Mineralogy, Radioactivity and Ree-Geochemistry of Batoga Monzogranite and Associated Pegmatite, Southeastern Desert, Egypt

Abstract

The studied area lies in the southern part of the Eastern Desert of Egypt to the southwest of Ras Benas. This area is covered by metagabbros, tonalite and monzogranite. The pegmatites occur as elongated, small pockets and lenses in the monzogranite and display sharp contacts with the host granite. In all cases, the pegmatites are characterized by obvious simple zonation.The radiometric studies of monzogranite and associated pegmatite samples show that these rocks are uraniferous, where their average equivalent uranium contents are 12 ppm and 134 ppm, respectively. The uraniferous character was confirmed by the average eTh/eU ratios (1.13 and 0.96, respectively). The average ratios of P factor of the studied granites and associated pegmatites are more than one (1.89 and 16.35, respectively), indicating disequilibrium in U-decay series due to addition of uranium to these rocks. The present study proved that the presence of uranothorite, uranophane and the uranium-bearing minerals such as zircon, monazite, allanite and fluorite are responsible for both U and Th contents in the studied granite and associated pegmatite.The normalized REE pattern of the monzogranite and associated pegmatite have similar geochemical characteristics. Where the REE patterns show a LREE relatively enriched feature with strong negative Eu-anomaly. The characteristic high LREE relative to HREE of the analyzed samples is attributed to the presence of the allanite, monazite and apatite minerals. The slightly positive Tb anomaly in the studied granites attributed to its preferential accommodation within the fluorite structure.with the hydrothermal alteration (petrography, radioactivity, mineralogy and rare earth geochemistry of the granitic rocks of Gabal Batoga in order to discuss the genesis of the radioactive anomalies. FIELD AND PETROGRAPHIC OBSERVATIONThe study area is covered by metagabbros, tonalite and younger granites.The Tonalite show lows resistance to weathering. They are characterized by cavernous, exfoliation and bouldary weathering and monumental like -shape. Also in places, some irregular shaped enclosed of microgranular mafic rocks enclosed in these rocks.Monzogranite is marked by relatively higher mountain, with prominent peak up to 801 m above sea level. The rocks are equigranular, medium-grained with pale buff to white colors, and have rounded pluton and show intrusive contacts to the older rocks. Generally, the monzogranite intrudes the older rocks by sending offshoots invading them. Sometimes,