Identification of salinity sources in groundwater at Golgohar Mine using self-organizing maps (SOM) and correlation analysis: a hydrogeochemical and isotopic approach, south-central Iran.

Understanding the hydrogeological regime and identifying the sources of salinity in mine pits are crucial for effective groundwater management and mining operations. This study investigates the hydrogeochemistry of the Golgohar Mines in south-central Iran, focusing on Mine Pit No. 2 and the Kheirabad Salt Pan, using a multi-proxy approach that includes Self-Organizing Maps (SOM), Hierarchical Clustering Analysis (HCA), hydrochemical diagrams, and stable isotopic analysis (δH, δO) and tritium. 20 sampling points were selected for hydrogeochemical analyses, 16 sampling points for stable isotopes of δO and δH, and 4 samples for the tritium radioisotope, with sampling conducted during both wet and dry seasons. Based on ionic ratio diagrams, halite dissolution is the predominant process contributing to salinity, with additional influences from reverse cation exchange and gypsum dissolution. The main type and facies of all groundwater samples in the region are Na-Cl and Ca-Cl. The alignment of self-organizing maps with HCA and the hydrochemical classification identified four distinct water clusters: Cluster I is associated with the Kheirabad Salt Pan, Cluster II originates from the hard rock aquifer, Cluster III results from the mixing of multiple sources, including the alluvial aquifer, hard rock aquifer, and brine from the Kheirabad Salt Pan, and Cluster IV is linked to the alluvial aquifer. A hydraulic and hydrogeochemical relationship was observed between the Kheirabad Salt Pan and Mine Pit No. 2, while the main source of salinity in the hard rock aquifer appears to be unrelated to the Kheirabad Salt Pan, potentially involving extensive mixing with other waters. The study highlights the effectiveness of SOM and HCA in elucidating hydrochemical processes in complex mining environments, offering valuable insights for groundwater management.