Integration of Remotely Sensed Data and the Petrographic Analysis for Lithological Mapping of Neoproterozoic Basement Rocks at Um Had Area, Central Eastern Desert, Egypt

This study aims to map the rock types in the Um Had region by integrating remote sensing applications of Landsat-8 (OLI) image processing, field studies, and petrographic investigations. The present work involves updating the existing geological map of the Um Had area in the central Eastern Desert, Egypt, due to the lack of a precise and accurate geological map. Several rock types dating to the Neoproterozoic Era, including oceanic crust (ophiolitic and island arc) and continental crust assemblages, originated in the region during two tectonic stages (late to post-orogenic and syn-orogenic). Remote sensing technology is already widely utilized for various geological domains like mineralogy, lithology mapping, geomorphology, and others. In our study, it is specifically used for lithological mapping. We utilized the optimum index factor and correlation coefficient methods to identify the most effective results from False-Color Composite (FCC), Principal Component Analysis (PC), and Band Ratio (BR). These techniques, combined with supervised classification, enabled us to distinguish among different rock units based on their spectral signatures. All results were combined with the previously mentioned techniques that include principal component images (PC1, PC4, and PC3; PC2, PC3, and PC4) and band ratio images (2/4, 5/7, and 5/3 × 2; 4/2, 5/6, and 6/7). Consequently, this supported the geological mapping and confirmed the field and petrographic investigations. This approach enabled the identification of seventeen distinct rock units, namely serpentinite, biotite schist, talc schist, metabasalt, metaandesite, metadacite, metarhyolite, metagabbro, quartz diorite, tonalite, rhyolite, granodiorite, monzogranite, syenogranite, siltstone, graywacke, and conglomerate. A comparative analysis of the newly modified and created lithological maps with previously published maps of the Um Had region significantly enhanced the accuracy and robustness of geological mapping and rock unit identification.