Structural evolution of the Suneinah Foreland, Central Oman Mountains

Abstract

Abstract In the early Mesozoic, the Suneinah Foreland of the central Oman Mountains lay on the flank of a north facing Tethyan rift margin. By the end of the Middle Cretaceous, this had evolved into a carbonate dominated passive margin. Following regional uplift and erosion during the Turonian, it was downwarped, faulted and buried by a deeper water shale facies. At the beginning of the Campanian, the earlier Tethyan sea floor and continental rise prism were rapidly telescoped across the margin, loading and downflexing the crust to form the narrow Suneinah Foredeep and peripheral bulge beyond. By the end of the Cretaceous this foredeep had been filled with marls and coarse detritus shed from the adjacent allochthon, and during the Early Tertiary a transgression swept across and blanketed much of the eroded nappe surface. In the Late Oligocene-Middle Miocene the Arabian plate began to separate from Africa and move northeast towards the Eurasian crustal collage. The Musandam promontory acted as a spur or indentor on this advancing plate, focussing compression and transmitting it back along deep basement fractures in the old Tethyan rift domain. Intense transpressional deformation inverted the entire margin to form the modern Oman Mountains and a new foredeep along its western flank. Reactivated Mesozoic fault blocks fringing the inversion orogen in the Suneinah area, deformed fairly rigidly, but the more plastic Late Cretaceous and Tertiary section above was squeezed into sometimes quite spectacular high amplitude folds. With the onset of sea floor spreading in the Red Sea/Gulf of Aden and northerly movement of the Arabian plate along the Dead Sea transform during the Late Miocene-Pleistocene, tectonic intensity waned in the Oman Mountains and much of its earlier sedimentary cover was stripped off.