Thermochronological Evolution of the Northern Apennines

In this work we show the results obtained with the apatite fission-track and (U-Th)/He methods applied on the Oligo-Miocene foredeep successions of the Northern Apennines. Results show that samples coming from west of the present drainage have been clearly totally reset for both thermochronological systems. Time of cooling below ca. 100°C is between about 10 and 3 Ma, with a slight decrease eastward. This decrease is more marked for cooling below 70°C, which vary from about 9 Ma to as young as 1 Ma. East of the drainage divide, fission-track and He systems are either partially reset or unreset. Here the amount of cover removed above the analyzed apatites was not sufficient to completely anneal fission tracks or to cause a total loss of He. Burial depths estimated from the data allow reconstructing the shape of the Ligurian Unit as a lid overriding the foredeep rocks until nearly the Adriatic Sea.