K-Ar biotite ages from Miocene post-collisional Garam Chashma leucogranite, eastern Hindukush Range (Trans-Himalayas), northwestern Pakistan

Abstract

Garam Chashma granitic rocks intrude discordantly into the Hindukush metamorphic complex on the southern margin of the Asian plate, Trans-Himalayas, northwestern Pakistan. The rocks are fine to coarse-grained, two-mica leucogranite. K-Ar biotite analyses of four samples from the Garam Chashma pluton yield 18-20 Ma ages. These ages are younger than those of the other post-collisional granitic rocks in Trans-Himalayas of Pakistan and resemble those of the Higher Himalayan granitic rocks.