الفهرس 
Geological settingOnly 14 pages are availabe for public view
 |  | from | 328 |  |  |
| | | from | 328 | | |
Abstract
The present district constitutes a small part of the Precambrian rocks of Egypt,which cover about 100000 2 km and outcrop over an extensive area in the Eastern Desert. The Precambrian belt is a part of the Arabian- Nubian shield exposed on both sides of the Red Sea, which belong to the ”Pan-African belt”. The cratonization of the Arabian Nubian shield is believed to have taken place during the Pan-African tectonic thermal event which was first named by Kennedy (1964) to describe a continent- 3 wide dominance of K-Ar ages of 5.5+1x 10 m.y. The Egyptian Precambrian belt of the Eastern Desert is composed of Upper Proterozic volcano-sedimentary complex containing scattered mafic-ultramafic bodies (Arabian Desert Supergroup) and intruded by syntectonic to late tectonic granitoid batholiths (Older Granites). This generalized sequence is followed by later calc-alkaline volcanic~ (Dokhan Volcanics) and unconformably overlain by mollase-facies sediments (Hammamat Group). These sediments are cut by post tectonic Pan-African granites (Younger Granites). Analogous units are exposed in a much larger part of western Saudi Arabia, northeastern Sudan and northern Ethiopia. The ages range from 788 (age of crystallization of oceanic crust, Ries and Darbyshire t 1984) to 550 m.y. A major episode of igneous activity occurred at 580 m.y. with the emplacement of numerous (Pan-African) granitic plutons (Fullagar and Greenberg, 1978). A number of plate tectonic models, often contradicatory, have been proposed to explain the evolution of the Arabian-Nubian shield. However, three schools of thought have developed.