Hydrothermal Alteration and Mineralization of the Gujareti Ore Occurrence (Achara–Trialeti Fold-and-Thrust Belt, Georgia)

Abstract

Hydrothermal alteration plays a fundamental role in understanding ore-forming processes and improving mineral exploration. This study presents an integrated characterization of the Gujareti hydrothermal system (Achara–Trialeti Fold-and-Thrust Belt, Georgia) using ASTER remote sensing, petrographic and ore microscopic observations, X-ray diffraction (XRD), and whole-rock X-ray fluorescence (XRF) geochemistry. Satellite-derived alteration mapping identified three principal alteration domains, including silica-enriched, mica-rich, and carbonatized zones, which exhibit a close spatial association with structurally controlled mineralization. Petrographic and XRD analyses indicate that the alteration assemblage is dominated by quartz and sericite with localized alunite and calcite, whereas ore microscopy reveals pyrite as the principal sulfide, accompanied by chalcopyrite, sphalerite, minor galena, and microscopic native gold. Geochemical discrimination diagrams consistently indicate extensive silicification, alkali depletion, and progressive feldspar alteration, reflecting a well-developed hydrothermal alteration system. The strong agreement between remote sensing, mineralogical, and geochemical datasets demonstrates that integrating multiple analytical techniques substantially improves the recognition of alteration patterns and their relationship to mineralization. The proposed multidisciplinary workflow provides a reliable approach for reconstructing hydrothermal evolution and represents an effective exploration strategy applicable to volcanic-hosted hydrothermal systems in the Lesser Caucasus and comparable metallogenic provinces.