Santa Fe Group | |
---|---|
Stratigraphic range: Oligocene to Pleistocene, | |
Type | Group |
Sub-units | See text |
Overlies | Espinaso Formation |
Thickness | 5,000 m (16,000 ft) |
Lithology | |
Primary | Siltstone |
Other | Sandstone, conglomerate |
Location | |
Region | New Mexico Colorado |
Country | United States |
Extent | Rio Grande rift |
Type section | |
Named for | Santa Fe, New Mexico |
Named by | Hayden |
Year defined | 1869 |
The Santa Fe Group is a group of geologic formations in New Mexico and Colorado. It contains fossils characteristic of the Oligocene through Pleistocene epochs. The group consists of basin-filling sedimentary and volcanic rocks of the Rio Grande rift, and contains important regional aquifers.
The Santa Fe Group is widely defined as basin-filling sedimentary and volcanic rocks of the Rio Grande rift. [1] These range in age from late Oligocene to Pleistocene. The oldest formations in the group correspond to the earliest structural deformation associated with rifting. Geologic uplift of the region around the rift has ended deposition, and erosion in the Rio Grande river system has exposed many of the beds deposited earlier, often spectacularly, as in the badlands north of Santa Fe. [2] [3]
The formations in the group are divided into lower and upper sections. The lower Santa Fe Group was deposited in bolsons (closed arid basins) where streams drained into intermittent playa lakes surrounded by piedmont deposits eroded from basin-margin uplifts. The upper Santa Fe Group was deposited after integration of these basins into the ancestral Rio Grande, so that their drainage flowed toward southern New Mexico. Some geologists also define a middle section transitional between the upper and lower sections. [3]
Formations of the Santa Fe Group are defined in each basin of the Rio Grande rift, though some formations extend across multiple basins.
Upper Santa Fe Group:
The lower Santa Fe Group is present only in the subsurface in the San Luis Basin and has not been divided into formations. [5]
Upper Santa Fe Group:
Lower Santa Fe Group:
Upper Santa Fe Group:
Lower Santa Fe Group:
Upper Santa Fe Group:
Middle Santa Fe Group:
Lower Santa Fe Group:
Upper Santa Fe Group:
Lower Santa Fe Group:
Upper Santa Fe Group:
Lower Santa Fe Group:
G.K. Gilbert visited San Ildefonso Pueblo with the Hayden Survey in 1873 and found fossil mammal bones characteristic of the Pliocene. Some of these were sent to Othniel Marsh. Marsh's bitter rival, Edward Drinker Cope, arrived at San Ildefonso the next year and collected a number of Miocene reptile, bird, and mammal fossils. [13]
Childs Frick sent an expedition into the Tesuque area in 1924, and immediately recognized the paleontological potential of the Santa Fe beds. The Fricks Laboratory (merged with the Department of Vertebrate Paleontology of the American Museum of Natural History in 1968) carried out field work through 1972. Work prior to 1940 was careless about identifying exact source strata, though greater care was taken thereafter. [14] Most of the fossils came from the Pojoaque Member of the Tesuque Formation and were almost entire found within thin (0.5–3 m) maroon-red to pale green claystone to fine-grained siltstone beds of lithosome B. These are interpreted as small lacustrine deposits. [15]
Fossils found in the Santa Fe Group include the canids Hemicyon and Carpocyon webbi, the antilocaprids Cosoryx , Merycodus , and Ramoceros , chiroptera from the Vespertilionidae and Antrozoinae, the turtle Glyptemys valentinensis, and mastodonts. [16] [17]
The groundwater potential of the Santa Fe Group was recognized by Bryan Kirk in 1938, [18] and the Alamosa subbasin of the San Luis Valley, the central part of the Albuquerque Basin, and the southern Mesilla basin from Las Cruces to El Paso are now among the most productive groundwater reservoirs in the western United States. [19] In the Albuquerque area, this has produced significant drawdown of the water table, in some places exceeding 100 feet (30 m). [20] The aquifer continues to be studied to characterize the effects of new development, and resulting shifts in groundwater flow, on pollutants in the aquifer. [21]
Hayden gave the name "Santa Fe Marls" to the extensive sedimentary beds in the valley of the Rio Grande near Santa Fe during his 1869 survey of New Mexico and Colorado. He likened these to the badlands of South Dakota and correctly determined that they were upper Tertiary in age and were much younger than the Galisteo Formation beds which they overlie. He noted their great thickness, which he observed to be at least 1,500 feet (460 m). [22]
By 1936, the Santa Fe Formation had been traced from central New Mexico into southern Colorado. [23] Two years later, Bryan recognized that it extended at least from the San Luis Basin to beyond El Paso and was extensively faulted and deformed. He interpreted the formation as being deposited in a series of basins along an ancestral Rio Grande. [18] The formation was promoted to group rank in 1953 [24] and defined by Baldwin three years later as basin-filling sedimentary and volcanic rocks of the Rio Grande rift. [1]
Galusha and Blick advocated a much narrower definition of the Santa Fe Group in 1971. They restricted it to the Tesuque Formation and Chamita Formation in the Espanola basin, and specifically excluded the older Abiquiu and Zia Formation and younger Ancha Formation. [25] However, the broad 1956 definition by Baldwin has been widely accepted. [26] [27] [28] [29] [30] [31]
The San Luis Valley is a region in south-central Colorado with a small portion overlapping into New Mexico. The valley is approximately 122 miles (196 km) long and 74 miles (119 km) wide, extending from the Continental Divide on the northwest rim into New Mexico on the south. It contains 6 counties and portions of 3 others. It is an extensive high-altitude depositional basin of approximately 8,000 square miles (21,000 km2) with an average elevation of 7,664 feet (2,336 m) above sea level. The valley is a section of the Rio Grande Rift and is drained to the south by the Rio Grande, which rises in the San Juan Mountains to the west of the valley and flows south into New Mexico. The San Luis Valley has a cold desert climate but has substantial water resources from the Rio Grande and groundwater.
