The identification of geochemical associations and anomalies related to mineralization is a critical aspect of mineral exploration. Conventional quantitative methods for determining these associations primarily involve correlating various geochemical elements with ore-forming elements and mineral deposits. However, these approaches often face challenges in elucidating the complex interrelationships among geochemical elements and are less effective in regions without known mineral deposits. The geographical detector has emerged as a powerful tool for detecting spatial heterogeneity and identifying key driving factors in mineralization processes. Since geochemical elements are regional variables characterized by spatial heterogeneity, the geographical detector is particularly suited for analyzing interactions among these elements. Additionally, unsupervised machine learning algorithms have proven adept at managing complex interrelations among geochemical elements and extracting deeper insights into mineralization patterns. Despite their advantages, these algorithms carry inherent systematic errors, which introduce uncertainties when relying on a single method, thereby increasing exploration risks. This study applies the geographical detector to the Nanling metallogenic belt, one of the most significant tungsten (W) polymetallic metallogenic belt in South China, to investigate the complex relationships between the ore-forming element W and other geochemical elements, as well as to identify associations pertinent to W polymetallic mineralization. Furthermore, 3 widely used unsupervised learning algorithms, including one-class support vector machines (OCSVM), isolation forest (IF), and deep auto-encoder neural networks (DAE), are employed to detect geochemical anomalies. A model averaging strategy is implemented to calculate the average and standard deviation of geochemical anomaly scores, providing robust anomaly predictions and the quantifying uncertainties associated with systematic errors across different algorithms. The enhanced prediction-area (P-A) plot is used to further assess these anomalies and their uncertainties. Key results include: (1) Geochemical elements such as Sn, Mo, Ag, and Bi have the largest impact on the enrichment of W, followed by Cu, Pb, and Be, with these elements often found in co-occurring or associated minerals linked to W polymetallic mineralization. Additional elements, including Nb, Th, Al2O3, U, As, F, Y, Cd, and Li, also contribute to W enrichment, reflecting the geochemical characteristics of plutons associated with W polymetallic deposits; (2) Element interactions are complex, with most showing nonlinear enhancement effects on W enrichment, which is critical for large-scale W mineralization in the region; (3) Among the machine learning algorithms, IF and OCSVM demonstrate superior and relatively stable performance, whereas DAE exhibits more scattered and disorganized anomaly detection, possibly due to limitation in the pixel-based anomaly recognition; (4) 6 prospective areas for mineral exploration have been identified based on geochemical anomaly scores and their associated uncertainties. This study not only introduces a novel methodology for quantitatively analyzing the complex relationships among geochemical elements, selecting relavant geochemical associations, and elucidating key geological processes related to mineralization. It also provides valuable insights for mineral exploration in the Nanling metallogenic belt.
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