Late Neoproterozoic basement rocks of Kadabora-Suwayqat area, Central Eastern Desert, Egypt: geochemical and remote sensing characterization

Abstract

Kadabora-Suwayqat area, in the Central Eastern Desert of Egypt, is built up by a wide variety of non-consanguineous, basement rock units, which represent a tectono-stratigraphic suite within the frame of the Late Neoproterozoic, Pan-African Arabian-Nubian Shield. They were developed from different magma sources at varied tectonic settings through subsequent tectono-magmatic processes. They cover a wide compositional range of the Pan-African legend in the Eastern Desert of Egypt comprising ophiolitic, island-arc, and within-plate assemblages. The ophiolitic serpentinites were obducted onto arc-related metavolcanics and intruded by gabbroic and syn-late to post tectonic granitoids. Geochemically, the precursor of the ophiolitic serpentinites seems to be peridotite (harzburgite). The basic, intermediate, and acidic metavolcanics imply a transitional stage between an island-arc and a proper active continental margin setting. They exhibit with the gabbroic rocks a diagnostic subduction-related island-arc, calc-alkaline affinity. The granitoids comprise both arc-related, calc-alkaline I-type and within-plate, anorogenic A-type varieties. These rocks have been successfully discriminated on Landsat 8 images including Minimum Noise Fraction (MNF; 4, 3, 7), Principal Component Analysis (PCA; PC6, PC2, PC7), and various band ratios (b6/b2, b6/b7, b6/b5×b4b5) and (b7/b6, b7/b5, b5/b3). ASTER clay index (5×7/6) and silica index (10/13) discriminated the granitoid rocks, while the serpentinite-talc carbonate and metavolcanic rocks are distinguished on the ASTER images of amphibole index (6+9/7+8) and (6/8).