A compilation of new and previously published vitrinite reflectance (Ro) data from Carboniferous coals constitutes the most comprehensive map of reflectance across Great Britain. Values of Ro range from 0.38 to 3.29 %, recording an ambient thermal maturity in the early oil window (standard reference point for reflectance studies), modified by elevated heat flow in northern England and along the Variscan orogenic front. The map provides a context for other geological data sets.

Supplementary material:https://doi.org/10.6084/m9.figshare.c.4529969

Scientific editing by Veerle Vandeginste

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