Geological Studies on a Recently Discovered Occurrence of Rare Metals Within Shear Zone at Um Samra area, Central Eastern Desert, Egypt

Abstract

Um Samra-Um Bakra area is located at the southern part of the Central Eastern Desert of Egypt. It is delineated by the following co-ordinates; latitudes 25° 15\ and 25° 19\ N and longitudes 34° 05\ and 34° 12\ E. It comprises an area of about 280 square kilometers. Um Samra-Um Bakra area is covered by; 1- metamorphic rocks; a) Ultramafic and related rocks outcrop in the northern and eastern part of the area. b) Arc volcanogenic sediments outcrop in the northern part of the area and intruded by syn-orogenic and post-orogenic granites through intrusive sharp contacts. 2-Igneous rocks; a) syn-orogenic granites crop out at the NW corner of the area. b) Post-orogenic granites vary in composition from monzogranites through syenogranites to alkali feldspar granites with gradational contacts and cut by major WNW-ESE shear zone. 3- Post-granitic dykes (basic and intermediate) and silica veins. Two types of dykes represent the post granite dykes; basic and intermediate dykes. Basic dykes are represented by olivine basaltic dykes and dolerite dykes. Intermediate dykes represented by andesite dykes. Olivine gabbros crop out along the SW and NE border of the area and occur either as roof pendants uplifted by the post-orogenic granites or as xenoliths hosted in the latter rock .They are represented by olivine gabbro and composed mainly of plagioclase, pyroxene and olivine.