New interpretation of coalfield tectonic evolution: from coal-forming basins to coal-bearing tectonic units

The remarkable characteristics of coalfield structure of China are the various types of coal-forming basins and the late intensive reformation of coal series, most of coal-forming basins underwent strong destruction and the present distribution of coal series is different far from the original coal basin. Based on the research of coal-forming basin, this paper established a comprehensive classification scheme of coal-forming basin and divided the types of coal-forming basin during main coal-forming stages of China. The concept of coal-bearing tectonic units is adopted to indicate today's occurrence characteristics of coal series, and the formation and evolution of coalfield structure framework can be understood as a process that coal-forming prototype basin experienced reformation of varying degrees to form present coal-bearing tectonic units. Since late Paleozoic, the Chinese continent has experienced four major tectonic cycles, i.e. Hercynian movement, Indosinian movement, Yanshan movement, and Himalayan movement. And the coal-forming basins of different type formed in main coal-forming stages went through the reformation of different degrees during the multiple tectonic movements. The prototype basins were destroyed, superimposed and inverted, coal series in basin have been deformed, displaced and metamorphosed. By that, coal-forming basins were segmented into coal-bearing tectonic units with different scales and structural attribution, resulting in present occurrence status of coal resources.