Variations in coal maceral chemistry with rank advance in the German Creek and Moranbah Coal Measures of the Bowen Basin, Australia, using electron microprobe techniques B Colin R. Ward T , Zhongsheng Li, Lila W. Gurba 1 School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, 2052, Australia Received 1 January 2004; received in revised form 1 January 2005; accepted 6 February 2005 Available online 19 April 2005 Abstract Variations in the elemental composition of individual macerals in seams from the Permian German Creek and Moranbah Coal Measures in the Bowen Basin of Queensland have been studied over a wide range of coal ranks, using light-element electron microprobe techniques, to establish the coalification tracks of key macerals in a single coal-bearing interval from subbituminous through bituminous coal to anthracite. Vitrinite reflectance (Rv max ) in the seams studied increases from 0.39% in the western part of the basin to over 3.5% in the east, apparently due to increases in burial depth. The study extends significantly the rank range covered by previous work on elemental analysis of individual macerals in the Gunnedah Basin, and provides a more useful basis than whole-coal analysis to evaluate the performance of coals in different utilisation processes. The microprobe results show that the carbon content of the telocollinite increases dramatically from 66% to 90% as the vitrinite reflectance of the coals (Rv max ) increases from 0.39% to around 1.75%, but increases only slightly, from 90% to 91%, as Rv max increases from 1.75% to 3.52%. Oxygen decreases from around 26% to approximately 5% as Rv max increases from 0.39% to around 1.75%, and then decreases only very slightly into the anthracite range. The nitrogen content of the telocollinite in these coals also appears to decrease slightly with rank advance, and appears moreover to display a relatively abrupt drop at around 2% Rv max . This may be associated with the development of ammonium illite in the mineral matter. Organic sulphur in the telocollinite, on the other hand, seems to remain essentially constant with rank advance, at least in this particular succession. In contrast to vitrinite, fusinite and inertodetrinite have significantly higher but somewhat more constant carbon contents, varying only from around 81% to 93% C over the rank range studied. Oxygen in these macerals decreases from around 12% to a little over 2% with the same degree of rank advance. Sulphur and possibly nitrogen also appear to be significantly lower in fusinite and inertodetrinite than in the vitrinite of the same coal samples. Semifusinite is somewhat more variable in 0166-5162/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.coal.2005.02.009 B Paper presented at the 20th Annual Meeting of the Society for Organic Petrology, Washington, DC, September 2003. T Corresponding author. Fax: +61 2 9385 1558. E-mail address: C.Ward@unsw.edu.au (C.R. Ward). 1 Present address: Cooperative Research Centre for Coal in Sustainable Development, Kenmore, 4069, Australia. International Journal of Coal Geology 63 (2005) 117 – 129 www.elsevier.com/locate/ijcoalgeo