Geochemical variations in coal are well documented, occurring in individual seams, between different seams within coal-bearing sequences, and between coal basins in similar and different geologic settings. This chapter demonstrates that distinctive geochemical patterns occur in the coal deposits formed in each of four tectonic settings of the western Canadian Cordillera.

Highest mean major and trace element concentrations are most common in the Comox, Hat Creek, northeast Rocky Mountain, and Byron Creek coal deposits. Lowest values are most common in the Tulameen and southeast Rocky Mountain coals. Regional geochemical trends were identified on the basis of t-tests for differences in means. The Insular coal deposits are characterized by high CaO, Sb, and Sr, intermediate ash, Al₂O₃, Co, and Mo, and low Br, Th, Zn, and Zr. Intermontane coals exhibit high MnO, intermediate S, and low Ba and W. The northeast Rocky Mountain deposits each have high U, intermediate Co, Cl, and Zr, and low S. Typical patterns in the southeast Rocky Mountain coals include intermediate MgO and Zn, and low Al₂O₃, Co, and Rb.

Factors that control these patterns include depositional environment, rank, source rocks, rates of sedimentation, and mineral matter. Tectonic setting directly or indirectly influences all of these variables, and is therefore considered to be a dominant control on regional geochemical patterns in the Canadian Cordillera.