RT Journal Article T1 Petrografía de los carbones cantabrienses (Carbonífero sup.) del Grupo Cea de la Cuenca Guardo-Valderrueda (León-Palencia) T1 Petrographic characterization of Cantabrian coals (Upper Carboniferous) of the Cea Group in the Guardo-Valderrueda Basin (León-Palencia) A1 Llorens, T. A1 Suárez Ruiz, I. A1 Colmenero, Juan Ramón AB The petrographic analysis of the coals of Guardo-Valderrueda basin (Cantabrian Mountains) shows ranksvarying from bituminous coals to meta-anthracite. Vitrinite Group dominates the maceral composition,with low Inertinite and scarce Liptinite contents. The presence of natural coke and pyrolytic carbon inmany samples indicates an important thermal alteration, mainly due to Variscan tectonism and Permicigneous activity YR 2006 FD 2006 LK http://hdl.handle.net/10272/8617 UL http://hdl.handle.net/10272/8617 LA spa DS Repositorio Institucional de la Universidad de Huelva RD 31 may 2026