Mapping of Gold Prospectivity in the Qingchengzi Pb–Zn–Ag–Au Polymetallic District, China, with Ensemble Learning Algorithms

Ensemble learning (EL) is a machine learning paradigm where multiple learning algorithms (base learners) are trained to solve the same problem. This study provides a comprehensive evaluation of widely used EL algorithms, including bagging, boosting, and stacking, highlighting their significant advantages in terms of accuracy and generalization of mineral prospectivity mapping (MPM). This study tested mapping of prospectivity for gold deposits in the Qingchengzi Pb–Zn–Ag–Au polymetallic district using single machine learning algorithms and EL algorithms. According to the critical and favorable geological factors for magmatic-related medium-temperature hydrothermal lode system for gold deposits, five targeting criteria were extracted from multi-source geoscience datasets (i.e., geological map, gravity and magnetic datasets, stream sediment geochemical datasets) for mineral prospectivity mapping. The receiver operating characteristic curve, the area under the curve, and learning curves were used to evaluate the performance of the tested single and ensemble machine learning algorithms. The results demonstrate that the stacking model, which combines multiple base models for hierarchical feature extraction, achieves the best predictive performance. The concentration–area fractal model was used to outline the prospective areas predicted by the EL algorithms, clarifying areas with very high prospectivity for gold mineralization in the study area.