Stratigraphy and evolution of a long-lived fluvial system in the southeastern Alps (NE Italy): the Tagliamento conglomerate.

The Tagliamento River, located in the eastern Southern Alps, represents a unique opportunity to study the evolution of this sector of the chain over the last 6 Ma because of its relatively well preserved deposits. The development of the fluvial system has been reconstructed for the period since the Messinian, when the valley was deeply carved and uphead eroded, and the drainage basin was widened. The deposits preserved along or close to the present valley have been subdivided into five allostratigraphic units on the basis of bounding unconformities, supported also by petrographic (pebble and sandstone) data, facies and structural analysis. The units are characterized by different composition and sources, permitting a reconstruction of the changes in the drainage areas. The angular unconformities that bound the units as well as the deformations affecting the deposits indicate that the eastern Southalpine Chain has been tectonically since the Messinian.