Fig. 8
From: Lower-crustal earthquakes in southern Tibet are linked to eclogitization of dry metastable granulite
Organization of fault zones in samples deformed at 1073 K. a, b D1996 (G sample). a Wide-spread intra-grain ruptures. Red, blue, and white arrows mark intra-grain ruptures in Cpx, Plg, and Qtz, respectively. These ruptures are connected by thin NRBs to form larger, complex shear zones. b Formation of larger fault zones. Shear and ruptures developed along several directions, which can be interpreted as Riedel shears52. Y shears (solid white line; parallel to the main shear zone) dominate the microstructure, characterized by long and continuous NRBs cutting through multiple grains (delineated by white arrows). R and P shears are ~±30° from the Y shears (light green and red dashed lines and arrows). R′ and X shears are ~±60° from the Y shears (yellow and blue dashed lines and arrows). R and R′ shears are less well developed and commonly associated with microfractures. c, d D1787 (EG sample). c Wide-spread eclogitization reaction along grain boundaries and within Plg grains. Numerous reaction bands terminate within the Plg grains, along the NW-SE (white arrows). These reaction bands typically initiate from grain-grain contacts, suggesting a stress assisted reaction. Indicated in between the two opposing red arrows is a complex shear zone with multiple subparallel NRBs. Compared to D1996, D1787 contains numerous small voids along grain boundaries. These voids may be cavities caused by the large volume reduction of the reaction, although we cannot completely rule out the possibility of small grains popping off during polish. d A large shear band consisting of reaction products cutting through multiple grains with different mineralogy (delineated by white arrows that are nearly perpendicular to the band
