Geochemical vectors to ore and environmental significance at the Chatree epithermal low-sulfidation deposit, Thailand

Understanding geochemical zoning, including major components, minor components, and trace elements, in ore deposits can significantly improve Au exploration. Therefore, in this study, we focus on the geochemical characteristics of ore and alteration zones in the largest low-sulfidation (LS) epithermal Au–Ag deposit in Thailand, namely Chatree deposit. The occurrence of metal and metalloids can be distinguished into three groups: (1) major components in ore minerals (e.g., As, Cu, Fe, Pb, Sb, and Zn), (2) trace elements in ore minerals (e.g., As, Cd, Hg, and Mn), and (3) trace elements in gangue minerals (e.g., Mn). This study suggests that the ore minerals of a shallow system of the epithermal LS deposit are enriched in As, Sb, and Hg compared to the deeper system. Hydrothermal alteration leads to enrichment of K₂O and depletion of Na₂O and CaO. Besides major oxides, some low-field strength elements (e.g., Rb, and Ba) show the same behavior as K₂O, whereas Sr is similar to CaO. In addition, positive Eu anomalies are associated with hydrothermal alteration. For metals and metalloids, arsenic is an important pathfinder element because its content is associated with the electrum occurrence and significantly increases toward the ore zone. Mn, Pb, and Cd are prominent in the ore zone; whereas, Ti, Al, and Cr decrease toward the ore zone due to dilution from silicification. Furthermore, even though the concentrations of As, Cd, Cr, Pb, and Ni in the ore and alteration zones are lower than Thailand's Total Threshold Limit Concentration (TTLC) for waste, the mine should still implement critical monitoring of these elements.

Graphical abstract