GEOCHEMICAL DIAGNOSTICS OF COAL GENOTYPES: METHOD, CALIBRATION, AND BASIN TYPOLOGY

This study presents a geochemical method for discriminating coal types based on vitrinite maceral composition (telinite vs. collinite), using trace element ratios normalized to a reference aluminum content of 1.5%. Analysis of 146 samples from 13 coal basins demonstrates that conventional geochemical proxies (V/Ni, Ni/Co, U/Th, V/Cr) are unreliable for paleoenvironmental interpretation, whereas intra-basin calibration with 5–7 petrographically characterized samples achieves >94% accuracy in distinguishing coal facies formed under oxidizing versus reducing conditions. The method is validated on independent datasets from the USA, Turkey, Norway, and China (>200 samples). Twelve geochemical basin types are identified, including a newly recognized Marine Li-B type characterized by elevated critical metals (Li, B, Sr) associated with marine-influenced depositional environments. For As-rich basins, V/As normalization is proposed; for high-Al basins (e.g., North China), normalization to Si is recommended. A two-stage approach combining local petrographic calibration with geochemical screening reduces exploration costs by 85–90%. The study contributes to coal facies analysis, critical metal resource assessment (Li, V, Sr), and provides recommendations for updating ICCP, ASTM, and ISO standards.