“Oman Exotics”—Oceanic carbonate build-ups associated with the early stages of continental rifting

Abstract

The so-called “Oman Exotic” limestones form isolated masses, from boulder size to 1,000 m thick, of Middle to Upper Permian and Upper Triassic fossiliferous limestones, and crop out within imbricated thrust slices beneath the Semail ophiolite in the Oman Mountains. Permian Exotics are of dominantly reef and forereef facies, whereas Triassic Exotics are more typically of back-reef and lagoonal facies. They are commonly associated with a substrate of alkalic and transitional tholeiitic basalts and are interpreted as a series of reef-associated carbonate buildups deposited in part on oceanic islands or seamounts, close to the site of initial rifting of the Oman continental margin.