Fold‐and‐Thrust Belt and Early Alpine Relief Recorded by Calcite U–Pb Dating of an Uplifted Paleo‐Canyon (Vercors Massif, France)

Abstract

The long‐term evolution of orogenic drainage systems is closely related to the propagation of tectonic structures, which gives rise to the topography and hence anisotropies for river incision. This study focuses on the subalpine Vercors Massif (SW French Alps), reconstructing the geometry of an uplifted paleo‐canyon and applying calcite U–Pb dating to its carbonate‐rocky talus slope deposits. U–Pb ages of the blocky calcite veins range from 58 to 9 Ma, related to multiple tectonic motions along the E‐W compressive fault on which the paleo‐canyon was dug. U–Pb dating on calcite cement sealing the breccia porosity yields a minimum age of ca. 2 Ma for the paleo‐canyon abandonment and rockfall infill. Cementation of the breccia, infilling and uplift since the late Neogene to Pliocene times highlight the reorganisation from radial to longitudinal drainage in relation to frontal Alpine tectonics and surface uplift of the western French Alps.