The lenticular layer of the crust-mantle detachment exposed at Col d’Urdach and close to Bilatre (see Fig. 4 for location). A. Shear bands with white layers of serpentine minerals above the “ball trap”. B. Tectonic lenses in the Col d’Urdach quarry. C. Gouge and tectonic breccia along a subvertical fault zone in the Col d’Urdach quarry. D. Calcite crystallization on a fault surface (Bilatre quarry entry). E. Fault zone in the Bilatre quarry. F. Tip of a tectonic lens showing the transition from carbonate-free to carbonated serpentinized mantle (Bilatre quarry). G. Ophicalcite of the Bilatre quarry showing at least two generation of calcite veins (V1, V2). H. Tectonic fabric in the lenticular layer enhanced by anatomozed calcite veins (loose block near Bilatre). I. Phacoidal fabric in a large olistolith of the Urdach breccia (Bilatre).

La zone lenticulaire du détachement croûte-manteau au Col d’Urdach et à Bilatre (vues de terrain).