U/Th dating of freshwater travertine from middle Velino Valley (Central Italy): paleoclimatic and geological implication

Six travertine bodies outcropping along the Middle Velino Valley (Central Italy) have been studied and dated using the U/Th method in order to obtain new chronological constraints for the recent geological evolution of the area. The lithological and sedimentological characteristics of travertines have been described,showing that such deposits can be referred to waterfall,pool terraces and gentle slopes environment. Travertines have formed during warm periods and can be referred to marine oxygen isotope stages 5,3 and 1. Travertine deposition seems to stop around 5 ka BP according to other European and Italian sites. Pollen stratigraphy and ostracod assemblages from the close sequence of Valle di Castiglione,characterized by the same climatic conditions of Velino Valley, have confirmed that periods of Velino Valley travertine deposition were effectively characterized by warm and wet climatic conditions. Seismic activity strongly active in the area since the Middle Pleistocene has deeply influenced the location and the discharge of springs which have deposited the travertines,influencing in turn the shape and size of travertine bodies. 6 2002 Elsevier Science B.V. All rights reserved