Successioni alluvionali terrazzate nel medio bacino del Metauro (Appennino Marchigiano) – Datazione con il 14C

Terraced alluvial successions in the middle Metauro River basin (Marche Apennines) ¹⁴C Dating

Abstract

A wood fragment attributable to Pinus type sylvestris, deriving from the Metauro-Candigliano rivers confluence (Northern Marche) dates back, by the means of ¹⁴C, to more than 41000 years B.P.. The dated sample has been found into a sandy-silty alluvium locally constituting the lowermost unit of the third-order terraced fluvial deposits. This lithostratigraphic unit, although almost completely eroded before the deposition of the pebbly-sandy sequences characterizing the third-order alluvial terraces, seems to be present in many North-marchean rivers. On the basis of the radiometric dating and of the lithostratigraphic and geomorphologic data it is possible to refer this deposit to the early Würm or to the late Riss- Würm . It is interpretable as a low-energy river deposit and is probably related to valley bottoms covered with vegetation, partially represented by Pinus type sylvestris. The almost complete erosion of the dated lowermost unit has been followed by the deposition of a pebbly-sandy succession constituted by braided-river sequences (Fb) overlain by alluvial-fan ones (Ca). The whole succession has been reincided and terraced during the late Würm -Holocene.