R-mode factor analysis of stream sediment geochemical data: A multivariate statistical approach for critical mineral exploration in the Bundelkhand Craton, India

Abstract

The Bundelkhand Craton, though relatively underexplored compared to other Archean cratons of India, exhibits geological and geochemical similarities with mineralised terrains globally, suggesting its potential to host economic mineralisation. In 21st-century exploration, where large geochemical datasets are available, robust statistical methods are essential to decode intricate patterns hidden within these data. This study applies R-mode factor analysis to centered log-ratio transformed stream sediment geochemical data (2808 samples, 62 elements) from the central Bundelkhand Craton to identify mineralisation-related signatures. Three key factors were extracted, explaining 52% of the total variance: (1) a lithological factor (26%) reflecting granitoid-mafic dyke assemblages, (2) a rare earth element (REE)-rare metal factor (20%) linked to potassic granitoids, and (3) a gold-bismuth-selenium factor (6%) spatially associated with shear zones. The centered log-ratio transformation effectively addressed compositional data constraints, while varimax rotation produced interpretable factors aligned with known geology. Spatial analysis revealed high-priority exploration targets, viz. REE anomalies in the south correlate with alkaline granitoids, while gold-bismuth-selenium anomalies along the Bundelkhand Tectonic Zone and Raksha Shear Zone confirm structurally controlled gold mineralisation. Scandium anomalies, coinciding with Fe-Mg-Ca-rich zones, indicate mafic-ultramafic intrusions. These findings not only validate historical gold occurrences but also reveal new critical mineral potential (Indium, Thalium and Scandium) in the craton. The study demonstrates how multivariate statistics, when integrated with geological knowledge, can transform regional geochemical data into actionable exploration targets. The methodology provides a replicable framework for assessing mineral potential in under-explored cratons, supporting India’s strategic mineral security initiatives.