Abstract

Autochthonous sedimentary rocks on the Masirah Ophiolite preserve a record of vertical movements of their oceanic basement. The Masirah Ophiolite was formed in the uppermost Jurassic and subsequently underwent thermal subsidence for about 20 Ma as documented by pelagic sediments. Submarine alkali-basaltic volcanism in the lower Barremian marks the onset of rapid basement uplift to or above sea-level. Carbonate platforms grew in Barremian/mid-Aptian time on highs of oceanic basement. The uplift is interpreted as the result of transpressive tectonism along a large oceanic fracture zone. The platforms submerged in the mid-Aptian and reached the CCD in the Albian. Ribbon cherts were deposited during the Albian to Santonian time. The first influx of siliciclastic detritus, shed from the Arabian craton, is recorded in Coniacian sandstones. Ophiolitic conglomerates interfinger in the Campanian to mid-Maastrichtian with continent-derived sandstones, reflecting regional compressive tectonism. Crystalline exotics, deposited in the late Maastrichtian, are derived most likely from the Precambrian basement of Arabia, whilst the origin of the sedimentary exotics, dated Triassic to Cretaceous, remains unclear. The Masirah Ophiolite was overthrust at the Cretaceous–Tertiary boundary by an upper ophiolite nappe and emplaced onto the margin of southeast Oman.

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