Ahmed Abd El-Dayiem Abd El-Fatah; Ahmed Ali Madani; Adel Abd Allah Surour; Mokles Kamal Azer
Abstract
The present work aims to enhance the utilization of Landsat-8 data in geological mapping when they are paired with spectroscopic measurements and field observations. This is applied to map and differentiate the different plutonic rocks in the Gebel El-Bakriyah pluton, a peculiar igneous body in the central ...
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The present work aims to enhance the utilization of Landsat-8 data in geological mapping when they are paired with spectroscopic measurements and field observations. This is applied to map and differentiate the different plutonic rocks in the Gebel El-Bakriyah pluton, a peculiar igneous body in the central Eastern Desert of Egypt. Therefore, we use a combination of remote sensing techniques such as principal component analysis (PCA), band ratios, fusion technique, and spectroscopic measurements to interpret igneous lithologies, and produce a new geologic map of the Gebel El-Bakriyah area. A false-color composite principal component image PC1, PC2, and PC3 in red, green, and blue (RGB) discriminates between alkali feldspar granite, syenogranite, and younger gabbro. In general, the spectral profiles of granites exhibit three distinct absorption features in the 1.4, 1.9, and 2.2 μm wavelength regions. These features are attributed mainly to altered mineral products such as kaolinite, sericite, and chlorite. The spectral profiles of pink and alkali feldspar granites show a broad absorption feature at 0.9 μm, which is attributed to a considerable Fe content. The spectral profiles of fresh, younger gabbros exhibit absorption features around 1 μm and 2.2 μm. A false-color composite image provides the most accurate discrimination of the three varieties of younger granites with band ratios of 7/4, 6/3, and 3/1 in RGB. The data that appear in the present work strengthen the usefulness of Landsat-8 imagery and spectroscopic measurements as a prevailing grouping to discriminate and map Neoproterozoic shield rocks in the Eastern Desert of Egypt.
Deemah Saad Mahmoud; Ahmed Ali Madani; Said Mohamed Said; Mohamed Mokhtar Yehia; Tamer Nassar
Abstract
The eastern border of the Nile valley south of Cairo is distinguished by numerous springs and associated surface water bodies, e.g. Ain El-Sira, Helwan, and Atfih. Except the latter, all of them were disseminated in urban areas, and were hardly detected by remote sensing data. Thus, studying the surface ...
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The eastern border of the Nile valley south of Cairo is distinguished by numerous springs and associated surface water bodies, e.g. Ain El-Sira, Helwan, and Atfih. Except the latter, all of them were disseminated in urban areas, and were hardly detected by remote sensing data. Thus, studying the surface water of Atfih spring is key to understanding the nature of the east Nile spring system. Change in this surface water has been detected based on the integration between the spatiotemporal analysis of the multi-spectral satellite images and the Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) rainfall data from 1987 to 2019, and the field investigation. The normalized differential water index analysis reveals an increase in the surface area of the Atfih water body by two to three times during the years 2016-2017. The results clarified the relationship between the appearance of the surface water of Atfih spring and rainfall amounts. Another factor controlling the Atfih water body treated in this work is the geological structures. A field survey aided by the processed satellite data revealed the presence of three fault populations: WNW-ESE, E-W to ENE-WSW, and NNE-SSW. The E-W to ENE-oriented faults are the main faults and have a right-lateral strike-slip sense of movement. This fault pattern and Pliocene shale have a substantial impact on the appearance of the Atfih water body. These faults act as a horizontal channel that allows lateral movement of meteoric water through Eocene carbonate, and water recharge occurs at the highly fractured strike-slip transfer zones.
