I travertini di Canino (Viterbo, Italia Centrale): Elementi di cronolitostratigrafia, di geochimica isotopica e loro significato ambientale e climatico

Abstract

The Canino Travertine Formation outcrops in an area situated between the western slopes of the Mount Doganella-Mount Canino ridge and the Fiora river, extending about 14 genetically connected with the hydrogeological system of the above-mentioned ridge, where thermal encrusting springs characterized by the mixing of Ca-Mg bicarbonate-sulfate and Na-CI waters are at present still active. The Formation morphologic features are described; several superimposed travertine bodies, at times separated by either not-depositional or erosional phases, have been recognized. In the upper part of the Formation there are two anthropic horizons, dated about 5 ka B.P. and VI Century b.C. respectively on the basis of radiometric dating and archeological finding. Compositional, floristic and faunal characteristics of the horizons are described. The deposition of travertine has been active since Middle Pleistocene times at least and is still in progress. The oxygen and carbon isotopie composition of travertine has been studied in a sequence formed between 57 ka and 2÷3 ka B.P. The isotopie curves, the dating of several travertine samples and the geological data collected have allowed for the reconstruction of the palaeoenvironmental and palaeoclimatic evolution of the studied sequence from Stage 3 through the Last Glacial to the Holocene and the approximate evaluation of the biogenetic productivity. The climatic signal showed by the isotopie oxygen curve matches fairly well the isotopie curves given by several authors, concerning ocean and/or continental deposits of the same age.