Organic geochemical characteristics of Mae Teep coal deposits, Thailand

Abstract

The organic geochemical data presented for sixteen rock samples including nine coals, five shales and two mudstones from Mae Teep coal mine located in Lampang province. The total organic carbon (TOC) content of the coal samples ranges from 30.12-73.71 wt.% whereas shale and mudstone values range between 4.81 and 19.49 wt.%. The extractable organic matter (EOM) of all studied samples, which is yielded from bitumen extraction, values between 313.3-9764 ppm representing good to excellent hydrocarbon-generation potential. The thermal maturity and organic matter type of the samples were determined from organic geochemical data. The thermal maturity of the samples is consistent with their being of immature stage. Gas chromatograms obtained from the samples are dominated by long chain n-alkanes and high Carbon Preference Index (CPI) values, indicating terrestrial organic matter input. The biomarker parameters obtained from mass spectrometer data on m/z 191 and m/z 217 indicate that the depositional environments are divided into three main environments: (1) coal seams are deposited in aquatic terrestrial environment under relatively oxic condition; (2) oil shale are deposited in aquatic terrestrial environment under relatively anoxic condition and; (3) mudstones are interpreted to be organic-lean sediment supply in terrestrial environment.