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Three post-orogenic granitic plutons exposed in the Egyptian basement complex, namely Homr Akarem, Homrit Mukbid and Nuweibi were selected for geochemical and Nd-Sr isotopic studies. Based on petrographic and geochemical considerations, the granitic rocks are divided into medium grained pink granites and albite-rich granites. Both types exhibit peraluminous character with many chemical similarities to the high Y/Nb A-subtype granites. Owing to the extreme fractionated nature and complex magma source of these granitic rocks in addition to the high volatile activity, their compositions resemble within-plate magma originated in attenuated crustal lithosphere.

Whole-rock Rb-Sr isochron ages of the medium-grained pink granites from Homr Akarem and Homrit Mukbid plutons are 541 +/- 4 Ma and 527 +/- 26 Ma, respectively. The Nuweibi albite granite (NAG) represents the youngest granite phase and yields a Rb-Sr age of 490 +/- 27 Ma. The medium-grained pink granites show a moderate and narrow range of initial Sr-87/Sr-86 ratio (0.7064-0.7081) and negative epsilon(Nd)(t) values (-1.31 to -6.68). The NAG has an initial Sr-87/Sr-86 (0.7071) and epsilon(Nd)(t) (-3.26 to -4.72), comparable to those of the medium-grained pink granites. The Sm-Nd data yield model ages (T-DM) of 0.96 to 1.70 Ga. Similar Nd model ages (1.2-1.8 Ga) have been reported for other post-orogenic granites from southwest Egypt and northern Sudan. The Nd and Sr isotopic compositions of the studied mineralized granites suggest the involvement of old, LREE-enriched continental crust of Pre-Pan-African age and lower crust- or mantle-derived magmas. The Nd and Sr isotopic variations can be explained by a mixing hypothesis.