SPECTRAL FLUORESCENCE OF LIPTINITE MACERALS IN THE LOWER KITTANNING COAL AND OTHER PENNSYLVANIAN-AGE COALS

Vitrinite reflectance is the most commonly used method for measuring the thermal maturity of coals and shales; however, spectral fluorescence of liptinite macerals can be used in conjunction with vitrinite reflectance as an indicator of rank. Previous work on the Lower Kittanning Coal (Pennsylvanian) has shown variations in spectral fluorescence properties between liptinite macerals, and this study extends this work. The objective of this study was to assess the differences in fluorescence between various liptinite macerals with increasing rank within the Lower Kittanning Coal and other Pennsylvanian-age coals. This included establishing the average vitrinite reflectance (% R_r) for all samples and the average λ_max (wavelength of maximum fluorescence intensity), relative λ_max intensity, and Q (relative fluorescence intensity at 650 nm/ 500 nm) for samples with vitrinite reflectances between 0.5 and 1.3%. Liptinite macerals measured for spectral fluorescence included sporinite, cutinite, and resinite.

Preliminary results show that all three liptinite maceral types show an increase in λ_max with sporinite ranging from 567-642 nm, cutinite ranging from 570-662 nm, and resinite ranging from 553-616 nm. Resinite has a higher average relative λ_max intensity, and lower λ_max wavelength and Q compared to sporinite and cutinite in the Lower Kittanning Coal. Differences in spectral fluorescence properties may be influenced by changes in depositional environment and/or in plant precursors, the stage of development of the precursor materials, and their level of preservation, all of which could result in multiple populations of individual macerals.