Tectonics of the Masirah Fault Zone and eastern Oman

Abstract

Abstract Previously known but undescribed ophiolites on Ras Madrakah and Ras Jibsch and the ophiolite forming Masirah Island define an upthrust linear zone now separated from the Oman continental margin by the Masirah Fault. West of this, in the Batain coast, are the allochthonous Batain Melange and the Hawasina Complex of Mesozoic basinal deposits, mainly cherts. The Melange, like the Semail Melange with which it is correlated, contains ophiolite and Permian limestone exotics with Tethyan faunas. These allochthonous rocks are intensely deformed by WNW-vergent thrusts and folds. This Batain fold and thrust belt widens and becomes more complex northwards. It appears to have been continuous with the deformation south of the Semail Ophiolite, although now separated by the Jebel Ja’alan Uplift. The tectonics are intrepreted to be the result firstly of northward motion, along the Masirah Fault, of the Helmand Block of Afghanistan, away from the Oman continental coast, and during this motion, upthrust of the Masirah Ophiolite. Then, later in the Cretaceous, southwestward obduction of oceanic coast, including the Semail Ophiolite and the Masirah Ophiolite Zone, onto the Arabian continental plate. The oblique obduction across the NNE-trending Batain margin produced the Batain fold and thrust belt and reversed the strike-slip motion on the Masirah Fault.