Big Rock Formation | |
---|---|
Stratigraphic range: | |
Type | Formation |
Unit of | Vadito Group |
Underlies | Burned Mountain Formation |
Overlies | Lower Vadito Group |
Thickness | 70 m (230 ft) |
Lithology | |
Primary | Metaconglomerate |
Other | Quartzite |
Location | |
Coordinates | 36°32′59″N106°05′15″W / 36.5496°N 106.08744°W |
Region | Tusas Mountains, New Mexico |
Country | United States |
Type section | |
Named for | Big Rock ( 36°33′29″N106°04′16″W / 36.558°N 106.071°W ) |
Named by | F. Barker |
Year defined | 1958 |
The Big Rock Formation is a formation that crops out in the Tusas Mountains of northern New Mexico. Detrital zircon geochronology gives a maximum age for the formation of 1665 Mya, corresponding to the Statherian period.
The Big Rock Formation consists of a lower conglomerate member with minor micaceous quartzite and an upper quartzite member. The conglomerate is a medium to dark gray quartz pebble metaconglomerate with minor quartzite beds, interpreted as braided alluvial deposits. The pebbles are mostly of light gray quartz but with some ferruginous chert. Pebble sizes are from 1 to 20 cm and the pebbles are systematically elongated. Crossbedding is pervasive. [1] Flattened felsic clasts may be metamorphosed pumice. [2] It is exposed in the central Tusas Mountains, where it is distinctive enough to be an important stratigraphic marker bed. Its thickness is typically 60 meters (200 feet). [3]
Detrital zircon geochronology yields a minimum age for the source regions of 1665 Mya, consistent with the formation being deposited in an extensional basin (the Pilar basin) opened during the transition from the Yavapai orogeny to the Mazatzal orogeny. [4]
Based on clast deformation, the formation has been compressed 55 percent during folding, while being extended 10 percent parallel to the strike and 65 percent parallel to the dip. This assumes the clasts were not imbricated in the original deposit. [5]
The Big Rock Formation lies above the undivided lower Vadito Group and below the Burned Mountain Formation. It was long thought to correlate with the Marquenas Formation, [3] but Marquenas Quartzite has been found via detrital zircon geochronology be much younger. [4]
The formation has been interpreted as a beach gravel [6] or as a high-energy fluvial deposit associated with the Pilar basin of the Yavapai orogeny. [4]
The unit was originally designated as the Big Rock conglomerate member of the Kiawa Mountain Formation by Fred Barker in 1958, during the mapping of the Las Tablas quadrangle. [1] It was designated as a formation within the Vadito Group by Bauer and Williams in their sweeping revision of northern New Mexico Precambrian stratigraphy in 1989. [3]
The Manzano Group is a group of geologic formations in central New Mexico. These have radiometric ages of 1601 to 1662 million years (Ma), corresponding to the late Statherian period of the Paleoproterozoic.
The Waits River Formation (WRF) is a late Silurian to early Devonian limestone containing lesser amounts of phyllite and schist. It is located in the northern Appalachian Mountains of North America. It ranges from Long Island Sound in Connecticut to the Gulf of St. Lawrence in Quebec (about 1,000 km), and its width ranges from 10–50 km. It is part of the Connecticut Valley–Gaspé Trough, which is present in eastern and northeastern Vermont.
The Mazatzal orogeny was an orogenic event in what is now the Southwestern United States from 1650 to 1600 Mya in the Statherian Period of the Paleoproterozoic. Preserved in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1700-1600 Mya age Mazatzal island arc terrane with the proto-North American continent. This was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
The Yavapai orogeny was an orogenic (mountain-building) event in what is now the Southwestern United States that occurred between 1710 and 1680 million years ago (Mya), in the Statherian Period of the Paleoproterozoic. Recorded in the rocks of New Mexico and Arizona, it is interpreted as the collision of the 1800-1700 Mya age Yavapai island arc terrane with the proto-North American continent. This was the first in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
The Picuris orogeny was an orogenic event in what is now the Southwestern United States from 1.43 to 1.3 billion years ago in the Calymmian Period of the Mesoproterozoic. The event is named for the Picuris Mountains in northern New Mexico and interpreted either as the suturing of the Granite-Rhyolite crustal province to the southern margin of the proto-North American continent Laurentia or as the final suturing of the Mazatzal crustal province onto Laurentia. According to the former hypothesis, this was the second in a series of orogenies within a long-lived convergent boundary along southern Laurentia that ended with the ca. 1200–1000 Mya Grenville orogeny during the final assembly of the supercontinent Rodinia, which ended an 800-million-year episode of convergent boundary tectonism.
The Moppin Complex is a Precambrian geologic complex found in the Tusas Mountains of northern New Mexico. It has not been directly dated, but is thought to be Statherian based on a minimum age of 1.755 Gya from radiometric dating of magmatic intrusions.
The Vadito Group is a group of geologic formations that crops out in most of the Precambrian-cored uplifts of northern New Mexico. Detrital zircon geochronology and radiometric dating give a consistent age of 1700 Mya for the group, corresponding to the Statherian period.
The Burned Mountain Formation is a geologic formation that crops out in the Tusas Mountains of northern New Mexico. It has a U-Pb radiometric age of 1700 Mya, corresponding to the Statherian period.
The Glenwoody Formation is a geological formation that is exposed in the cliffs southeast of the Rio Grande Gorge near the town of Pilar and in a few other locations in the Picuris Mountains. Its minimum age from detrital zircon geochronology is 1.693 Mya, corresponding to the Statherian period.
The Hondo Group is a group of geologic formations that crops out in most of the Precambrian-cored uplifts of northern New Mexico. Detrital zircon geochronology gives a maximum age for the lower Hondo Group of 1765 to 1704 million years (Mya), corresponding to the Statherian period.
The Ortega Formation is a geologic formation that crops out in most of the mountain ranges of northern New Mexico. Detrital zircon geochronology establishes a maximum age for the formation of 1690-1670 million years (Mya), in the Statherian period of the Precambrian.
The Rinconada Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology establishes a maximum age for the Rinconada Formation of about 1723 Mya, placing it in the Statherian period of the Precambrian.
The Pilar Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. It has a radiometric age of 1488 ± 6 million years, corresponding to the Calymmian period.
The Piedra Lumbre Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology yields a maximum age of 1475 million years, corresponding to the Calymmian period.
The Marquenas Formation is a geological formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology gives it a maximum age of 1435 million years, corresponding to the Calymmian period.
The Tres Piedras Orthogneiss is a pluton in northern New Mexico. It has a U-Pb radiometric age of 1693 Mya, placing it in the Statherian period.
The El Rito Formation is a geologic formation in New Mexico dating to the Eocene epoch. It records a time when sediments were trapped in deep basins in western North America rather than being carried downstream to the Gulf of Mexico, so that sediments of this age in the western Gulf are mostly from the Appalachian Mountains.
The Ritito Conglomerate is a geologic formation in northern New Mexico dating to the Oligocene epoch.
The Uncompahgre Formation is a geologic formation in Colorado. Its radiometric age is between 1707 and 1704 Ma, corresponding to the Statherian period.
The Trampas Group is a group of geologic formations that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology yields a maximum age of 1475 million years, corresponding to the Calymmian period.