| Abstract: | The Kohistan Arc Complex is an integral part of the NW Himalayan collision system and is bounded by two major suture zones, the Indus Suture Zone (ISZ) and the Northern Suture in the south and north respectively. Fission‐track analyses on samples collected along the Indus River across the arcuated ISZ in the Besham region are presented here. The footwall yields zircon and apatite fission‐track (FT) ages of ∼23 Ma and ∼3.7 Ma respectively; the hanging wall ages range from 24 to 42 Ma for zircon and ∼10 Ma for apatite. Thus, the change in ISZ kinematics from thrusting to normal faulting was not later than Oligocene and normal faulting on this ISZ segment was still active at least into early Pliocene times. At this time normal faulting had already ended at other ISZ segments, but it was still (or again) active across the ISZ in the Besham region most likely as a local phenomenon caused by the growth of the Indus Syntaxis, a transverse antiform parallel to the Nanga Parbat Syntaxis. |
