ABSTRACT
In Egypt, a complex of igneous and metamorphic rocks of primarily Precambrian age covers about 100,000 tan in the Eastern Desert and South Sinai, and limited areas in the south Western Desert. Dixon estimated that ultramafic bodies account for 5.3% of all Precambrian outcrops in the Eastern Desert of Egypt. El Ramly & Akaad arranged the basement rock units in a chronological order, and proposed a classification which was adopted by most workers, and in the geologic map of Egypt published by the Geological Survey in 1981. The chemical analyses of igneous rocks from Egypt compiled by Aly et al. show that the older granitoids have a broad compositional spectrum from highly silicic to basic, and typically display a unimodal distribution of SiO2. The lithologic units of the basement complex can be distinguished very generally into two main divisions: the layered sequences and the intrusive rocks.
