Timing of granite emplacement, crustal flow and gneiss dome formation in the Variscan segment of the Pyrenees

International audienceThe Variscan segment of the Pyrenees is well suited to study the timing of crustal-scaledeformations as crustal flow and gneiss dome formation. This has been constrained from a synthesisof available structural and geochronological data of intrusive rocks, as well as new zirconU–Pb age determinations via laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS). After a stage of moderate thickening by fold–thrust belt development in theupper crust between 323 and 308 Ma, the Variscan segment of the Pyrenees experienced crustalflow at c. 306 Ma and then gneiss dome formation at c. 304 Ma. Localization of the deformationalong reverse-dextral shear zones occurred at c. 300 Ma. The Variscan segment of the Pyreneesrecorded a high-temperature regime, which allowed crustal flow of the middle crust, but withlimited amounts of heat which induced rapid cooling. The development of this enigmatic orogenicsegment of the Variscan belt is closely contemporaneous with the formation of the Cantabrian Oroclineand could correspond to a lithospheric-scale shear zone that accommodated buckling of theorocline. Late Variscan lithospheric delamination and asthenospheric upwelling associated withbuckling in the core of the Cantabrian Orocline could explain the short-period high-temperatureregime in the Variscan segment of the Pyrenees