Quantifying deformation processes in the SE Pyrenees using U–Pb dating of fracture-filling calcites

A significant challenge in brittle fold and thrust belts analysis is to quantify the timing of the deformation processes, since suitable minerals for dating and well-preserved growth strata sediments are scarce or absent. Here, we quantify the duration of thrust sheet emplacement and shortening rates in the SE Pyrenean thrust sequence using U–Pb dating of fracture-filling calcites. The obtained U–Pb dates reveal a minimum duration for the emplacement of each thrust unit (18.7 Ma for the Bóixols–Upper Pedraforca, 11.6 Ma for the Lower Pedraforca and 14.3 Ma for the Cadí­), and that piggy-back thrusting was accompanied by post-emplacement deformation of upper thrust sheets above lower ones during their south-directed tectonic transport. Shortening rates of 0.6 mm yr^-1, 3.1 mm yr^-1 and 1.1 mm yr^-1 from older to younger emplaced thrust sheets were calculated. The results also reveal the formation of local normal faults during the late Oligocene as a result of the late stages of compression and exhumation in the SE Pyrenees. Finally, we observed that temperatures higher than 110 °C could be a limiting factor when applying the U–Pb dating method.