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The Pan-African granitoids of the Ghorabat area in southern Egypt are composed of two distinct calc-alkaline and alkaline suites. The calc-alkaline suite has a wide compositional range (e.g. silica ranges from 46-77 wt%). The suite is made up of gabbro, diorite, tonalite, granodiorite and porphyritic high-K granite. The suite exhibits geochemical characteristics of are-related magmatism such as enrichment in LILE (Ba & Sr) coupled with depletion in HFSE (Nb, Y & Zr). Major and trace element variations within the suite reflect a dominant role of crystal-liquid fractionation process in its evolution. The early stage of crystallization was controlled by amphibole and plagioclase fractionation, whereas in the late stage, K-feldspar was the major fractionated phase.

The alkaline suite includes metaluminous subsolvus syenogranite and dominant alkali feldspar granite with ubiquitous enclaves. The A-type geochemical affinity of the alkaline granites is manifested by high abundances of some HFSE (Nb and Y) compensated by very low values of LILE (Ba and Sri. The enclaves are chemically alkaline and range in composition from monzonite to granodiorite. The alkaline suite is distinct from the calc-alkaline suite by a higher Fe2O3*/(Fe2O3* + MgO) ranging from 0.85 to 0.97. The enclaves and their hosted alkaline granites do not follow the trend of calc-alkaline suite on AFM diagram, but constitute a distinct different trend parallel to the AF side.

Mineralogical study reveals two distinct trends of mafic mineral associations: i) Mg-rich trend (magnesio-hornblendes and phlogopite) for the calc-alkaline suite and ii) iron-rich trend (edenitic-hastingstic hornblendes and annitic biotites) for the alkaline suite.

The two suites could be derived from melting of amphibolitic lower crust underplated by basaltic magmas with variable water fugacity. Tonalitic melt was generated at an early stage of subduction under high f(H2O). Fractional crystallization of the tonalitic melt produced the lithologic diversity and chemical variation among the calc-alkaline suite. Dehydration melting at the end stage of subduction resulted in mozonitic melt which further evolved to yield the post-orogenic alkaline granites.