Warren, Clare J.; Parrish, Randall R.; Searle, Michael P. and Waters, David J.
Dating the subduction of the Arabian continental margin beneath the Semail ophiolite, Oman.
The presence of high-pressure (P) eclogites along the northeast margin of the Arabian continental plate beneath the Semail ophiolite demonstrates that subduction of thinned continental crust to pressures of 20 kbar (80 km depth) has occurred. Current debate centers on whether this high-P metamorphism occurred prior to, during, or following ophiolite emplacement, which is known to have started ca. 95–93 Ma. Five concordant U-Pb zircon ages from a garnet-clinopyroxene-phengite-crossite eclogite from As Sifah, northeast Oman, precisely constrain the age of high-P metamorphism at 79.1 ± 0.3 Ma. This age demonstrates that high-P metamorphism occurred during continental subduction 15 m.y. after formation of the ocean floor that subsequently became the Semail ophiolite.
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