Crustal reworking at Nanga Parbat, Pakistan: Metamorphic consequences of thermal-mechanical coupling facilitated by erosion

Within the syntaxial bends of the India-Asia collision the Himalaya termina te abruptly in a pair of metamorphic massifs. Nanga Parbat in the west and Namche Barwa in the cast are actively deforming antiformal domes which expo se Quaternary metamorphic rocks and granites. The massifs are transected by major Himalayan rivers (Indus and Tsangpo) and are loci of deep and rapid exhumation. On the basis of velocity and attenuation tomography and microse ismic, magnetotelluric, geochronological, petrological, structural, and geo morphic data we have collected at Nanga Parbat we propose a model in which this intense metamorphic and structural reworking of crustal lithosphere is a consequence of strain focusing caused by significant erosion within deep gorges cut by the Indus and Tsangpo as these rivers turn sharply toward th e foreland and exit their host syntaxes. The localization of this phenomeno n at the terminations of the Himalayan arc owes its origin to both regional and local feedbacks between erosion and tectonics.