Glenwoody Formation | |
---|---|
Stratigraphic range: | |
Type | Formation |
Unit of | Vadito Group |
Underlies | Hondo Group |
Overlies | lower Vadito Group |
Thickness | 300 m (980 ft) |
Lithology | |
Primary | Quartz–muscovite schist |
Other | Quartzite |
Location | |
Coordinates | 36°15′57″N105°47′44″W / 36.2659°N 105.7956°W |
Region | Picuris Mountains, New Mexico |
Country | United States |
Type section | |
Named for | Glenwoody mining camp |
Named by | Bauer and Williams |
Year defined | 1989 |
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. [1] Its minimum age from detrital zircon geochronology is 1.693 Mya, corresponding to the Statherian period.
The formation is composed of homogeneous feldspathic quartz-muscovite or quartz-eye schist containing quartz and feldspar megacrysts. Beds are typically light in color, ranging from pink to white to green. The modal composition is 50-70% quartz and 25-50% muscovite. It is notable for tourmaline-rich zones containing accessory fuchsite, purple muscovite, epidote, clinozoisite, zoisite, thulite, tremolite, sillimanite, kyanite, cyprine, allanite, and stibiotantalite. [1] It shows indications of high simple shearing strain. [2] It is at least 300 m (980 ft) in thickness. [3]
The formation is thought to be separated from the underlying lower Vadito Group by a significant unconformity. It is overlain by the Ortega Formation. [3]
Based on Uranium–lead dating of zircons, the age of the formation is 1.693 Mya, and it is interpreted as metamorphosed rhyolites from the waning stage of back arc rifting associated with the Yavapai orogeny. [3] It likely correlates with the Burned Mountain Formation in the Tusas Mountains. [2] [1]
The formation has a characteristic manganese-rich zone 30 meters thick near its upper contact with the Hondo Group that characterizes the uppermost Vadito Group throughout the region. It may have formed by syngenetic deposition from hydrothermal fluids, or a more general manganese enrichment of basin waters at the close of Vadito volcanism. [4] Another possibility is that it is a weathering horizon. Either possibility would make it an important regional time marker. [5]
The unit was included in the Ortega Quartzite by Arthur Montgomery in his study of the stratigraphy of the Picuris Mountains, [6] but it is metavolcanic rather than metasedimentary and so was redesignated the Glenwoody Formation of the Vadito Group by Bauer and Williams in their sweeping revision of the stratigraphy of northern New Mexico. The name refers to an old mining camp in the vicinity. [7]
In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into supergroups.
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 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 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 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 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 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 Picuris Mountains are a mountain range in northern New Mexico. They are considered a subrange of the Sangre de Cristo Mountains.
The Harding Pegmatite Mine is a former adit mine that extracted lithium, tantalum, and beryllium from a Precambrian pegmatite sill. It ceased operations in 1958 and its owner, Arthur Montgomery, donated it to the University of New Mexico, which runs the site as an outdoor geology laboratory with mineral collecting permitted on a small scale.
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 Joaquin quartz monzonite is a Mesoproterozoic pluton in northern New Mexico. Radiometric dating gives it an age of 1460 million years, corresponding to the Calymmian period.
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.