Abstract
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 238U–206Pb age of the youngest concordant grain (22.4 ± 1.3 Myr). Concordant grains indicate new zircon growth and/or resetting whereas slightly discordant analyses suggest participation of an older zircon component whose age cannot be defined precisely. SEM back‐scattered imaging further reveals the occurrence of zoned domains almost completely erased by complex internal structures attributed to extensive recrystallization under 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 an asthenopheric mantle diapir which intruded the thinned Pan‐African continental crust during the early stages of the Red Sea opening.
Highlights
Much attention has been focused on the tectonothermal and geochemical evolution of rocks outcropping on Zabargad Island (Red Sea, Egypt)
Since the first work of Bonatti et al (1981), genetic models have been limited by the the scant data on the timing of juxtaposition between the peridotites and the gneisses, as well as the nature of the mafic/ultramafic rocks
One interpretation considers the peridotites as an asthenospheric mantle diapir intruding a Pan-African continental crust during the early stages of the Red Sea opening (e.g. Nicolas et al, 1987)
Summary
Much attention has been focused on the tectonothermal and geochemical evolution of rocks outcropping on Zabargad Island (Red Sea, Egypt). Pan-African ages for the metamorphic gneiss complex are well established by Sm±Nd and Rb±Sr mineral isochrons (Lancelot and Bosch, 1991; Brueckner et al, 1995) as well as by a zircon Pb±Pb evaporation date (Brueckner et al, 1995) from a felsic gneiss located a few hundred metres from the contact zone, between the central peridotite body and the gneisses.
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