LATE CENOZOIC PARTITIONING OF OBLIQUE PLATE CONVERGENCE IN THE ZAGROS FOLD-AND-THRUST BELT (IRAN)

Abstract

The NW trending Zagros fold-and-thrust belt is affected by two major dextral faults: (1) the NW trending Main Recent Fault that accommodates partitioning of oblique convergence at the rear of the western Zagros and (2) the north trending Kazerun Fault located in the central Zagros. Combined structural and fault kinematics studies and SPOT images analysis have shown a Pliocene kinematic change accompanied by a fault pattern reorganization, which has led to a modification in the accommodation of oblique convergence. Since the late Pliocene, the distributed transpressional deformation operating at the rear of the belt has become partitioned along the newly formed Main Recent Fault. This fault cuts through early Pliocene nappes and transpressional structures by right-laterally reactivating high-angle thrusts. The southeastern termination of the Main Recent Fault connects to the northern termination of Kazerun Fault that consists of three fault zones that end in bent, orogen-parallel splay thrust faults. The Kazerun Fault, together with a series of north to NNW trending inherited basement strike-slip faults, define an orogen-scale fan-shaped fault pattern pointing toward the Main Recent Fault-Kazerun Fault junction. This structural pattern allows slip from along the Main Recent Fault to become distributed by transfer to the longitudinal thrust faults and folds of the Zagros belt, with the fans-haped fault pattern acting as a horse-tail termination of the Main Recent Fault. Copyright 2006 by the American Geophysical Union.