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New geochemical Nd isotope and U-Pb zircon data from Neoproterozoic volcanic rocks from Wadi Sawawin in northwestern Saudi Arabia provide important constraints on the evolution of the crust in this part of the Arabian-Nubian Shield (ANS) The Ghawjah volcanic rocks range from tholentic to calc-alkaline and are metamorphosed to greenschist facies U-Pb zircon analyses for GhawJah andesite yield a weighted mean Pb-206/U-238 age of 763 +/- 25 Ma indicating that these are some of the oldest rocks of the Midyan terrane GhawJah volcanic rocks are mostly moderately fractionated as indicated by Mg-numbers between 28 and 67 Cr between 5 to 537 ppm and Ni from 4 to 175 ppm REE patterns are slightly fractionated [(La/Yb)N = 1 2 to 4 0] and multi-element diagrams show Ba Sr Rb and K enrichments and Nb and Ta depletions typical of modern convergent-margin igneous rocks GhawJah volcanic rocks have positive epsilon Nd (+5 4 to + 8 2) and a mean model age of 0 71 Ga GhawJah volcanic rocks are similar to the "Younger Volcanic rocks from the Central Eastern Desert (CED) of Egypt in terms of stratigraphic relations chemical compositions Nd-isotopic compositions and U-Pb zircon ages (similar to 750 Ma) indicating that both were generated by partial melting of subduction-modified depleted mantle The Ghawjah volcanic rocks are interpreted to have formed at similar to 750 Ma in an arc setting during an Important episode of crust formation (C) 2010 Elsevier B V All rights reserved