Integrated hyperspectral-multispectral mapping of shear-associated hydrothermal alteration and gold mineralization validated by geochemical and isotopic data, southern Arabian Shield

Shear-zone-hosted gold systems are widespread in the southern Arabian Shield, yet the geometric and genetic links between deformation architecture, hydrothermal alteration, and ore-forming fluids remain insufficiently constrained at the scale of individual structural corridors. This study integrates PRISMA, ASTER, and Sentinel-2 remote sensing data with structural analysis, petrography, whole-rock geochemistry, fire assay, and C–O stable isotope data to develop a deformation-controlled mineralization model for the Wadi Al Awja district, Asir terrane. Selective PCA and MNF transformations of PRISMA data delineate narrow and laterally continuous carbonate–silicification alteration belts aligned with N–S to NNE–SSW high-strain zones, providing markedly improved resolution over multispectral datasets. The mapped alteration belts spatially coincide with fold-closure domains and a central shear corridor defined by dense foliation trajectories and reactivated ductile–brittle structures. Fire assay data demonstrate that gold enrichment (locally reaching several ppm Au) is confined to ductilely deformed quartz–carbonate and carbonate–silicified zones within these high-strain domains, whereas weakly altered and late stage brittle silicified rocks are consistently barren. Petrographic observations of ribbon quartz, boudinaged quartz–carbonate veins, and mylonitic fabrics corroborate syn-deformational fluid flow and structurally focused permeability enhancement, emphasizing the primacy of progressive deformation in localizing mineralization. Carbonate δ 13 C values (− 6.7‰ to + 4.2‰ VPDB) are compatible with CO 2 -rich fluids of dominantly metamorphic affinity at estimated temperatures of ~ 250–300 °C, consistent with the quartz–carbonate–chlorite ± sulfide assemblage. The wide δ 18 O range (− 18.6‰ to + 2.1‰ VPDB) records variable fluid–rock interaction and progressive isotopic re-equilibration during episodic fluid infiltration along long-lived Neoproterozoic shear zones. The integrated structural, spectral, geochemical, and isotopic constraints support an epigenetic, shear-zone-hosted gold model in which brittle–ductile reactivation generated transient permeability, focused CO 2 -rich fluids, and incremental gold deposition. The integrated structural, spectral, geochemical, and isotopic constraints support an epigenetic, shear-zone-hosted gold model in which brittle–ductile reactivation generated transient permeability, focused CO 2 -rich fluids, and incremental gold deposition. The results demonstrate that carbonate–silicification alteration is a reliable exploration proxy particularly when confined to high-strain structural corridors.