THE TECTONOMETAMORPHIC EVOLUTION OF THE GREATER HIMALAYAN SEQUENCE ALONG THE ZANSKAR SHEAR ZONE, NW INDIA

The Greater Himalayan Sequence (GHS) presents diachronous tectonometamorphic history of the Himalayas. In Zanskar region, it is possible to observe different metamorphic isograds at the surface due to the exhumation of the GHS rocks along the Zanskar Shear Zone (ZSZ). The samples collected from SE to N in Suru River Valley across these isograds provide significant information to constrain deformation mechanisms, temperatures, and strain rates of rocks within the ZSZ. The metamorphic mineral assemblage indicates increasing metamorphic grade from NE to SW and comprises Qz + Kfs + Pl + Bt + Ms ± Grt ± Sil ± Ky ± St ± Chl ± Tur ± Ru ± Zrn ± Opaque minerals. Garnet rotations, recrystallized quartz grains, irregular grain boundaries, kink bands, microfolds, and deformation bands suggest a variety of information regarding to the deformation based on the distance from the ZSZ. Using isochemical pressure-temperature phase modeling with Perplex, energy dispersive X-ray spectroscopy, electron backscatter diffraction, and with combining geo/thermochronology data from U-Pb, ⁴⁰Ar/³⁹Ar, and (U-Th)/He provide understanding the exhumation history of the GHS high-grade metamorphic rocks and the relationship to shearing on the ZSZ in addition to testing mid-crustal channel flow model explaining the emplacement of the GHS. A metamorphic pressure-temperature-time-deformation (P-T-t-d) history of the GHS rocks, generated in the light of these combining data using multi methods, is believed to fill gaps in data to understand tectonic and metamorphic evolution of the GHS metapelites, deformed within the ZSZ, in the Suru River Valley which has less-clarified evolutionary history compared to the eastern part of the GHS.