Light reflectance of some Slovenian coals

Abstract

Coal deposits and occurrences of Slovenia have been arranged into 13 belts and adequately named. Mean random light reflectance measurements on huminite-vitrinite macerals of 34 occasional coal samples made possible their preliminary ranging by rank. The majority of coals occupy the reflectance intervals of lower lignitous and hypobituminous ranks. Two coals only are of higher rank. The measured reflectance and absolute age are positively related in general, with anomalous ranks standing out. The graph of reflectance versus estimated maximal depth of burial indicates variable paleogeothermic gradients. The coal rank — a function of temperature and time — could be conditionally used for stratigraphic purposes. The anomalous rank of some coals can be explained by local thermal effects of the Rupelian andesitic volcanism. The established coal ranks may be also applicable to preliminary assessment of hydrocarbon potential of the coal-bearing sediments.