Specific types of coal macerals from orzesze and ruda beds from "pniówek" coal mine (upper silesian coal basin - Poland) as a manifestation of thermal metamorphism

Abstract

Subject of the research were coal samples from the seams of Orzesze and Ruda beds from "Pniówek" coal mine. All samples represent methabituminous coal B, which present high vitrinite content (V mmf > 60%). Optical character of vitrinite from all analyzed coal samples is biaxial negative and it is characterized by low differentiation of bireflectance. The experiments have shown that the coal rank of investigated samples is generally decreasing with increasing both depth of coal seams and the distance between sampling point and the Carboniferous roof. It may suggests inversion of coalification. Specific types of macerals, typical for thermally metamorphosed coals have been found for all analysed coal samples. It was found, presence of such components like: fluorescing bituminous substance (FBS) filling of cellular spaces in semifusinite, fusinite, and funginite; pseudomorphs after megaspores exhibiting strong bireflectance, and anisotropic semifusinite. Petrographic components with a structure similar to structure of coke and pyrolytic carbon were observed rarely. Presence of colotelinite grains which are visible darker, impregnated with bituminous substance and exhibiting weak fluorescence may be related with influence of temperature on coal. Carbonates occur as filling of cellular spaces in semifusinite, in examined coal samples and there are the effect of thermal alteration of coal.