AR-40 AR-39 DATING OF THE EMPLACEMENT OF THE MUSLIM-BAGH OPHIOLITE, PAKISTAN/

The obduction-related basal part of the Muslim Bagh ophiolite (Baluchi stan, Pakistan) and the underlying metamorphic sequence were studied s tructurally which demonstrated a WSW-ENE-trending thrusting sequence f or the initial obduction. Ar-40/Ar-39 measurements on amphiboles and p lagioclase from the subophiolitic metamorphic rocks, and on plasticall y deformed and recrystallized dolerite samples from the base of the sh eeted dyke complex give apparent ages between 70.7 +/- 5.0 and 65.1 +/ - 4.1 Ma interpreted as cooling ages dating approximately the formatio n of the plastic deformation and obduction. The results indicate that the Muslim Bagh ophiolite represents a segment of ocean floor from the small and slow-spreading ocean branch of the Neo-Tethys located betwe en the Indo-Pakistani and the Afro-Arabian plates. The WSW-ENE-oriente d obduction of the Muslim Bagh ophiolite onto the Indo-Pakistani conti nental margin occurred with the convergence of the Neo-Tethys branch d uring the Late Cretaceous and before the Tertiary collision of the Ind o-Pakistani plate with the Eurasian plate.