Remote Sensing-Based Lithological Mapping of the Qena-Safaga Shear Zone Juxtaposing Northern and Central Tectonic Provinces of The Egyptian Nubian Shield

Abstract

Integration of remote sensing data (Landsat- 8, ASTER and Sentinel 2A) with field and petrographic studies is utilized to update the lithological/geological mapping of the central Qena-Safaga Shear Zone that juxtaposes the Northern Extensional Province against the Central Transpressional Province of the Egyptian Nubian Shield. The Neoproterozoic basement succession in the study area is classified into ophiolitic mélange, syn- tectonic granitoids, late- tectonic granitoids, Dokhan Volcanics and post- tectonic granitoids. These rock suits are dissected by NE-SW oriented dikes and NE-SW and NW-SE trending strike-slip faults. A number of remote sensing techniques (e.g., False Color Composites; FCC, Band Ratios; BR, Principal Component Analysis; PCA and Image Classification) were applied in the verification of the exposed litho-units. The FCC (RGB 7 5 3 for Landsat- 8 and 10 11 6 for Sentinel 2A), PCA (RGB 1 2 3, 3 2 1 and 6 4 3 for Landsat- 8; RGB 6 5 7 for Sentinel 2 A; and RGB 1 2 4 for ASTER), BR (RGB 4/3, 6/7, 6/5 for Landsat-8; and RGB 1/3, (5/3/+ ½), 5/7 for ASTER) and Supervised Classification including parallepiped method and Maximum Likelihood for Sentinel 2A are effective remote sensing techniques in rock discrimination. Besides, some alteration zones were recognized including phyllic (muscovite, b7/b6 for ASTER), ferrous silicates (chlorite, b5/b6 for Landsat-8), carbonate (calcite, b6/b7 for Landsat-8), kaolinite (b7/b5 for ASTER) and hydroxyl group (alunite, b4/b5 for ASTER). Such alterations exhibit bright pixels depending on the DN band threshold (DN band threshold= mean + 2* standard deviation).