Abstract
Ophiolites are key components of the Neoproterozoic Arabian-Nubian Shield (ANS). Understanding when they formed and were emplaced is crucial for understanding the evolution of the ANS because their ages tell when seafloor spreading and terrane accretion occurred. The Yanbu-Onib-Sol Hamed-Gerf-Allaqi-Heiani (YOSHGAH) suture and ophiolite belt can be traced similar to 600 km across the Nubian and Arabian shields. We report five new SHRIMP U-Pb zircon ages from igneous rocks along the Allaqi segment of the YOSHGAH suture in southernmost Egypt and use these data in conjunction with other age constraints to evaluate YOSHGAH suture evolution. Ophiolitic layered gabbro gave a concordia age of 730 +/- 6 Ma, and a metadacite from overlying arc-type metavolcanic rocks yielded a weighted mean Pb-206/U-238 age of 733 +/- 7 Ma, indicating ophiolite formation at similar to 730 Ma. Ophiolite emplacement is also constrained by intrusive bodies: a gabbro yielded a concordia age of 697 +/- 5 Ma, and a quartz-diorite yielded a concordia age of 709 +/- 4 Ma. Cessation of deformation is constrained by syn- to post-tectonic granite with a concordia age of 629 +/- 5 Ma. These new data, combined with published zircon ages for ophiolites and stitching plutons from the YOSHGAH suture zone, suggest a 2-stage evolution for the YOSHGAH ophiolite belt (similar to 810-780 Ma and similar to 730-750 Ma) and indicate that accretion between the Gabgaba-Gebeit-Hijaz terranes to the south and the SE Desert-Midyan terranes to the north occurred as early as 730 Ma and no later than 709 +/- 4 Ma. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.