Contact metamorphism of coals in the Tunguska and Taimyr basins
Contact metamorphism is a whole complex of both coal and host rock alteration, originating from thermal, dynamic, and emanation influence of igneous rock's intrusions on coal-bearing deposits. There are a number of contact-metamorphic coals, ranging from free-burning coal to contact anthracite; natural coke, soot coal, and graphite can be found next to intrusions. Contact coal differs from isometamorphic coal of regional series by total absence of sinterability and coking power, reduced show of volatile matter, higher true density, often by lower calorific value and carbon content, as well as by higher moisture, porosity, and oxygen content. Being superimposed on an initial metamorphic zonation, contact metamorphism defines a final result of different quality coal distribution within Tungus and Taimyr basins