Complex Tectonic History of Al-Yutamah Dome Area within Hijaz Terrane, Arabian Shield, South of Al Madinah, Saudi Arabia

Abstract

This paper documents the Al-Yutamah tectonic dome, located in the northwestern part of the Arabian Shield, Saudi Arabia. A new Infracambrian over-thrust fault zone is mapped, which superpose the Late Proterozoic rocks in the area. Kinematic indicators suggest top-to-the-south movements along this fault, mainly compressional and some extensional in nature. The area experienced several tectonic events that resulted in to a complex dome like structure formation with a surface area of 2050 km 2. The S 1 cleavages, which have been determined as the oldest structural features in the area, are attributed to (D 1) tectonic event along the Labunah Thrust Fault. This event was followed by another deformational event (D 2) that produced N-S trending F 2 folds in the area. The third deformational event (D 3) observed in the area is the brittle high-angle reverse faults, which generally dip toward north and south, suggesting compressional nature of the event. Fourth deformational event (D 4) in the area resulted in the formation of E-W trending F 4 folding, which occurred subsequent to the development of Najd Strike-slip Faulting and F 2 folding. Superposition of the F 2 and F 4 folds in the area developed a complex structural feature in the shape of Al-Yutamah dome. Overthrusting of the meta-sedimentary rocks as a result of movement along the Al-Yutamah fault is considered as a fifth tectonic event (D 5). The Al-Yutamah over-thrust fault is most likely late Infracambrian in age, which is associated with the Najd Strike-slip Fault zone. The Cenozoic listric faulting that probably exhumed the dome is considered as a sixth deformational event (D 6) in the area. During the Cenozoic, cross-cut faults developed in the dome by high-angle normal faulting that dissected it into different segments.