Geological mapping of Neoproterozoic rocks in Zug El-Bohar area, NW Red Sea rift system, Egypt: an integrated hyperspectral remote sensing, petrographic, and geochemical approach

Abstract

Zug El-Bohar area, situated in the Central Eastern Desert of Egypt, has garnered increasing attention due to its polymetallic potential, particularly the notable enrichment in radioactive elements, including uranium (U) and thorium (Th), along with base metals including lead (Pb), zinc (Zn), and arsenic (As), in addition to alkaline-earth elements like strontium (Sr). This mineralogical diversity underscores the need for an integrated and systematic exploration approach. For the first time in this region, high-resolution Sentinel-2 and PRISMA hyperspectral datasets were synergistically employed to conduct detailed lithological and alteration mapping. A suite of advanced image processing methods, including principal component analysis (PCA), false-color composites (FCCs), Minimum Noise Fraction (MNF), Sequential Maximum Angle Convex Cone (SMACC), and band ratio, has been utilized to enhance spectral discrimination and delineate previously unrecognized lithological domains and hydrothermal alteration signatures. The resulting remote sensing outputs revealed the complex lithological architecture of the area, comprising metasediment successions and metavolcanic rocks intruded by multiple granitoid bodies. Field validation was achieved through extensive field investigations, petrographic examinations, and whole-rock geochemical analyses. Petrographic and geochemical studies indicate that the metasedimentary rocks are divided into metagreywackes and slates, distinguished by schistosity and chloritization. Metavolcanic rocks vary from metabasaltic andesite to metarhyolites, exhibiting significant alteration and an increase in opaque and accessory minerals. Older granites with limited occurrences consist of coarse-grained granodiorite that has undergone tectonic deformation, comprising plagioclase, quartz, and biotite, with considerable alteration to chlorite and sericite, which were documented for the first time at the Zug El-Bohar area. Younger granites include alkali-feldspar granite and syenogranite, which are rich in quartz, K-feldspar, and biotite, exhibit perthitic textures, and contain abundant accessory minerals. The alkali-feldspar granite and syenogranite fill in the A-type granite, exhibiting calc-alkaline characteristics and intraplate signatures compatible with Egyptian younger granitoids, whereas the granodiorite demonstrates calc-alkaline I-type properties compared to Egyptian older granitoids. The close agreement between remote sensing interpretations and in situ geological data underscores the efficacy of the applied multi-method approach in accurately mapping complex terrains and identifying mineralization zones. A graphical abstract of our study. • The synergistic integration of Sentinel-2 multispectral and PRISMA hyperspectral datasets, coupled with a suite of advanced image-processing algorithms, has significantly enhanced the spectral discrimination and lithological interpretation of the Zug El-Bohar region. • The Sentinel-2 satellite imagery has demonstrated exceptional proficiency not only in lithological differentiation but also in resolving the intricate structural framework of the Zug El-Bohar area. A diverse array of tectonic features, including intrusive dyke swarms, fault networks, fold systems, and pervasive foliations, has been distinctly delineated. • Despite the partial concealment of the basement rocks beneath Phanerozoic cover sequences, the integration of advanced remote sensing analyses with comprehensive field investigations has enabled the successful identification of critical surface expressions of mineralized zones and the precise delineation of hydrothermal alteration patterns ( hydroxyl-bearing assemblages, and zones enriched in ferrous iron oxides) within the Zug El-Bohar area. • The outcomes derived from remote sensing interpretations were rigorously validated through systematic ground-truthing efforts, encompassing extensive field investigations, detailed petrographic examinations, and comprehensive whole-rock geochemical analyses. • The spectral signatures extracted from hyperspectral imagery display remarkable concordance with ground-truth observations, thereby attesting to the analytical robustness and diagnostic fidelity of the applied remote sensing methodologies in resolving geologically complex and compositionally heterogeneous terrains.