Sm-Nd dating of garnet granulites from the Kohistan complex, northern Pakistan

Sm-Nd mineral-isochron ages of garnet granulites in the southern part of the Kohistan complex are determined. The 91.0±6.3 Ma age is obtained from a granulite body of the Jijal complex at Pattan and the 69.5±9.3 Ma age is obtained from a granulite body of the Chilas complex at Zambil. These ages indicate that the granulite bodies at Pattan and at Zambil had cooled to below upper amphibolite facies by about 90 Ma and about 70 Ma respectively. The time of cooling of the granulite of the Jijal complex is comparable to the time-lapse of the Asia-Kohistan collision (102-75 Ma), although that of the Chilas complex is probably younger than the Asia-Kohistan collision and certainly older than the Asia-India collision (c. 50 Ma).