A suite of volcanic and plutonic rocks represent the products of Pan-African orogeny; constitute the major litho-tectonic association of Gabal Abu-Mesaid area located in the northern part of the Eastern Desert. These litho-tectonic units are the syn-tectonic older granitoids, mature arc to continental arc Dokhan Volcanics and the associated pyroclastics as well as the widely distributed Post- to late-tectonic younger granites. Almost rock units are invaded by different types of dyke swarms.
The older granitoids are mainly represented by granodiorites that are tectonically described as syn-tectonic plutonites. Geochemically, these rocks are metaluminous, typically l-type that restricted to the pre-late collision stage evolved in a volcanic arc and formed under compressional regime at the lower level of the earth's crust.
Dokhan volcanics demonstrate a wide spectrum of varieties in which andesites associated with rhyolites and andesitic tuffs, agglomerates as well as ignimbrite are well notified. They are typical calc-alkaline rock series formed in Andean type subduction-related volcanic arc suites. That restricted to the pre-collision stage evolved in a volcanic arc and formed under compressional regime at the lower and middle level of the earth's crust
Younger granites can be differentiated into two types namely: the fine-grained biotite granites and the medium-to coarse- grained hornblende biotite granites, where these rocks display within plate magmatism, peraluminous calc- alkaline to mild alkaline trend to be potassic affinities.