PETROLOGICAL AND GEOCHEMICAL RESEARCH ON COALS OF THE IBAR-BASIN (YUGOSLAVIA)

The Ibar-basin, situated in the southwest of Serbia, contains several small coal basins of Tertiary age. The rank of the different coals was studied in the past and was determined again in this paper. Vitrinite reflectance (R(r)), fluorescence measurements of extracts and the liptinite maceral exsudatinite, as well as organic-geochemical investigations have shown a higher rank for the northernmost deposit of Usce (high volatile bituminous A coal) and lower rank in the deposits situated in the centre of the basin near Tadenje and in the south at Jarando, where the coal is of high volatile bituminous B/A rank. This relatively high rank for Tertiary coals is due to thermometamorphism. The petrography and geochemistry of Tadenje coal shows an extraordinary composition. This is explained by relatively enhanced oxidizing conditions during deposition. The low rank of the kerogen within the magnesite of Bela Stena in the south of the Ibar-Basin indicates that the magnesite deposition is younger than the peat accumulation. The magnesite is less affected by the andesite and dazite intrusions than the coal.