Spectral characterization of the Batuga granite pluton, South Eastern Desert, Egypt: influence of lithological and miner
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ORIGINAL PAPER
Spectral characterization of the Batuga granite pluton, South Eastern Desert, Egypt: influence of lithological and mineralogical variation on ASD Terraspec data Mohamed A. El Sobky 1 & Ahmed A. Madani 3 & Adel A. Surour 2,3 Received: 30 July 2020 / Accepted: 16 November 2020 # Saudi Society for Geosciences 2020
Abstract The paper concerns with potential utilization of Landsat-8 data combined with TerraSpec spectro-radiometer and field studies for mapping and discriminating the different granitic varieties of Batuga pluton in the South Eastern Desert of Egypt. Integrated data of band combination, principal component analysis (PCA), band rationing, fusion technique, and TerraSpec measurements substantially improve visual interpretation to differentiate between granite varieties as well as basalt dikes traversing the pluton. Compilation of field, petrographic, and spectral data enables to distinguish three varieties of granite, namely alkali feldspar granite, garnet-bearing leucogranite, and two-mica granite (monzogranite). False color composite (FCC) image PC1, PC3, and PC4 in R, G, and B, respectively, is successful to discriminate the western part of Batuga pluton as mica granite (monzogranite) but it failed to discriminate the other two granite types. On the other hand, the band ratio combination 6/7, 5/6, and 2/4 successfully used to discriminate the three varieties of granite. Also, the image fusion technique of false color composite (7, 5, & 2) and band ratio (6/7, 5/6, & 2/4) combinations with the high spatial resolution band 2 of Sentinel-2 is applied using the GramSchmidt method. Regarding with TerraSpec measurements, the alkali feldspar granite displays two absorption features around 1.4 and 2.25 μm. Moreover, the garnet-bearing leucogranite shows four little absorption features at 1.4, 2.21, 2.25, and 2.33 μm, while the mica granite shows low reflectance values throughout the VNIR and SWIR regions compared to the other two varieties, and low four absorption features at 1.4, 2.21, 2.25, and 2.33 μm wavelengths. The basalt dikes show a low, nearly flat spectral profile in the VNIR and SWIR wavelength regions and small four absorption features also observed around the 0.65, 1.0, 1.2, and 2.32 μm wavelengths. Data materialized in the paper suggests the usefulness of Landsat-8 and TerraSpec spectroradiometer data as a powerful combination to discriminate the granitic rocks and the traversing basalt dikes as well. Keywords Batuga granite . Lithological discrimination . Mineralogy . ASD Terraspec data . Geological mapping
Introduction Basement rocks in the study area (Wadi Kalalat area, Fig. 1) are exclusively Precambrian and represent a small portion of Responsible Editor: Biswajeet Pradhan * Adel A. Surour [email protected]; [email protected]; [email protected] 1
Egyptian Mineral Resources Authority (EMRA), P.O. Box 11517, Abbasiyah, Cairo, Egypt
2
Petroleum and Mining Geology, Faculty of Advanced Basic Sciences, Galala University, New Galala City, Egypt
3
Department of Geolog
