Preliminary report on rank of deep coals in part of the southern Piceance Creek basin, Colorado

Surface vitrinite reflectance study of the Uinta and Piceance basins and adjacent areas, eastern Utah and western Colorado — Implications for the development of Laramide basins and uplifts

“…Vitrinite reflectance maps have been generated for the CameoFairfield coal zone of the Upper Cretaceous Mesaverde Group (plate 2) in the Piceance basin (Freeman, 1979 (Nuccio and Johnson, 1983, 1989aChancellor andJohnson, 1986, 1988;Johnson and Nuccio, 1986) also have been published. Johnson and others (1987) estimated the positions of the 0.73-and 1.1-percent Rm thermal maturity levels in the Piceance basin and used these thermal maturity levels to approximately define the limits of the low-permeability Mesaverde gas accumulation.…”

“…Economically important coal zones are present in many of the regressive marine cycles, and some coal and carbonaceous shale are present throughout the fluvial part of the Mesaverde as well. Coal rank maps based on vitrinite reflectance have been generated for coal zones associated with marine regressive cycles (Freeman, 1979;Johnson, 1983, 1986), and many vitrinite reflectance profiles through the Mesaverde are available (Bostick and Freeman, 1984; Chancellor and Johnson, , 1988Johnson and Nuccio, 1986;Nuccio and Johnson, 1989a). The position of several key vitrinite reflectance levels has also been generally determined in the Piceance basin (Johnson and others, 1987).…”

Reserve estimates in western basins. Part 2: Piceance Basin

“…An independent study of coal rank was beyond the scope of this study and a map of coal rank at the base of the Cameo Fairfield coal zone published by Freeman (1979), Nuccio and Johnson (1983) was used to descriie the geographic variation in rank (Figure B-2). Coal ranks vary from sub-bituminous A and high-volatile C (sbA-hvCb) at the west and southwest basin margins to semi-anthracite in the deepest parts of the basin.…”