic fabric and structural setting of Plio-Pleistocene clayey units in an extensional regime: the Tyrrhenian margin of central Italy

Abstract

Results are presented of structural analysis and anisotropy of magnetic susceptibility (AMS) analysis of Plio-Pleistocene clayey units from the extensional Tyrrhenian margin of central Italy. Data have been collected in different tectonic settings, mainly strike-slip and transverse extensional structures. At the sites with major evidence of Plio-Pleistocene tectonics, there appears a close relationship between magnetic lineations and stretching directions. Stretching processes that were able to modify the original magnetic fabric pre-dated significant normal-fault-related tilting, and therefore were active at the very first stage of extensional deformation. The relationships between AMS and structural trends in an extensional regime seem distinctively different from those reported in compressional regimes. This kind of analysis may be useful in the geodynamic interpretation of ambiguous structures.