Fig. 7: Nanostructures of sample WGN03.
a Overview image, taken in high-angle-annular dark-field (HAADF) mode, showing the nanostructure of the first focused-ion beam (FIB) section cut from sample WGN03 (dry dynamic; peak slip rate ≫ 1.5 mm/s; Fig. 2h). The white rectangle marks the location of the image shown in b, which was taken in bright field (BF) mode. There is little indication that the fault gouge material is crystalline. Numerous euhedral crystals, appearing brighter in HAADF mode (a) or darker in BF mode (b) than the remaining material, were identified as magnetite using the selected area electron diffraction (SAED) pattern II together with the chemical information obtained through element distribution maps (c).
