APPLICATION OF REMOTE SENSING AND AIRBORNE SPECTROMETRIC DATA ANALYSIS TO DELINEATE THE ALTERATION ZONES AT GABAL SUWAYQAT AREA CENTRAL EASTERN DESERT, EGYPT

Abstract

The present study aims to study the potentiality of promised radioactive zones in the granitic rocks at Gable Suwayqat area. The Processed Landsat ETM+ data false color composite image (FCC) band 7, 4, 2 in RGB, band ratios (5/7, 4/3, 3/1), (5/7, 5/1, 4), (3/1, 5/4,7/5) in red green blue and 5/7 in gray color. Principal component analysis (Pc2, Pc3, Pc5) in RGB were prepared for discriminating rock unites. Verified by the fieldwork and airborne gammaray spectrometric surveyed data enabled to differentiate the acidic and mafic rocks, and identified the alteration zones in the granitic rocks, which were effectively distinguished into high felsic and low ferromagnesian mineral contents, relative to the other granite areas. The gamma-ray spectrometric interpretations reveal that most of radiometric anomalies recorded at north eastern and south western sides of study area. The structural framework and consequent surface features controled and managed the distribution and localization of the radioactive elements and the environmental dose rates in the area. The high fractures density act as good channels and passages for the mineral bearing hydrothermal ascending fluids and the percolating meteoric water that leached uranium mineralization and redeposited it in the adjacent fractured sites. Such processes in the granitic masses may be responsible for the presence of uranium and thorium mineralizations in these granites. The calculated dose rates range between 0.1 and 1.1m Sv/year, indicating that the study area remains safe and under the maximum permissible safe radiation dose rate without harm to the individual, with continuous external irradiation of the whole body. The results show that the target area has some eU, eTh, and K% anomalies related to the biotite granites and are structurally controlled by the dominated faults.