New Insights in the Tectonostratigraphic evolution of the Oman Emirates Thrust Belt; the Key Role of the Jebel Hafit Structure
Authors: van Dijk Janpieter 
Published: November 2020

Jebel Hafit is situated along the border of Oman and the UAE near the city of El Ain, and was subject to numerous studies. It is a key analogue of some of the hydrocarbon producing subsurface structures of the Emirates and an important element for the reconstruction of the evolution of the Oman-UAE Thrust Belt.

We conducted an integration of detailed multiscale remote sensing study, a review of available surface/subsurface data, and our own field geological surveys, and propose a new revised stratigraphic framework which resolves some of the previously raised perplexities, and a new view on the structural evolution of the thrust belt.

According to our reconstruction Jebel Hafit is a steep and narrow, elongated, sigmoidally shaped asymmetrical anticline, which stratigraphy shows an Eocene-Oligocene series starting from thick bedded shallow marine carbonate platform (Rus Fm), developing into an instable slope (megaslumps and bioclastic turbidite series),deepening into a carbonate shelf (distal turbidites and cherty limestones) (Dammam Fm). Part of this series was in a later stage diagenetically dolomitised. The complex structural setting results in difficulties in the reconstruction, being topographically and structurally inverted along faults which obliquely cross the anticline.

Combining all available data we propose a new solution according to which the structure of Jebel Hafit and similar anticlines is directly linked to deep seated transpressional faulting, instead of related to folding and back-thrusting along low angle thrusting which characterises, instead, the older portion of the Oman-Emirates thrust belt.

In our new regional model, the thrust belt displays an evolution from thin-skinned to thick skinned tectonics, starting from Cretaceous up to Present day. In Late Cretaceous times, the area was characterised by the thin-skinned over thrusting of ophiolites and basinal carbonate series towards the southwest and was with the Makran Range part of one accretionary thrust wedge, which extended from Pakistan up to the southern area of Oman. This external part of the thrust belt was sealed by the Maastrichtian-Paleocene-Eocene deposits and became part of the Miocene foreland Basin (extension of the Zagros Basin). This Basin became deformed, during Plio-Pleistocene times, along a major NNE-SSW trending dextral thick-skinned thrust belt comprising the present day Musandam-Emirates-Oman mountain belt, along the SE- border of the north-eastern moving Arabian Plate. The low angle contacts and unconformities of Late Cretaceous up the Miocene times have been deformed by these pulsating progressive movements which were responsible for the transpressional structures like Jebel Hafit, at the frontal zone of this thrust belt.

Our analyses show that the complexities observed in the surface and the subsurface can be fit into one comprehensive model which incorporates, though, different tectonic styles, and unites the information available for the various geographical areas into one uniform model.