New zircon U-Pb age data and geochemistry for the Sa'al metamorphic complex (SMC) in Sinai (Egypt) provide the first robust evidence of latest Mesoproterozoic island arc rocks at the northernmost Arabian-Nubian Shield, possibly indicating that formation of the shield commenced prior to 870 Ma. An older series of calc-alkaline volcanic and intrusive rocks yielded ages of ca. 1.03-1.02 Ga. Zircon xenocrysts within these rocks attest to arc magmatism predating the SMC by ~80 m.y., as well as the minor contribution of Paleoproterozoic crust. Detrital zircons of the SMC pelites exhibit textural and U-Pb age patterns supporting their derivation from the volcanic rocks as arc detritus. A ca. 820 Ma gneissic pluton intruding the SMC indicates that by Cryogenian time, the SMC was already incorporated within the evolving Arabian-Nubian Shield. The 1.0-1.1 Ga SMC rocks provide a possible connection between latest Mesoproterozoic ocean closure during the assembly of Rodinia and the later buildup of Gondwana. There is growing indication, including the findings of this study, that 1.0-1.1 Ga crust composed a more significant component in northernmost Gondwana than hitherto recognized.
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