--> Abstract: Backthrusting and Reverse Faulting Along the Western Margin of the Semail Ophiolite in the Al Wadiyein Area, Buraimi, Oman, by Jim Leanderson, Mohammed Y. Ali, and James Small; #90077 (2008)

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Backthrusting and Reverse Faulting Along the Western Margin of the Semail Ophiolite in the Al Wadiyein Area, Buraimi, Oman

Jim Leanderson*, Mohammed Y. Ali, and James Small
The Petroleum Institute, UAE
*[email protected]

A north-south range of peridotite hills lies in the center of Al Wadiyein. To the west are NS-trending hills of Hawasina carbonates, whereas the Kawr Group limestone is exposed on a ridge to the north. Gravity and seismic surveys (Ali et al., 2006) revealed that the contact between the ophiolite and the Hawasina carbonates is a buried, east-dipping reverse fault. The survey also revealed that the Hawasina carbonates overlie the ophiolite along a shallow, west-dipping contact that lies on strike with a shallow, west-dipping thrust fault, 1.5 km north of the geophysical survey lines. At this location, a nappe of the Kawr Group limestone was backthrust over the ophiolite, with locally up to three thrust slices of gabbro, and Kawr Group limestone at the base, each approximately two to three meters thick. A moderate to steep east-dipping, NS-striking shear zone, one km east of the reverse fault, cuts the underlying peridotite and the backthrust. The shear zone has the same strike and dip as the reverse fault. It is concluded that backthrusting of the Kawr Group limestone and Hawasina carbonates over the ophiolite was followed by reverse faulting. These events may mark the latter stages of obduction of the ophiolite in response to the cessation of westward displacement of the allocthonous carbonate sequences. The termination of the ophiolite along the reverse fault at a shallow depth suggests that the ophiolite may extend farther to the west at depth in the Wadiyein area.

 

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain