Multi-Data Integration for Delineating Listweanization Alteration Zones and Associated Gold Mineralization in the Um-Khasila Area, Central Eastern Desert, Egypt

Abstract Listweanization of ultramafic rocks commonly results in diagnostic alteration mineral assemblages that serve as key indicators of potentially economic mineralization. This study employed ASTER and Landsat 7 ETM+ multispectral data to delineate listweanization alteration zones. Most alteration mineral spectra were extracted using selective Principal Component Analysis (PCA), while the ASTER thermal infrared band ratio (14:12) facilitated silica isolation. ASTER successfully identified argillic, phyllic, and propylitic alteration alongside carbonates and silica, whereas Landsat 7 identified undifferentiated clays and iron oxides. Remote sensing results were subsequently validated through fieldwork and confirmed by petrographic investigations and X-ray diffraction (XRD) analysis, which proved to be an essential approach to facilitate mineral exploration. Furthermore, a fire assay was carried out on rock chip samples, followed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) for Au quantification and confirmation of potential gold mineralization. This revealed that higher Au concentrations (up to 944 ppb) are spatially and genetically associated with highly altered carbonate-silica-iron oxide alteration zones coinciding with talc carbonate and listweanite. In contrast, fresh ultramafic and least-altered serpentinite protoliths have depleted gold concentrations (1-5 ppb). The integrated multispectral satellite datasets (ASTER and Landsat 7 ETM+) with fieldwork, petrography, and laboratory analyses (XRD and ICP-AES) improved the precision of delineating key alteration mineral zones associated with listweanization. This joint workflow provides a reliable framework to rapidly prioritize gold exploration targets in the study area and analogous ophiolite-granite-greenstone terranes globally.