Geochemical insights, physico-mechanical properties and lithological enhancement using PRISMA hyperspectral data of intrusive rocks at Gabal Nikeiba area, South Eastern Desert, Egypt

Abstract

This study presents an integrated study of remote sensing, fieldwork, petrographic, geochemical analyses and geotechnical properties of intrusive rocks in the Nikeiba area, South-Eastern Desert, Egypt. Gabal Nikeiba area is composed of Neoproterozoic rocks, including island-arc assemblages (mafic metavolcanics and metagabbro-diorite) and syn- (granodiorite and tonalite) to post-tectonic granitoids (syenogranite, alkali feldspar granite and quartz syenite), followed by post-granitic dikes of various compositions. PRISMA (PRecursore IperSpettrale della Missione Applicativa) hyperspectral data effectively delineated lithological units and structural features. The lithological discrimination serves as a spatial blueprint, ensuring that field sampling for geochemical analysis is optimized and geomechanical characterization is strategically targeted. The old magmatic phase is represented by a calc-alkaline series, typical of magmas formed in a subduction or continental collision setting. The post-collisional granites are subdivided into two magmatic phases, an older one including syenogranite and alkali feldspar granite, and a younger event includes quartz syenite. They have chemical signatures typical for A-type granites (i.e., high SiO ₂ , K ₂ O, Fe/Mg ratio, low CaO, MgO) which are associated with extensional tectonics, crustal melting and intraplate environments. Rare earth element (REE) patterns show light REE (LREE) enrichment and a distinct slope from LREEs to heavy REEs (HREEs). Bulk densities range from 2.48 to 2.7 g/cm ³ , with low porosity and water absorption, except for granodiorite. Quartz syenite and alkali feldspar granite exhibit superior physical properties and meet American Society for Testing and Materials (ASTM) C615 standards. Quartz syenite shows the highest mechanical strength and lowest abrasion, making it highly durable. Overall, quartz syenite is the most suitable candidate for dimensional stone applications.