Rincon Valley Formation Stratigraphic range: Miocene | |
---|---|
Type | Formation |
Unit of | Santa Fe Group (geology) |
Underlies | Camp Rice Formation |
Overlies | Hayner Ranch Formation |
Thickness | 610 meters (2,000 ft) |
Lithology | |
Primary | Sandstone, mudstone, conglomerate |
Other | Gypsum |
Location | |
Coordinates | 32°35′19″N106°58′02″W / 32.588750°N 106.967225°W |
Region | New Mexico |
Country | United States |
Type section | |
Named for | Rincon Valley |
Named by | Seager et al. |
Year defined | 1971 |
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 [1] and records a time when the valley was a closed basin, just before being integrated into the ancestral Rio Grande River. [2]
The formation consists of pink to reddish-brown gypsiferous claystone and siltstone; conglomerate; and conglomeratic sandstone. [1] The thickness is 610 meters (2,000 ft). [2] The formation is exposed in the badlands bordering the Rio Grande valley north of Las Cruces, New Mexico. It grades below into the Hayner Ranch Formation and unconformably underlies the Camp Rice Formation. [1] It is interbedded with flows of the Selden Basalt Member with a radiometric age of 9.6 million years. [3]
The formation consists of two facies representing different depositional environments. The first is a fine-grained gypsiferous slope-forming facies interpreted as playa deposits in a closed basin. This contains gypsum beds up to 2 feet (0.61 m) thick. The second facies, which forms the upper 180 feet (55 m) of the formation, is a more resistant poorly sorted conglomerate interpreted as piedmont deposits, eroded from the uplifts that bordered the basin. [1]
The formation is interpreted as the final filling of the closed basin. [1] During its deposition, tectonic deformation continued along the Rio Grande rift, of which the basin was a part. Some 854 meters (2,802 ft) of displacement occurring along the Caballo Mountains border faults on the west side of the basin. The Sierra de las Uvas and Dona Ana Mountains to the south and southeast were first thrown during deposition of the formation, with a displacement of about 549 meters (1,801 ft) on the bounding fault of the Sierra de las Ulvas block. [2]
Study of this and other Cenozoic formations in the region has helped provide evidence for four episodes of block faulting in the Rio Grande rift in the last 35 million years. [2]
The formation is largely devoid of fossils. However, a single carpal bone of the rhinoceros Teleoceras fossiger has been recovered from the formation, of Hemphillian age, in agreement with the age of the formation from radiometric dating. [3]
The formation was first defined by W.R. Seager and coinvestigators in 1971, and assigned to the Santa Fe Group. [1]
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 kilometers. 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 Potrillo volcanic field is a monogenetic volcanic field located on the Rio Grande Rift in southern New Mexico, United States and northern Chihuahua, Mexico. The volcanic field lies 22 miles (35 km) southwest of Las Cruces, and occupies about 4,600 square kilometers (1,800 sq mi) near the U.S. border with Mexico.
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 Pliocene to Late Neogene Bidahochi Formation lies at an elevation of about 6,300 feet (1,920 m) to 6,600 feet (2,012 m) at the southeast of the Colorado Plateau; the deposits are from Hopi Lake, and the deposits extend southwards to the region at the north perimeter of the White Mountains of central-east Arizona. Bidahochi Lake is thought to have been a single "large lake, or several shallow, and ephemeral ones." Various fossil types are found; also bird trackways.
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 Palomas Formation is a geologic formation exposed in the southern Rio Grande rift of New Mexico. It preserves fossils dating back to the Pliocene to Quaternary.
The Abiquiu Formation is a geologic formation found in northern New Mexico. Radiometric dating constrains its age to between 18 million and 27 million years, corresponding to the late Oligocene to Miocene epochs.
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 Sierra Ladrones Formation is a geologic formation exposed near the Rio Grande river valley in New Mexico. It preserves fossils of Pliocene to Pleistocene age.
The Palm Park Formation is a geologic formation in southern New Mexico. It preserves fossils dating back to the Eocene epoch.
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 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 El Rito Formation is a geologic formation in New Mexico dating to the Eocene epoch.
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 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 Spears Group is a group of geologic formations exposed in and around the northeast Mogollon-Datil volcanic field of southwestern New Mexico. It has a radiometric age of 33 to 39 million years, corresponding to the Eocene to Oligocene epochs.
The Hayner Ranch Formation is a geologic formation found near the San Diego Mountains of New Mexico. It is estimated to have been deposited during the Miocene epoch.
The Love Ranch Formation is a geologic formation in southern New Mexico. It was likely deposited during the Eocene epoch.
The Bell Top Formation is a geologic formation in southern New Mexico. Radiometric dating of surrounding tuffs indicate that it was deposited in the Oligocene epoch.