Geological, petrological and geochemical studies indicated that there are two distinct types of granitoid rocks: older quartz diorites to granodiorite assemblage and younger granitoids, the latter occurring in two phases. The older granitoids have a meta-aluminous chemistry and a calc-alkaline character, with high MgO, Fe 2 O 3 , TiO 2 , CaO, P 2 O 5 , Sr and low SiO 2 , K 2 O, and Rb. Their major and trace elements data, together with low 87 Sr/ 86 Sr ratios (0.7029±0.0008) are indicative of I-type affinities. The second-and third-phase granitoids range from calc-alkaline to alkaline, respectively. The second-phase granitoids have a peraluminous chemistry and high relative to the third-phase granitoids. The corundum normative nature and field observations suggested that it was formed by partial melting of the lower crust. The third-phase granitoids are alkaline in nature and characterized by higher SiO 2 , Rb, Y, Nb and lower MgO, Sr and Ba values than the younger granitoids (phase II). They are A-type granitoids which were generated from below or within the existing continental crust.

Fluid inclusions in the leucosomes of Wadi Feiran migmatites showed that CO 2 , H 2 O and (H 2 O-CO 2 ) fluids were likely to have been present when partial melting began in these rocks. Low salinity, aqueous fluid, to a lesser extent, CO 2 -rich fluids are the most abundant fluids. The present study suggests that high-density CO 2 inclusions were formed at the earliest stage, while H 2 O inclusions were formed at the late stage. In an intermediate stage, low-density CO 2 and H 2 O, CO 2 inclusions were formed. At the early stage of uplift and during melt crystallization, the CO 2 -bearing vapour was trapped at grain boundaries. At the late stage of uplift, H 2 O released at the time of crystallization of the melt was trapped as inclusions.