Formation of nanoporous pyrobitumen residues during maturation of the Barnett Shale (Fort Worth Basin)

► Detection of geochemical heterogeneities at the nanoscale within gas shale samples. ► Chemical and structural evolution of type II kerogen with increasing maturity. ► In-situ insights into the fate of bitumen as a response to maturation. ► Identification of nanoporous pyrobitumen within samples of gas window maturity.