STRUCTURAL CONTROL AND GEOCHEMICAL EVOLUTION OF Pb-Zn-Cu MINERALIZATION: A MULTIVARIATE STATISTICAL APPROACH USING CENTRED LOG-RATIO (CLR) TRANSFORMATION AND PRINCIPAL COMPONENTS ANALYSIS

Abstract

The Saiya-Shokobo and Tongolo alkaline ring complexes of North-Central Nigeria host significant Pb-Zn-Cu mineralization. However, the structural controls and paragenetic evolution of these deposits remain poorly understood. This study integrates detailed structural mapping with Compositional Data Analysis (CoDA), employing the Centred Log-Ratio (CLR) transformation and Principal Component Analysis (PCA) of lithogeochemical data to distinguish discrete mineralization events within the Younger Granite and basement rock units. Structural analysis identifies dominant NNE-SSW, NNW-SSE, NE-SW, and N-S trends, indicating that reactivated Pan-African shear zones acted as major conduits for hydrothermal fluids. CLR-PCA further demonstrates that mineralization-related signatures are concentrated in lower-eigenvalue components beyond the lithological background represented by PC1–PC3. In the Younger Granites, PC5 (λ = 0.66) defines a Cu-Pb association interpreted as evidence of telescoped hydrothermal activity involving successive high- and low-temperature fluid pulses. In contrast, PC4 (λ = 0.60) within the basement rocks is characterized by a distinct Pb signature, suggesting pre-magmatic metal enrichment. These findings support a dual-source metallogenic model in which the Nigerian basement served as a pre-enriched metal reservoir, subsequently overprinted by magmatic-hydrothermal fluids associated with the anorogenic Younger Granite event. The study demonstrates the effectiveness of CoDA-based multivariate analysis for resolving previously unresolved paragenetic stages in polymetallic hydrothermal systems.