Evaluation of geologic controls on geothermal anomalies in the Arkoma Basin, Oklahoma

Vitrinite-reflectance techniques were used to determine if there is a relationship between present geothermal gradient and coal rank in the Arkoma Basin. Three coal seams from high geothermal-gradient areas were compared with the same coal seams, respectively, from low geothermal-gradient areas. Samples were obtained from three core holes that were drilled in the high geothermal-gradient areas in Pittsburg and Haskell Counties, and three core holes that were drilled in the low geothermal-gradient areas in Latimer and Muskogee Counties. Nine additional coal samples were collected from active coal mines and one from an outcrop to supplement the core samples. The vitrinite-reflectance data indicates the present geothermal gradient did not produce the coal rank in the Arkoma Basin of Oklahoma. The coal rank is believed to have developed during the late Paleozoic, possibly in connection with the Ouachita orogeny. The coal isocarb maps suggest that the present geothermal-gradient pattern reflects the paleogeothermal gradient that produced the coal rank. Perhaps the intense folding and faulting associated with the Ouachita orogeny combined to transmit heat from the basement along an east-west thermal-anomaly zone through Haskell and Pittsburg Counties, Oklahoma. 60 refs., 16 figs., 3 tabs