Pedostratigraphical and geochronological characterization of late Pleistocene to Holocene depositional sequences from the Po Plain: loess and paleosols as paleoseismological markers.

Abstract

Loess represents one of the main paleoenvironmental archives recording Quaternary environmental changes. This study demonstrates that in Italy, at the Po Plain Loess Basin (PPLB), the most developed loessial sequences are preserved in association with morphotectonic structures, i.e. isolated hills, uplifted terraces and topographic highlands formed due to tectonically-induced drainage diversion. These landforms represent the surface expression of the complex interplay between the Pleistocene climatic changes and the compressional active tectonics which characterize the Po Plain foredeep. Such morphotectonic features, emerging a few meters above the surrounding fluvial plain because their moderate tectonic uplift rates higher than regional denudation/sedimentation rates, acted as sedimentary traps for aeolian sediments and preserved them. Therefore, the preservation of loess-paleosols sequences in correspondence of morphotectonic landforms makes loess a suitable tool to investigate not only the Quaternary climate changes, but also the recent tectonic activity and paleoseismology of the Po Plain. Four key loess-paleosols sequences preserved in setting controlled by active compressional tectonics (Solero, Rivarone, Pecetto di Valenza, AL; Monte Netto, BS) are presented, analysed through an innovative paleoseismological approach, integrating pedostratigraphy/micropedology and OSL/TT-OSL dating to structural analysis that allow to reconstruct the environmental conditions and tectonic activity of the Po Plain