The Architecture of the South-Western Sector of the Dibba Zone at Jebal AlQamar (UAE)

Abstract

Jebal AlQamar (J. Qamar) Permian–Triassic highly recrystallized limestone, exposing SW of Dibba Zone in Northern UAE, is one of the Oman Exotic Blocks that originated as a structural high horst prior to Late Triassic during the rifting of NE Oman Passive Margin. The exotic block displays unique features, in the way that it settles on top of a Palaeozoic basement, unlike the oceanic seamount substrates of other Oman exotics. The area near J. Qamar is structurally complicated due to the uncertainty of the nature of the various lithological boundaries. The primary aim of this study is to explore these relationships studying the type of geological contacts. Field data were collected and plotted into an original GIS database. The key findings unravel the structural framework of J. Qamar blocks and its relationships with neighboring units, shedding light on their evolution. The geological architecture of the area demonstrates that, locally, the basement units (Semail Ophiolite and its metamorphic sole) and the exotic J. Qamar limestone, were possibly involved in the southwestward subduction zone during Late Cretaceous. J. Qamar exotic limestone was emplaced onto the Shamal Chert Fm. During exhumation, the system reached shallower depths along the subduction zone (~ 15km) in a transitional ductile – brittle phase, where some cohesive fault rocks (i.e., cataclasite) started to form. The preserved structures in the units provided guidance in distinguishing between folds, fractures, and faults that occurred during the brittle phase of Semail Ophiolite (directed-SW) and those induced by Hegab Thrust during the Late Oligocene (directed-NW).

Date of Award	Apr 2023
Original language	American English
Supervisor	Alessandro Decarlis (Supervisor)