Rapid early Miocene exhumation of the Ladakh batholith, western Himalaya

Abstract

Zircon, apatite (U-Th)/He, and apatite fission-track age data record a rapid cooling event in the Ladakh batholith of northwest India ca. 22 Ma. A combination of inverse and forward modeling of the data confirms this qualitative interpretation. Combining the thermochronometric data with structural evidence, we propose that exhumation was due to south-directed thrusting of the batholith along a north-dipping structure, coupled with erosion to bring the rocks to the surface. The rapid exhumation recorded in Ladakh is contemporaneous with exhumation of the High Himalaya. This focused surface denudation and structural shortening north of the Indus suture zone in early Miocene time implies that the actively deforming and eroding Himalayan thrust wedge extended farther north than channel flow models currently predict. © 2006 Geological Society of America.