Multi-isotope study including whole-rock NdSr, single zircon Hf, and SIMS d 18 O analyses of zircons sheds light on magma sources in the northernmost Arabian-Nubian Shield (ANS) during *820-570 Ma. Reconnaissance initial Nd and Sr isotope data for the older rocks (*820-740 Ma) reaffirms previous estimates that early crustal evolution in this part of the shield involved some crustal contamination by pre-ANS material. Prominent isotope provinciality is displayed by post-collisional calc-alkaline and alkaline igneous rocks of *635-570 Ma across a NW-SE transect across basement of the Sinai Peninsula (Egypt) and southern Israel. Silicic rocks of the NW-region are characterized by lower eNd(T)-eHf(T) and higher Sr i and d 18 O compared with rocks of the SE-region, and the transition between the regions is gradual. Within each region isotope ratios are independent of the extent of magma fractionation, and zircon cores and rims yield similar d 18 O values. Comparison with southern segments of the ANS shows that the source for most *635-570 Ma rocks can be modeled as the isotopically aged lowerintermediate crust in the ANS core (SE-region) and its northern, more contaminated ANS margins (NW-region). Nevertheless, Nd-Sr isotope enrichment of the lithospheric mantle is indicated by some basic magmas of the NWregion displaying the most enriched Nd-Sr isotope compositions. Comparison of Nd and Hf depleted mantle model ages for rocks of the SE-region may indicate that crustal formation events in the ANS geographical core took place at 1.1-1.2 Ga and were followed by crustal differentiation starting at *0.9 Ga.