Tectonics of Nanga Parbat, western Himalaya: Synkinematic plutonism within the doubly vergent shear zones of a crustal-scale pop-up structure

Detailed mapping and geochronologic investigations from the eastern, southern, and western Nanga Parbat–Haramosh massif reveal two thrust-displacement shear zones that have a spatial and temporal link with granite plutonism from ca. 10 to 1 Ma. The shear zones define a crustal-scale antiformal pop-up structure, with dominant west-northwest–vergent and subordinate east-southeast–vergent thrusting. This is substantially different than the surrounding area where the main exposed Himalayan structures are oriented parallel to the orogenic trend and are early to middle Miocene or older. Structures mapped throughout Nanga Parbat demonstrate that its rapid and young exhumation is not due to orogen-scale structural unroofing, and that sustained high erosion rates are required. The observed west-northwest–directed shortening is proposed to be a result of differential arc-parallel motion accommodated at the syntaxial bend of the northwest Himalaya.