Plio-Quaternary continental deposits of Castellamonte area, between Orco and Dora Baltea Basins (Torino Province, Italy)

A new geologic mapping of the area near Castellamonte (Torino Province) describes the wide Plio-Quaternary continental succession, up to about 100 m thick. This sequence is distinguished according to allostratigraphyc criterium; the altimetrical position, the degree of pedogenesis and the supply by different basins are also used. Within a single unit several lithofacies are distinguished. Fine-coarse grained fan-delta sediments (Vespia Alloformation) are described in the lower part of the continental succession: the diffusion of fossil plant remains indicates an Early-Middle Pliocene age. These sediments show an evident deformation and fill ancient lacustrine basins, likely according to the Canavese Line trend. Their wide distribution and considerable thickness suggest former conditions of subsidence. Coarse-grained glacial, outwash and fluvial sediments (Colleretto Castellonuovo, S. Defendente, Case Musso, Pagliero, Serra and Piverone Alloformations) are described in the upper part of the continental succession. They consist of undeformed sediments deposited during Middle to Late Pleistocene. These sediments indicate the presence of small local glaciers according to the current valleys trends. The terracing ratios among the different alloformations and their small thickness indicated a subsequent differential uplift.