Higher Himalayan Shear Zone, Sutlej section: structural geology and extrusion mechanism by various combinations of simple shear, pure shear and channel flow in shifting modes

摘要: The Higher Himalayan Shear Zone (HHSZ) in the Sutlej section reveals (1) top-to-SW ductile shearing, (2) top-to-NE shearing upper- and lower strands of South Tibetan Detachment System (STDSU, STDSL), (3) brittle corroborated by trapezoid-shaped minerals micro-scale. In proposed extrusion model HHSZ, E1-phase during 25–19 Ma is marked simple upper sub-channel defined strand Main Central Thrust (MCTU) top STDSU as lower- boundaries, respectively. Subsequently, E2a-pulse 15–14 was characterized shear, pure channel flow entire HHSZ. Finally, E2b-pulse 14–12 observed (MCTL) STDSL explains constraints thicknesses along with spatially variable rate inverted metamorphism predicts shear strain after to be maximum at boundaries which crudely matches existing data. other speculations that cannot checked are uniform from MCTU HHSZ E1-phase; fastest rates E2a- E2b-pulses, respectively; (4) thickness rare absence STDSU. Non-parabolic fabrics possibly indicate heterogeneous strain. around 12 augmented extruded rocks arrive a shallower depth. brittle–ductile extension leading boudinage did not enhance extrusion.