Characterization of lead and zinc in catchment sediments and their relationship with lead‑zinc mineralization from the Sino–Mongolian border region

The Sino–Mongolian border region is one of the most important metallogenic belts in Central Asia and is an important source of Au, Ag, Pb, Zn, Sn, Cu, and rare metals in southern Mongolia and northern China. The variations in Pb and Zn concentrations and their spatial distribution in the region can indirectly reflect the distribution pattern of mineral resources in the region and provide reference data for the exploration of elements associated with Pb and Zn (e.g., Au, Ag, Cu, and Mn). Moreover, Pb and Zn data are valuable in environmental research because the elements are persistent and potentially toxic heavy metals. Although numerous geological and geochemical surveys of PbZn resources have been conducted in China, the Sino–Mongolian border region remains under studied. Therefore, in this study, we performed an integrated and comprehensive analytical study of single-element and combined PbZn geochemical anomalies. A total of 10,452 catchment sediment samples were collected. Pb concentrations in the samples ranged from 1.90 to 494 mg/kg, while Zn concentrations ranged from 3.00 to 1940 mg/kg. Of these, the median and mean values for Pb were 19.4 mg/kg and 55.0 mg/kg, respectively, while the median and mean values for Zn were 19.9 mg/kg and 58.0 mg/kg, respectively. To characterize the concentration and spatial distribution of Pb and Zn in the study area, we conducted an exhaustive study across several dimensions, considering the geological setting, mineral development, and utilization, and explored the key factors affecting these characteristics. A total of 53 Pb, Zn geochemical anomalies (geochemical province/domain, Pb > 23.1 mg/kg and Zn > 75 mg/kg, > Q85%), including 17 PbZn combined geochemical anomalies, were identified in this study. The PbZn combined geochemical anomalies were mainly concentrated in the Altai region in the west and the Daxinganling region in the east of the study area and are closely related to the distribution of known PbZn deposits. The high-quality geochemical data produced during this study could be an important reference for future mineral exploration work and environmental change studies in the Sino–Mongolian border region.