Tracing Metal Sources of Geogas with Lead Isotopes: A Case Study on the Bairendaba Silver‐polymetallic Deposit, Inner Mongolia

Abstract Geogas survey is an unconventional geochemical prospecting method that has proven particularly effective in exploring concealed ore deposits. However, its application in covered areas has been questioned due to the lack of a confirmed geogas formation mechanism. Investigating the sources of geogas anomalies can help clarify this mechanism. This study focuses on the Bairendaba silver‐polymetallic deposit, located in a grassland‐covered area. Tracer research was conducted on lead isotope compositions in the mining area by analyzing various solid media (soil, rocks, ores) and geogas samples. The results revealed considerable differences in lead isotope compositions between background geogas samples and solid media. Furthermore, the lead isotope compositions of anomalous geogas samples differed markedly from those of background samples. These anomalous samples are located closer to the ore body, suggesting that ore‐derived lead is incorporated into the geogas. The anomalous lead in geogas is inferred to originate from deep, concealed ore bodies. This study provides a theoretical basis for applying geogas surveys in mineral exploration within covered terrains.