An early Miocene age for a high-temperature event in gneisses from Zabargad Island (Red Sea, Egypt): mantle diapirism?

U-Pb zircon data from a felsic gneiss located at the contact zone with the central peridotite body of Zabargad Island (Red Sea, Egypt) provide an age of 23.2 +/- 5.9 Myr consistent with the U-238-Pb-206 age of the youngest co ncordant grain (22.4 +/- 1.3 Myr). Concordant grains indicate new zircon gr owth and for resetting whereas slightly discordant analyses suggest partici pation of an older zircon component whose age cannot be defined precisely. SEM hack-scattered imaging further reveals the occurrence of zoned domains almost completely erased by complex internal structures attributed to exten sive recrystallization lander metamorphic conditions. The 22.4 Myr Miocene age is thus interpreted as dating a high-temperature metamorphic event. The proximity between the studied sample and the peridotite supports previous conclusions which regard parts of the peridotites from Zabargad island as a n asthenopheric mantle diapir which intruded the thinned Pan-African contin ental crust during the early stages of the Red Sea opening.