Analysis of metal–element association halos within fault zones for the exploration of concealed ore-bodies — A case study of the Qilinchang Zn–Pb–(Ag–Ge) deposit in the Huize mine district, northeastern Yunnan, China

• MEAHFZ (Metal-element association halos in fault zones) ore-finding method is effective for deep ore exploration.
• Anomaly shifting direction indicates pitching direction of concealed ore-bodies.
• Anomaly gradient diminishes to show the dipping direction of ore bodies.
• The Huize deposit has upgraded to super-largest and richest Zn–Pb deposits over the world.

Metal–element association halos within mineralization-related fault zones (MEAHFZ) and their geochemical characteristics are examined as prospective targets to explore for concealed ore-bodies at the Qilinchang deposit, Huize Zn–Pb–(Ag–Ge) district, located in the Sichuan–Yunnan–Guizhou Triangular area of poly-metallic Zn–Pb deposits in southwestern China. By detailed study of the geochemical anomalies, concealed ore-bodies have been successfully found within the MEAHFZ, leading to a 2 million ton (Mt) increase in the Zn–Pb metal reserves. The successful exploration in the Huize district demonstrates that the MEAHFZ prospecting method has the potential to increase metal reserves in the brown field and to find new deposits in green field or new ore-bodies surrounding areas of the mine area. Variations of gradient value for primary anomalies, controlled by structures, may predict the dipping direction and the extension of the concealed ore-bodies. Also, the shifting direction of anomalies at different levels reflects the dip direction of concealed ore-bodies at depth. Thus, this method can not only find concealed ore-bodies, but also provide important information about deposit genesis. The method is low cost and its operation is simple, and can be used in exploration for concealed ore-bodies at depth in areas such as the Zn–Pb deposits in Northeastern Yunnan, the Sichuan–Yunnan–Guizhou Triangular area of poly-metallic Zn–Pb mineralization and the other similar areas over the world where the ores are obviously controlled by structures.