Origin of pseudotachylites in slow creep experiments

We conducted a series of experiments on granitoid cataclasites under mid-crustal conditions (Pc∼500 MPa, T=300 °C) and slow displacement rates (10−8 ms−1

► Localized deformation in experimental fault rocks produces fragment loaded amorphous material at slow velocities. ► Nanocrystalline partly amorphous material is a precursor material for the amorphous material. ► Amorphous material shares micro- and nano-structural characteristics with natural pseudotachylites