FLUORESCENCE INTENSITY AND ALTERATION OF COAL MACERALS AND THEIR RELATION TO COALIFICATION

Based on the measurements of fluorescence intensity and alteration on a rank series of coals from China, the process of coalification rangin g from peat to early medium volatile bituminous coal can be divided in to four rank stages. The boundaries between adjacent stages lie at the vitrinite reflectances of 0.30%, 0.55% and in the range of 0.80-0.90% Rm, where striking fluorescence changes or jumps take place. The jump at 0.3% R m, which has not been reported before, marks the boundary b etween soft and hard brown coals. The other boundaries correspond to t he first and second coalification jumps described by Teichmuller and D urand (1983), and can be compared with the oil birth line and maximum generation. Fluorescence intensity of both huminites/vitrinites and sp orinites generally decreases with increasing rank. Based on the correl ation equations between vitrinite reflectance and fluorescence intensi ty established in this study, it is possible to predict coal rank or t hermal maturity of organic matter with fluorescence intensity analysis . While the huminites/vitrinites and sporinites display a similar alte ration rank trend: from negative, through positive and dual and negati ve again, at any given rank, the alteration patterns of sporinites and vitrinites are different from each other. With increasing rank, the c hange of alteration pattern of the huminites/vitrinites always takes p lace earlier than that of the sporinites.