The Leo Pargil dome, northwest India, is a 30 km‐wide, northeast‐trending structure that is cored by gneiss and mantled by amphibolite facies metamorphic rocks that are intruded by a leucogranite injection complex. Oppositely dipping, normal‐sense shear zones that accommodated orogen‐parallel extension within a convergent orogen bound the dome. The broadly distributed Leo Pargil shear zone defines the southwest flank of the dome and separates the dome from the metasedimentary and sedimentary rocks in the hanging wall to the west and south. Thermobarometry and in‐situ U–Th–Pb monazite geochronology were conducted on metamorphic rocks from within the dome and in the hanging wall. These data were combined with U–Th–Pb monazite geochronology of leucogranites from the injection complex to evaluate the relationship between metamorphism, crustal melting, and the onset of exhumation. Rocks within the dome and in the hanging wall contain garnet, kyanite, and staurolite porphyroblasts that record prograde Barrovian metamorphism during crustal thickening that reached ∼530–630 °C and ∼7–8 kbar, ending by c. 30 Ma. Cordierite and sillimanite overgrowths on Barrovian assemblages within the dome record dominantly top‐down‐to‐the‐west shearing during near‐isothermal decompression of the footwall rocks to ∼4 kbar by 23 Ma during an exhumation rate of 1.3 mm year−1. Monazite growth accompanied Barrovian metamorphism and decompression. The leucogranite injection complex within the dome initiated at 23 Ma and continued to 18 Ma. These data show that orogen‐parallel extension in this part of the Himalaya occurred earlier than previously documented (>16 Ma). Contemporaneous onset of near‐isothermal decompression, top‐down‐to‐the‐west shearing, and injection of the decompression‐driven leucogranite complex suggests that early crustal melting may have created a weakened crust that was proceeded by localization of strain and shear zone development. Exhumation along the shear zone accommodated decompression by 23 Ma in a kinematic setting that favoured orogen‐parallel extension.

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Mabja Dome, southern Tibet, exposes mid-crustal rocks proposed to have originated from a southward flowing mid-crustal channel. Kinematic, mean kinematic vorticity (W m), and metamorphic petrography analyses on these mid-crustal rocks were performed to test this hypothesis. Kinematic indicators show a transition with structural depth from top-north and top-south shear to solely top-south shear. Along the northernmost transects, W m in schists and orthogneisses range from 0.52-0.84 (63-36% pure shear). W m for quartzites ranges from 0.9-0.99 (27-1% pure shear). Deformation temperatures increase from ~450 °C in the chloritoid-zone to ~700 °C in the sillimanitezone and were recorded between ~35-16 Ma. These patterns exhibit a complex flow regime characterized by: (1) opposing shear sense driven by heterogeneous viscosity and/or channel thickness, (2) broad top-south shear along the Main Central Thrust, (3) simple shear partitioned into weaker quartzite horizons, and (4) an increase in lithostatic load with depth. iv ACKNOWLEDGMENTS I received assistance from many helpful people and organizations while working on this project. Funding was provided by generous grants from the Geological Society of America, CWU Department of Graduate Studies, and Sigma Xi. Additional funding for travel to conferences in order to present this work was provided by the CWU Department of Geological Sciences, the CWU Department of Graduate Studies, and Jeffrey Lee. I wish to thank my committee members Wendy Bohrson and Charlie Rubin for their input and support of my research. Of course, I must thank my advisor Jeffrey Lee for his exceptional guidance and support while working on this project. Thanks to Bradley Hacker and Gareth Seward for their collaboration and the use of their facilities at the

Building of the Himalaya and Tibetan Plateau involved an interplay between crustal thickening and extension. The NW Indian Himalaya near the Leo Pargil dome contains approximately N trending brittle normal faults and NE trending normal-sense shear zones (i.e., bounding Leo Pargil dome) between the South Tibetan detachment system to the south and the Karakoram fault to the north. The Leo Pargil shear zone bounds the southwest flank of the Leo Pargil dome. Estimates of deformation temperatures and mean kinematic vorticity (W m ) from the shear zone were integrated with pressure-temperature estimates to evaluate its kinematic and thermal evolution. Oblique quartz fabrics yielded kinematic vorticity estimates indicating that the rocks within the shear zone were thinned by up to 62% during W directed shearing. Top-down-to-the-W ductile deformation is recorded at temperatures from >650°C at the deepest structural levels within the dome and from 400 to 500°C at shallower structural depths. Hanging wall rocks record much lower temperatures. Pressure-temperature data indicate that rocks in the dome were exhumed from depths of~36 to 22 km. In contrast to other mechanisms proposed for dome formation across the Himalaya, initiation of ductile movement on the Leo Pargil shear zone occurred at midcrustal levels in a region of localized synconvergent extension at >23 Ma. The timing and kinematic setting of deformation on the Leo Pargil shear zone suggest that exhumation could be related to a localized zone of transtension near the Karakoram fault zone.