Zircon fission-track analysis on modern sands shed from the Alps: notes on separation procedures and state of the art

Detrital zircon fission-track analysis on modern sands is a valuable approach to constrain the pattern of erosional exhumation in orogenic source areas (e.g. Bernet et al., 2004). In order to constrain the short-term and long-term erosion pattern in the Alps-Apennines orogenic couple, we have collected samples of modern sands in selected sites of the Po River Delta, as well as along the Po River main trunk and in most of its tributaries. Zircon concentrates were separated according to a specific quantitative procedure coupled with sedimentological analyses, which allows an evaluation of zircon content in source rocks, of hydraulic sorting effects, and related intersample/intrasample zircon variability (Garzanti et al. 2008, 2009). Such analyses are the key point to perform sediment budgets and erosion-rate calculations starting from the identification of specific age population within grain-age distributions, and to constrain the short-term evolution of the belt thanks to the information stored in modern sediments.