Protracted Subduction of the European Hyperextended Margin Revealed by Rutile U?Pb Geochronology Across the Dora?Maira Massif (Western Alps)

The Dora-Maira massif is an archetypal nappe stack of subducted and exhumed upper crust. Slices continental crust experienced metamorphism at blueschist to ultrahigh-pressure (UHP) eclogite-facies conditions. While the timing peak in UHP unit has been extensively studied, little known about other units. In order constrain conditions high-pressure metamorphism, U-Pb-trace element analyses rutile titanite were carried out across stack. data reveal Alpine metamorphic ages younging downwards stack, from ?40 ?33 Ma. Greenschist-facies retrogression whole occurred ?32–31 Ma, after lowermost (Sanfront-Pinerolo Unit). Tectonic implications include (a) continuous fast exhumation crust, (b) long-lived subduction ?60 Ma distal European margin, reconstructed be a hyperextended margin spread over ?130 km for alone, (c) initiation collision synchronous with end metamorphism.