Year: 1996
Type: report
Abstract: the southeast margin of the Colorado Plateau, and the Raton Basin is between the Sangre de Cristo Mountains and the High Plains; both basins extend into Colorado.The remain ing small coal fields in the state are in the Southern Rocky Mountains and northern Basin and Range physiographic provinces.Outlying fields adjacent to the San Juan Basin are the Datil Mountains, Salt Lake, Tierra Amarilla, and Rio Puerco fields.Coal fields outside the major basins are: the Cerrillos field southeast of Santa Fe, the Hagan and Tijeras fields northeast of Albuquerque on the east side of the Sandia Mountains, the Jornada del Muerto and Carthage fields southeast of Socorro, the Sierra Blanca field (coal-bearing outcrops encir cling Sierra Blanca) northwest of Ruidoso, and the Engle field east of Truth or Consequences.Besides the defined coal fields, thin Cretaceous coal beds in the southern San Andres Mountains, northeast of Las Cruces, and in the northeast corner of the state were used locally for home fuel before 1900.Pennsylvanian coal crops out in north-central New Mexico at several localities near and in Santa Fe, southeast of Taos, northwest of Las Vegas, and north of Pecos and is in the subsurface in southeast New Mexico (Shomaker et al., 1971, pp.177-179).These beds are some of the westernmost Pennsylvanian-age coals in the United States. Coal-bearing rocksSan Juan Basin coal, Late Cretaceous in age, is concen trated in three major coal-bearing sequences.They are, in ascending order, the Crevasse Canyon, Menefee, and Fruitland Formations.The Raton field has two coal-bearing sequences, the Vermejo and Raton Formations (Pillmore, 1969).The Vermejo Formation coal and lower coal zone within the Raton Formation are Late Cretaceous; coal in the upper Raton Formation is early Tertiary in age.In some areas, the Dakota Sandstone (early Late Cretaceous) con tains thin coal beds and coal laminae, but these have been mined only in a few localities and on a small scale.Most of the small coal fields outside the major basins are within out crops of the Mesaverde Group that are equivalent to the Menefee, Crevasse Canyon, or Ires Hermanos Formation. Structural geology of the coal-bearing basinsand other areas Jhe two major coal-bearing basins have simple geologic structure.Minor faulting occurs in both the Raton and San Juan Basins.Except along the steeper flanks, the dip of beds in most of the coal-bearing areas ranges from 2 ° to 6 ° .Several smaller coal fields in New Mexico are within or on the edge of the Rio Grande rift, which is marked by many faults, steeply dipping beds, and Cenozoic igneous activity.Igneous intrusions in the Cerrillos field have metamor phosed nearby Cretaceous coal to semianthracite and anthracite.Both the Datil Mountains and Sierra Blanca fields have thick layers of volcanic rocks overlying large areas of the coal-bearing strata.Extensive faulting and intrusive dikes have interrupted the coal-bearing units in the Sierra Blanca and Cerrillos fields.The Rio Puerco and Carthage fields are cut by many faults that create small blocks that contain fragmented coal-bearing sequences.The San Juan Basin is roughly an asymmetric circular structural depression that is deepest in the northeastern part of the basin.Cretaceous and early Tertiary strata dip steeply into the basin along the Hogback monocline to the north west and along the Archuleta arch and Nacimiento uplift to t 1
DOI: 10.58799/rm-20
Author: Gretchen K. Hoffman
Institution: New Mexico Bureau of Geology and Mineral Resources
Language: English
Subfield: Geology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
OpenAlex ID: W4385436966