Structural geochemical anomalies and prospecting prediction of the Qingshan Pb–Zn Deposit in Northwestern Guizhou Province, China

Abstract

The Qingshan Pb–Zn deposit is characterized by high-grade ores (averaging 7.72% Pb and 32.6% Zn) and significant structurally controlled mineralization, both of which are of substantial economic and genetic importance. Although previous studies have elucidated the sources of ore-forming materials and their structural controls, tectono-geochemical research has been predominantly confined to shallow subsurface workings, with analyses limited to two-dimensional anomalies at the individual level. Consequently, both the three-dimensional (3D) distribution and vertical zoning of these anomalies remain poorly understood, and a comprehensive spatial correlation framework is yet to be established. This gap impedes in-depth exploration planning. To address this issue, systematic tectono-geochemical sampling and analysis were conducted at three representative levels (1678, 1650, and 1608 m) within the mining area. The R-mode cluster and factor analyses identified three elemental associations: F1 (Ge, Hg, Pb, Zn, Cd, As, Sb, Cu, Ga, In, and W), representing a medium- to low-temperature ore-forming assemblage; F2 (Ni, V, Co, and Mo), corresponding to high-temperature elements; and F3 (Ba and Bi), reflecting a wall-rock alteration assemblage. The 3D anomaly superposition analysis indicates that: (1) the concealed orebody strikes NW and dips steeply SW, with a pronounced SE plunge; (2) ore-transporting structures (F1, F2) and ore-hosting structures (interlayer fault zones) collectively control mineralization; (3) the ore-controlling structures exhibit a step-like distribution; (4) the ore-forming fluids migrate vertically from deep to shallow levels and horizontally from SE to NW. Vertical zoning, determined by the concentration index method, shows a top-to-bottom sequence of Cu-As-Ba-Bi-W → Cd-Ge-Hg-Pb–Zn-Sb → In-Ga-Mo-Ni-V-Co, indicating a typical “inverted zoning” pattern. This inverted zoning pattern indicates multi-stage superposition of mineralization and suggests a significant downward extension of the orebodies and/or the presence of concealed orebodies at depth. Based on these findings, three prospective target areas are proposed, providing a scientific basis for deep exploration in Qingshan and guidance for similar deposits.