Recumbent folding in the Upper Cretaceous Eaux?Chaudes massif: A Helvetic?type nappe in the Pyrenees?

We describe a singular structure in Upper Cretaceous rocks of the Eaux-Chaudes massif western Pyrenees, consisting kilometre-scale fold nappe with sheared overturned limb. High ductile strain attests deformation style rarely reported for alpine and peak temperature carbonates is estimated by Raman spectroscopy carbonaceous material palaeothermometry lower greenschist facies (>300°C). The normal limb retains original sedimentary textures, while shows calcite crystal-plastic dynamic recrystallization, crystallographic preferred orientation. observed ductility metamorphic bear similarities Helvetic nappes Alps, suggesting deep burial and/or possibly high geothermal gradient this part Pyrenees.