Unravelling the Tectonic History of the Oman Mountains Using Structural Restoration in the Emirate of Sharjah, UAE

Abstract

The world-class outcrops of the MusandamPeninsula and Northern Oman Mountains have given valuable insight into the geological setting, history and genesis of the fold and thrust belt in the northern United Arab Emirates. This paper provides new insight into the tectonic evolution of the Northern Oman Mountains in the Emirate of Sharjah using state-of-the-art 3D seismic and reprocessed legacy 2D seismic via structural restoration. Seismic interpretation has revealed that two thrust systems exist in the subsurface separated by a detachment which lies in Upper Cretaceous strata. A deep thrust system forms at Arabian Platform level (Lower Cretaceous and older) and a shallower thrust system within the Aruma Group (Upper Cretaceous and younger) is present as well. Throughout much of the thrust belt in Sharjah, the Aruma Group subcrops beneath the desert and outcrops along narrow ridges that protrude from it at present day. The thrust front is characterised by a series of en echelon pop-up structures which form a north-south trend across the Emirate. It is proposed that these transpressional features formed along pre-existing north-south trending lineaments. These are the most prospective hydrocarbon traps in the Northern Emirates and include the Sajaa, Moveiyed, Kahaif, Mahani, and Margham gas-condensate fields. The area has been through a series of tectonic events, related to extension in the Permian, tectonic quiescence throughout much of the Mesozoic, an ophiolite obduction event in the late Cretaceous, and in line with the general view, a second compressional event in the Miocene related to the Zagros Orogeny. In the Miocene, the thrust front pop-up structures acted as buttresses and prevented the westward movement of the shallow thrust belt within the Aruma Group, which led to duplexing and intense imbrication to the east of the thrust front and to the west of the encroaching Semail Ophiolite. The interrelationships between these events, stratigraphy, and basin evolution are discussed in this paper with a view to unravelling the tectonic history of the Northern Oman Mountains.