Coal metamorphism by igneous intrusion in the Raton Basin, CO and NM: Implications for generation of volatiles

The Raton Basin contains a series of Tertiary mafic dikes and sills that have altered millions of tons of coal to natural coke and may have played a minor role in generating some of the large coalbed methane resources currently being exploited in this region. Four outcrops within the Raton Basin were selected to investigate local coal rank elevation and volatile generation due to intrusive activity. Coal and organic shale samples were collected on traverses across meter-scale dikes and sills, and were analyzed for vitrinite reflectance, total organic carbon, bulk carbon isotopic ratios, and coke petrography.