I travertini delle Alpi Cozie settentrionali: significato geologico, paleoecologico e paleoambientale

In the northern Cottian Alps we find numerous outcrops of travertine localised along slopes modelled by successions of meta sedimentary rocks with a prevalence of calc schists. Analysis of the sedimentological characteristics and tissues has led to the definition of 4 types of carbonate: hillside breach, phytothermal travertines, stromatolitic travertines and the classic travertines. Moreover, the morphological characteristics of the source areas and the sedimentary bodies, and the association of different travertines have allowed us to distinguish three deposit environments: hillside travertines, collapse and river dam. The distribution of travertine shows clearly the strong link between the processes of carbonate precipitation in subatmospheric environments and the presence of conditions of fracturing and disintegration of rocky substrata linked to the presence of phenomena of gravity collapse concerning the Alpine relief. The information obtained by isotopic dating of the travertines in the Susa and Chisone valleys demonstrate that these deposits had accumulated during a period of between 11500 and 9500 years, succeeding the definitive retreat of the glaciers at the end of the last ice age. Moreover, the paleobotanic remains that have been conserved inside these carbonates, and following other considerations of a paleoenvironmental nature, have allowed us to attribute to certain sections of the Susa Valley the role of a zone of refuge for populations of mountain pine (Pinus mugo) during the last alpine ice age