U/TH Dating of Pre-Holocene calcareous tufa deposits in the Umbria-Marche Apennine (Italy)

Abstract

This note describes the characteristics of two calcareous tufa (freshwater travertine) deposits found in the Umbria-Marche Apennines. The first has grown in the Laverinello Valley, a tributary of the upper Potenza River, along with the road from the village of Poggio Sorifa; the second deposit originated in the Val di Sasso Valley, a tributary of the upper Esino River, on the edge of a waterfall, currently inactive and disconnected from the current drainage network. The U/Th dating of samples taken from the investigated tufa deposits (55 ± 6 ka BP - 58 ± 6 ka BP, 65 ± 8 ka BP - 67 ± 5 ka BP, respectively) place them in the Late Pleistocene, in correspondence with sharp warming peaks within freezing periods. These dates support the genetic model of freshwater travertine deposition proposed by Dramis & alii (1999), based on the control exerted by the formation in the aquifer of a reversed thermal gradient in correspondence with climate warming.