Rapid Pliocene exhumation in the Karakoram (Pakistan), revealed by fission-track thermochronology of the K2 gneiss

Rapid Pliocene denudation in the Karakoram, Pakistan, as revealed by fission- track dating of rocks from K2 (Godwin Austen) was probably caused by tectonic uplift. Apatite separated from samples collected from elevations of 5300 to 8611 yielded fission-track ages of 2.1 ±0.6 to 4.3 ±1.4 Ma, and suggest an initial, apparent denudation rate of 3-6 mm/yr commencing after 5 Ma. One zircon separate from 6600 m gave a mean fission-track age of 32 ±6 Ma. The mid- Tertiary zircon age. delimits the maximum amount of Pliocene denudation to ≤7000 m. The total amount of denudation at the present mean surface elevation of ∼6000 m was estimated to be ∼6000 m.