Variation in reflectance and chemistry of vitrinite and vitrinite precursors in a series of Tertiary Coals, Arctic Canada

A continuous 3300 m thick sequence of coal measures from the Eureka Sound Group, Foshiem Peninsula, Ellesmere Island has been studied in order to document changes in chemistry of coals from 0.17 to 0.56% vitrinite reflectance (Ro) as well as to determine differences in chemistry between collinite and telinite and their precursor macerals. Electron microprobe, micro-FTIR, solid state 13C-CPMAS NMR and reflected light microscopy techniques were applied. For the series of coals studied, collinite has a slightly higher Ro than telinite; Ro values of both macerals give precise measures of organic maturation. Reflectance is a better maturation parameter than carbon content and aromaticity over the studied maturation range. NMR and FTIR spectra show distinct changes in chemistry between coals with Ro below and above 0.2%. In organic matter with Ro below 0.2%, distinct differences exist between samples with respect to both the relative proportions of cellulose and lignin and the relative abundance of individual cellulose varieties. Coals with Ro above 0.2% do not have measurable amounts of cellulose, and differences between samples are indicated by differences in aromaticity of the lignin component. FTIR spectra show that, in coals with Ro < 0.2%, there is more cellulose in telinite than in collinite. Cellulose is not present in coals with Ro > 0.2%, and the lignin component is more aromatic in collinite than in telinite. The differences between telinite and collinite are attributed to differences in chemistry of the primary plant material.