The Rio Grande rift is a north-trending continental rift zone. It separates the Colorado Plateau in the west from the interior of the North American craton on the east. The rift extends from central Colorado in the north to the state of Chihuahua, Mexico, in the south. The rift zone consists of four basins that have an average width of 50 kilometres (31 mi). The rift can be observed on location at Rio Grande National Forest, White Sands National Park, Santa Fe National Forest, and Cibola National Forest, among other locations.
The Brazos Mountains is a range in far northern Rio Arriba County, in northern New Mexico in the southwestern United States. The range is part of the Tusas Mountains, which extended slightly into Colorado. A high crest runs from the border with Colorado for over 20 miles (32 km) in a south-southeasterly direction. The high point of the range at 11,405 feet (3,476 m) is on Grouse Mesa, at the Brazos Benchmark. Two miles (3 km) to the southeast is the more distinctive Brazos Peak, at 11,288 feet.
The Caballo Mountains, are a mountain range located in Sierra and Doña Ana Counties, New Mexico, United States. The range is located east of the Rio Grande and Caballo Lake, and west of the Jornada del Muerto; the south of the range extends into northwest Doña Ana County. The nearest towns are Truth or Consequences and Hatch.
The Albuquerque Basin is a structural basin and ecoregion within the Rio Grande rift in central New Mexico. It contains the city of Albuquerque.
The Camp Rice Formation is a geologic formation in west Texas and southern New Mexico. It preserves fossils of the Pliocene-Pleistocene. These include the distinctive Tonuco Mountain Local Fauna.
The Chamita Formation is a geologic formation in north-central New Mexico. It preserves unique fossils dating back to the Neogene period. The presence of volcanic ash beds in the formation, which can be radiometrically dated, gives the absolute age of the fossils, which is valuable for establishing the geologic time scale of the Neogene.
The Popotosa Formation is a geologic formation in New Mexico. It preserves fossils dating back to the Neogene period. These include the Socorro flora, notable for its fine preservation of plant reproductive structures.
The Rincon Valley Formation is a geologic formation found in the Rincon Valley of New Mexico. It preserves fossils dating back to the Miocene epoch and records a time when the valley was a closed basin, just before being integrated into the ancestral Rio Grande River.
The Tesuque Formation is a geologic formation in north-central New Mexico, United States. The formation provides an unusually complete record of the evolution of mammals during the Miocene epoch.
The Zia Formation is a geologic formation in the southwestern Jemez Mountains and northwestern Santo Domingo basin. It contains vertebrate fossils that date it to early to middle Miocene in age.
Robbie Rice Gries is an American petroleum geologist who was the first female president (2001–02) of the American Association of Petroleum Geologists (AAPG), president of the Geological Society of America (2018–19), and founder of Priority Oil & Gas LLC. Gries is noted to have made some influential progress for women in this field. In 2017, Gries published the book titled Anomalies—Pioneering Women in Petroleum Geology: 1917-2017. Gries is recognized as an unconventional thinker when approaching geological concepts and applications.
The geology of New Mexico includes bedrock exposures of four physiographic provinces, with ages ranging from almost 1800 million years (Ma) to nearly the present day. Here the Great Plains, southern Rocky Mountains, Colorado Plateau, and Basin and Range Provinces meet, giving the state great geologic diversity.
The Tanos Formation is a geologic formation in central New Mexico. It is estimated to be about 25 million years in age, corresponding to the Oligocene epoch.
The Ancha Formation is a geologic formation found near Santa Fe, New Mexico. It is estimated to be between 1 and 3 million years in age, corresponding to the late Pliocene and Pleistocene.
The Arroyo Ojito Formation is a late Miocene geologic formation exposed near Albuquerque, New Mexico. It records deposition of sediments in the Albuquerque Basin of the Rio Grande Rift after full integration of the Rio Grande through the basin.
The Blackshare Formation is a geologic formation exposed in the Hagan Basin west of the Ortiz Mountains of New Mexico. It is estimated be to of Miocene age.
The Servilleta Basalt or Servilleta Formation is a geologic formation that underlies most of the Taos Plateau of northern New Mexico. It has a radiometric age of 3.6 to 4.5 million years, corresponding to the Pliocene epoch.
The Picuris Formation is a geologic formation exposed in the eastern flank of the Rio Grande rift in northern New Mexico. It was deposited from the late Eocene to Miocene epochs.
The Espanola basin is a structural basin in northern New Mexico. It is located in the Rio Grande watershed and is part of the Rio Grande rift. The definition of its boundaries is not fully settled, but the basin is usually defined such that it includes the cities of Santa Fe, Los Alamos, and Espanola.