Sangre de Cristo Formation

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Sangre de Cristo Formation
Stratigraphic range: Pennsylvanian–Cisuralian
Sangre de Cristo Formation.JPG
A roadcut along Colorado State Highway 12 showing the formation
Type Formation
Sub-unitsCrestone Conglomerate Member
Overlies Minturn Formation
Thickness1,739 m (5,705 ft)
Lithology
Primary Sandstone, mudstone
Other Conglomerate, limestone
Location
Coordinates 38°03′54″N105°39′14″W / 38.065°N 105.654°W / 38.065; -105.654
Region Colorado, New Mexico
Country United States
Type section
Named for Sangre de Cristo Mountains
Named byHill
Year defined1899
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Sangre de Cristo Formation (the United States)
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Sangre de Cristo Formation (Colorado)
Crestone Conglomerate in Colorado Crestone Conglomerate in Colorado USA.jpg
Crestone Conglomerate in Colorado

The Sangre de Cristo Formation is a geologic formation in Colorado and New Mexico. It preserves fossils dating back to the late Pennsylvanian to early Permian.

Contents

Description

Sangre de Cristo Formation in road cut in Glorieta Pass, New Mexico Sangre de Cristo Formation villaneuva.jpg
Sangre de Cristo Formation in road cut in Glorieta Pass, New Mexico

The formation is divided into an informal lower member and an upper Crestone Conglomerate Member. The lower informal member consists of about 600–900 meters (2,000–3,000 ft) of red arkosic sandstone, conglomeratic sandstone, siltstone, and shale. These are arranged into fining upwards cycles. The Crestone Conglomerate Member consists of about 1,100–2,000 meters (3,600–6,600 ft) of red conglomerate, conglomeratic sandstone, sandstone, and minor siltstone and shale. [1]

The formation is exposed in the Sangre de Cristo Mountains in both southern Colorado and northern New Mexico. However, the exposures in the southeastern Sangre de Cristo Mountains were deposited in a distinct basin (the Rowe-Mora basin) rather than the central Colorado basin, lack the marine beds found in Colorado, and should probably be assigned instead to the Abo Formation. [2]

Fossils

The informal lower members contains sparse fossiliferous limestone beds containing crinoids, brachiopods, stromatolites, fusulinids, and conodonts. [1]

Outcrops near the headwaters of the Pecos River include tetrapod footprints, identified as Batrachichnus, Limnopus , Ichniotherium , Tambachichnium, Dimetropus, and Dromopus . Less identifiable specimens may be Matthewichnus, Notalacerta, and Hyloidichnus. The assemblage is consistent with a late Artinskian age. [3]

History of investigation

The formation was first described by Hills in 1899. [4] F.A.Melton described the unit in 1925 as the Sangre de Cristo Conglomerate and defined a Crestone Conglomerate Phase (later Crestone Conglomerate Member). [5]

Footnotes

  1. 1 2 Lindsey et al. 1985
  2. Lucas et al. 2015
  3. Voigt and Lucas 2015
  4. Hills 1899
  5. Melton 1925

See also

References