Structure of the Jebel Sumeini-Jebel Ghawil area, Northern Oman

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Abstract
Detailed structural mapping of the Sumeini half-window, Jebel Sumeini and Jebel Ghawil areas in northern Oman, shows that the dominant Late Cretaceous thrusting was a WSW-propagating piggy-back sequence modified by late-stage, deeper level thrusts in the Sumeini slope facies carbonates which breached up into the overlying Hamrat Duru thrust sheets. The uppermost Semail thrust carrying the complete ophiolite sequence overlaps lower Haybi thrust sheets and inverted metamorphic isograds are displayed in the footwall. Amphibolites and greenschists of the metamorphic sole have been subsequently imbricated with Haybi alkaline and tholeiitic volcanics, Triassic Oman exotic limestones and melanges of the Haybi duplex. A major E-W trending lateral ramp is inferred along the southern edge of Jebel Ghawil downthrowing the Sharm peridotite block up to 1000 m to the south. The basal Hamrat Duru thrust overlies Cretaceous Mayhah Formation slope facies carbonates and has been folded around the lower, later culminations primarily of Late Cretaceous age, enhanced by further structural growth and short-distance post-Maastrichtian (? Eocene) thrusting. Thrusts at the base of the Sumeini Group have breached through the overlying Hamrat Duru sheets and locally overthrust Maastrichtian Faiyah Formation limetones along the SW margin of Jebel Wasa. Culmination of Jebel Sumeini promoted hanging-wall drop fault development along the trailing (NE) edge of the Sumeini duplex, down-faulting Hamrat Duru rocks to the east. The amount of displacement of the Jebel Sumeini culmination increases towards the south, toward the axis of the Sumeini half-window.