Magnetic fabric of Pleistocene clays from the Tyrrhenian arc; A magnetic lineation induced in the final stage of the middle Pleistocene compressive event

Abstract

We present the results of an analysis of the anisotropy of magnetic susceptibility (AMS) in early Pleistocene clay sediments from the southern Apennines and its foreland (Apulia). Measurements were performed on samples from different tectonic units; the Apulian Unit, the Bradano Unit, and the Apenninic belt. The AMS is characterized by a dominant magnetic foliation parallel to the bedding plane in all cases, pointing to a primary sedimentary magnetic fabric. No lineation is found in the clays from the Apulian Unit, whereas the inner part of the Bradano Unit and the Apenninic belt show a clear NW–SE trending magnetic lineation which is perpendicular to the main compressive stresses known for this area. There is a very consistent WNW‐ESE trending magnetic lineation for the clays from the southern Apennines and the Calabrian block to the south. Correction of this lineation with the established tectonic rotations shows that the lineation is clearly of postrotational origin and reflects the latest stages of deformation. The lineation is linked to middle and late Pleistocene tectonics: its alignment occurred in the final stages of the compressive event affecting the Tyrrhenian arc system. For the Sant'Arcangelo basin in the southern Apennines, anomalous trends of magnetic lineation (compressive stress) were established.