Jurassic evolution of the Arabian carbonate platform edge in the central Oman Mountains

International audienceThe Jurassic Sahtan Group exposed in northern Oman was deposited in shallow marine environments at the edge of the Arabian Platform facing the Neo-Tethys (Hamrat Duru Basin). The upper Sahtan Group is made up of a mixed siliciclastic–carbonate unit overlain by pure carbonate deposits, assigned to a Bathonian and Early Callovian age on the basis of brachiopods and foraminifers. These carbonate depositional systems were composed of outer oolitic shoals that underwent subaerial exposure, and a deeper, somewhat restricted, gently dipping shelf interior. Oolitic material was shed off the platform edge into the deep-sea depositional complex of the Guweyza Formation. The Sahtan Group is affected by an important thickness reduction towards northeastern Jabal Akhdar. The angular unconformity (0.2%) at the top of the Sahtan Group is shown to result from tilting and top truncation of genetic sequences. This unconformity is overlain by the Rayda Formation, a veneer that shows an onlap pattern including a gradual deepening upwards facies evolution. The minimal time span of the stratigraphic hiatus is Mid-Callovian–Kimmeridgian. Oxfordian and Kimmeridgian sequences were probably never deposited in this area because of lack of accommodation space and/or because of subaerial exposure. It is proposed herein that the unconformity was shaped by subaerial carbonate dissolution during a steady, tectonically driven exhumation of the platform edge. During the Tithonian, a major eustatic sea-level rise caused transgression of the Rayda Formation upon the platform edge and normal shelf marine conditions resumed in the eastern Arabian Peninsula