The effects of coalification and paleoenvironment on aliphatic and aromatic CH contents in the Lower Kittanning coal seam

Abstract

Absorption spectra for 33 whole-seam channel samples and 24 vitrinite concentrates of the Lower Kittanning coal seam in western Pennsylvania and eastern Ohio were obtained by Fourier transform infrared (FTIR) analysis. Absorption areas for aliphatic and aromatic functional groups were calculated and compared to selected parameters of coalification in bivariate and multivariate statistical analyses. The aliphatic CH 3 and lone CH contents show weak correlations with coalification, whereas the correlations for aliphatic CH 2 and all aromatic CH groups are stronger. A secondary paleoenvironmental control over the concentrations of aliphatic CH 3, CH 2 and CH is suggested by trends on isopleth maps which show lateral variability of these components. These maps suggest that paleotopography, which influenced the distribution of marine and fresh-water sediments and their associated flora, was an important control in aliphatic concentrations. Statistical analysis indicates that the variability of aromatic CH may be entirely rank-controlled.