Thermodynamic analysis and simulation of coal metamorphism in the Fushun Basin, China

Taking the Fushun Basin as an example, this paper analyses the relation of coal metamorphism to the normal geothermal field and additional geothermal field, and establishes the thermodynamical model for the paleogeothermal fi eld and corresponding coal metamorphism of the Basin. The 2-D simulation of the superimposition of coal geothermal metamorphism and telemagmatic therm al metamorphism has also been preliminarily accomplished. The computer simu lation results have shown that the coal, formed in the Paleogene, in the Fu shun Basin had an R-o,R-m value of only 0.3 +/- and the intrusion of diabas e sills in the Later Oligocene increased the coal rank to the low metamorph ism stage (R-o,R-m = 0.5-1.0%). It has been found in the simulation, that t he way in which the thermal flow in basement rock is controlled using the r esults from paleogeothermal structural analysis is obviously better than th e method in which a value is artificially selected for the thermal flow acc ording to the basin basement. In addition, the former can be used to study the variation of R-o,R-m itself, so it is also better than the method to pe rform back-confining analysis using R-o,R-m values. (C) 2000 Elsevier Scien ce B.V. All rights reserved.