Document Type : Original Article
Authors
1
Prof. of Petrology, Geology Department, Faculty of Science, Tanta University, Egypt
2
Prof. of Petrology, Geology Department, Faculty of Science, Tanta University, Egypt.
3
Demonstrator, Geology Department, Faculty of Science, Tanta University, Egypt
4
Geological Sciences Department, National Research Centre, 12622-Dokki, Cairo, Egypt
5
Faculty of Science, Tanta University, Egypt.
Abstract
Wadi El-Nabi' area (῀400km2) constitutes Precambrian intrusive-extrusive complex related to the Egyptian-Nubian Shield (ENS). It includes ophiolitic serpentinites, felsic-mafic metavolcanics (bimodal metavolcanics), metapyroclastics (metatuffs), metagabbro-diorite complex, olivine gabbros, and troctolites (young gabbros), and monzo-syenogranites (younger granites). The field and lab radiometric measurements of radioelements, and their geochemical characteristics were carried out for (15) samples of monzo-syenogranites (55 km2) by RS-230 γ-ray spectroscopy, and HpGe detector. Chemical analyses by ICP-MS are also obtained for the studied granitic rocks to verify the concentrations of specific elements and their inter-relationships with (238U (ppm), 232Th (ppm), and 40K (%). Regarding the RS-230 measurements, the of radionuclide concentrations range are (4- 6.6 ppm) for eU, (8.7-14.75 ppm) for eTh, and (3.62- 5.15%) for K%. On the other hand, the chemical analysis for 238U, 232Th (ppm), and 40K%, of monzo-syenogranites give rise to 3.04 ppm for 238U, 9.44 ppm for 232Th, and 1.82 % for 40K%. The field, and lab radiometric measurements, chemical parameters of P, and D-factors (226Ra/238U, and Uc/Ur respectively) give rise to the disequilibrium state is well evident. On the other hand, the chemical interpretations given by multi-variation diagrams among 238U, 232Th, and 40K, as well as selected elements indicate that the origin of the studied radioactive elements are related to the magmatic process, followed by the later post-magmatic process (hydrothermal).
Keywords
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