Comparison of two petrographic methods for determining the degree of anomalous vitrinite reflectance

Three Australian Permian bituminous coals from well-documented geological settings chosen to cover a range of rank, and orthohydrous, subhydrous and perhydrous vitrinite compositions, were used to compare and contrast two petrographic methods for correcting anomalies in vitrinite reflectance (VR) due to compositional variation. One of the methods (fluorescence alteration of multiple macerals (FAMM(TM))) is based on the fluorescence alteration properties of coal macerals, and the other on paired measurements of reflectance and fluorescence intensity. The methods are only applicable to fresh (unoxidised) coals or dispersed organic matter (DOM). Both methods use a reference 'normal' orthohydrous telovitrinite line on which results from perhydrous or subhydrous samples are projected to obtain the equivalent reflectance of orthohydrous telovitrinite. The results of the two methods on the test samples are similar but they differ in detail. (C) 2002 Elsevier Science B.V. All rights reserved.