Английская Википедия:Galisteo Formation
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The Galisteo Formation is a geologic formation in New Mexico. It contains fossils characteristic of the Bartonian stage of the Eocene epoch, Duchesnean in the NALMA classification.[1]
Description
The Galisteo Formation is primarily fluvial sandstone and mudstone, with small amounts of conglomerate, freshwater limestone, and sedimentary tuff. It crops out over a limited area between Sandia Crest and the southern Sangre de Cristo Mountains, with an outlier at the eastern feet of the San Miguel subrange of the Jemez Mountains. Its contact with the overlying Espinaso Formation is gradational.Шаблон:Sfn The formation rests on the Diamond Tail Formation in most locations where its base is exposed, but the Diamond Tail is not present in the exposures south of San Ysidro.Шаблон:Sfn The presence of Precambrian and Paleozoic clasts at the base of the Galisteo Formation suggests that the discontinuity separating it from the Diamond Tail is tectonic in origin.Шаблон:Sfn There are indications the formation itself experienced penecontemporaneous deformation, possibly due to renewed uplift of the southern Sangre de Cristo Mountains.Шаблон:Sfn The maximum thickness of the formation is Шаблон:Convert.Шаблон:Sfn
Paleocurrent directions indicate the sources of the sediments deposited in the formation came from the Brazos-Sangre de Cristo Geanticline to the northeast and the Nacimiento Mountains to the northwest. There are no indications of sediments from Sandia Crest to the south, suggesting that Sandia Crest was not uplifted until after the Eocene.Шаблон:Sfn The presence of Precambrian clasts in the upper part of the formation in the San Miguel Mountains was some of the first evidence for the existence of the Pajarito Uplift, a Laramide structure occupying what is now the southern Espanola Basin between the current locations of Los Alamos and Santa Fe that later foundered into the Rio Grande Rift.Шаблон:Sfn
The Galisteo Formation likely correlates with the El Rito Formation to the north of the Jemez Mountains.Шаблон:Sfn It may also correlate with the Tapicito Member of the San Jose Formation.Шаблон:Sfn
Paleontology
The most important fossil site in the Galisteo Formation, the Stearns quarry at Arroyo del Tuerto,Шаблон:Sfn contains numerous fossil remains of titanotheres dating to the Duchesnean Stage, about 42 to 38 million years ago. Petrified wood is also found in this area. The formation is otherwise largely barren of fossils.
Fossil content
The following fossils have been reported from the formation:[1]
Mammals
- Carnivora
- Glires
- Pantodonta
- Perissodactyls
- Placentalia
- Primates
- Theriiformes
History of investigation
The formation was first described by F.V. Hayden during the 1869 expedition to New Mexico and Colorado. He named the formation the Galisteo sand group and noted that its sandstone beds dipped from 5 to 50 degrees and varied in color from off-white to brick red. He could find no fossils other than petrified logs, some of which were enormous.Шаблон:Sfn
The formation originally included older beds separated from the rest of the formation by a significant disconformity. These were split off into the Diamond Tail Formation in 1997.Шаблон:Sfn
See also
References
Bibliography
- Шаблон:Cite web
- Шаблон:Cite book
- Шаблон:Cite journal
- Шаблон:Cite book
- Шаблон:Cite journal
- Шаблон:Cite journal
- Шаблон:Cite journal
- Шаблон:Cite journal
- ↑ 1,0 1,1 Galisteo Formation at Fossilworks.org
- Английская Википедия
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- Paleogene formations of New Mexico
- Eocene Series of North America
- Bartonian Stage
- Duchesnean
- Sandstone formations of the United States
- Tuff formations
- Fluvial deposits
- Paleontology in New Mexico
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