Petrogenesis of cogenetic silica-oversaturated and -undersaturated syenites of Abu Khruq ring complex, South Eastern Desert, Egypt GEOCHEMISTRY AND PETROGENESIS OF THE CALC-ALKALINE GRANITOIDS FROM THE NORTHERN ARABIAN–NUBIAN SHIELD. A CASE STUDY FROM WADI EL-AKHDER GRANITOIDS, SOUTHERN SINAI, EGYPT Genesis and Tectonic Implications of Kabr El-Bonaya Ultramafic Rocks, Sinai Peninsula, Egypt: Constraints from Mineralogical and Geochemical Characteristics Geotectonic significance of the Neoproterozoic ophiolitic metagabbros of Muiswirab area, South Eastern Desert, Egypt: constraints from their mineralogical and geochemical characteristics Petrogenesis of Zeiatit gabbroic rocks in the Southern Eastern Desert of Egypt: Discrimination of arc-related Neoproterozoic gabbros