Back-thrust Origin of the Hafit Structure, Northern Oman Mountain Front, United Arab Emirates

Abstract

ABSTRACT The Tertiary structures of the Northern Oman Mountains are marked by a discontinuous belt of jebels peripheral to their western margin. Detailed field mapping of the northern Hafit structure in the Northern Oman Mountains indicates that the structures consist of two en echelon anticlines, the main Hafit Anticline to the south, and the Al-Ain Anticline to the north. Both anticlines are related to the same deformation event. Structural analysis, using geometric balancing techniques suggests that the Hafit structure developed over a west-vergent basal thrust. The depth to detachment of the thrust indicates that the basal detachment occurs at different stratigraphic positions and progressively increases northward, while the magnitude of deformation increases southward. The thrust wedges back to the east and propagated upward through the structure during a major Tertiary deformational event resulting in an east-vergent, fault-propagation fold. The recent interpretation that the Hafit structure grew as a detachment fold above a basal decollement and synchronously with sedimentation, is at variance with structural evidence from the Hafit area. It is believed that the Hafit structure formed after the Miocene time.