The Crati River Basin: geomorphological and stratigraphical data for the Plio–Quaternary evolution of northern Calabria, South Apennines, Italy

In this paper, we present the results of an integrated geomorphological and stratigraphical study carried out in the eastern side of the Crati River valley (northern Calabria, South Italy). This area is characterized by the occurrence of three order palaeosurfaces that, along with low-sloping palaeovalleys and structural landforms, are striking features of the landscape. The relationships between morpho-tectonic and sedimentary evolution of the Crati Basin has been assessed through sandstone detrital modes, morphostratigraphy and geomorphological correlation with adjacent areas. The two main unconformity surfaces that typify the Quaternary fill were correlated to different steps of landscape evolution. The presence of both erosional and depositional palaeosurfaces has been a useful marker for reconstructing sedimentary and morphogenetic events, and hence to detect drainage network evolution and changes in source sediment area. In particular, we recognized that the study area experienced, during the late Pliocene–Early Pleistocene a period of sub-aerial landscape modelling as suggested by low-sloping palaeovalleys and related fluvial deposits (1st Order Palaeosurface). At that time, the source of the detrital constituents of the PPS Unit sandstones was mainly from the Sila Massif. The onset of Coastal Range identification and uplift (Early Pleistocene) marks a change in the geomorphic scenario with tectonic driven stream incision and valley development along the eastern side of Coastal Range, along with the occurrence of depositional and erosional landsurfaces (2nd Order Palaeosurface) at footslopes. During this period, the Coastal Range and Sila Massif were the sources for the detrital constituents of the PlS Unit sandstones. The progressive uplift of Coastal Range during late Early Pleistocene and the marked backstepping of the depositional systems along the Sila footslope was accompanied by alternating phases of down-cutting and base-level stability resulting in the development of a step-like distributed 3rd Order Palaeosurface. The presence of dolostone in detrital modes is clear evidence of stream piracy phenomena of ancient palaeovalleys by the Crati valley-facing drainage network