Mineralogy, Fluid Inclusion, and C-O-Sr Isotope Geochemistry to Unravel the Evolution of the Magmatic-Hydrothermal System at the Igoudrane Silver-Rich Deposit (Imiter District, Eastern Anti-Atlas, Morocco)

The Igoudrane mine with a total production of 700,000 t ore grading 485 g/t Ag is currently one the most productive mines in Imiter district eastern Anti-Atlas Morocco. silver-rich ± base metal deposit occurs dominantly as vein- and hydrothermal breccia-hosted orebodies at interface between lower Ediacaran turbidites Saghro Group unconformably overlying, felsic volcanic, volcaniclastic rocks late Ouarzazate Group. Higher-grade ores are lithologically hosted by uppermost organic-rich black shale unit structurally controlled intersection subvertical NW- NE-trending fault systems. Ore-related alteration includes, order decreasing abundance, carbonatization, silicification, sericitization, chloritization. Three primary paragenetic stages veining associated silver mineralization have been recognized: (1) early pyrite + quartz Ag-bearing sulfides sulfosalts; (2) main sulfosalts calcite fluorite dolomite; (3) base-metal (galena, sphalerite, pyrite, chalcopyrite). Irrespective stage, dominant minerals Ag-Hg amalgam, argentite, freibergite, acanthite, polybasite, pyrargyrite, proustite. Fluid inclusion data show trend temperatures time, from stage (Th = 180 12 °C) to 146 7 °C), consistent fluid mixing, cooling, and/or dilution. coexistence aqueous-rich vapor-rich inclusions together variations bulk salinity (NaCl CaCl2) mineralizing fluids during similar temperatures, indicate that boiling subsequent degassing occurred ore-forming event due pressure decrease. Calculated δ18Ofluid values along REE+Y Sr isotope constraints suggest originated predominantly magmatic source, although incursion meteoric waters collapse system could contributed deposition. post-ore, quartz-carbonate-dominated was deposited dilute Ca-Na-Cl-bearing temperature below 150 °C. Overall, fluid–rock interaction shales major faults thin permeable horizons, boiling-degassing—with dilution—were mechanisms