Abstract Fossil-fuel fires in coal-bearing and bituminous complexes and associated combustion metamorphic transformations of sedimentary protoliths have been observed adjacent to many coal and oil deposits worldwide. The geologic and topographic features governing the distribution of fossil-fuel fires are similar for the majority of combustion metamorphic complexes. There are more than 40 such complexes in Europe, Asia, North America, Australia, and New Zealand. Combustion metamorphism is a striking geologic phenomenon, and the geologic history of Tertiary and Quaternary sedimentary basins prior to the ignition of any fossil fuels they contain determines the characteristics of future combustion metamorphic rocks. The evolutionary trend of combustion metamorphic systems is: formation of a fossil fuel → ignition and combustion of the fuel → decomposition and alteration of adjacent sedimentary strata and minerals, respectively → formation of pyrometamorphic rocks → retrograde alteration. The thermal energy for high-temperature and low-pressure metamorphism is supplied by the combustion of coal, gas, oil, or bitumen.