Rio Grande Rift
Encyclopedia
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 in person at Rio Grande National Forest
, White Sands National Monument
, Santa Fe National Forest
, and Cibola National Forest
, among other locations.
The Rio Grande Rift has been an important site for humans for a long time, because it provides a N-S route that follows a major river, the Rio Grande river. The Rio Grande follows the course of the rift from southern Colorado to El Paso, where it turns southeast and flows into the Gulf of Mexico
. Important cities, including Albuquerque
, Santa Fe
, Taos
, Española
, El Paso
, and Ciudad Juarez
lie within the rift.
, and is not well defined.
Basin size generally decreases to the north in the rift, where the Española covers approximately 120 km north-south and 40 km east-west, and the San Luis is roughly 120 km by 80 km. These basins may contain smaller units within them, such as the Alamosa basin within the San Luis, which is bounded by the San Juan and Tusas mountains on the west and the Sangre de Cristo
mountain range in the east. The Albuquerque basin is the largest of the three basins, spanning 160 km north-south and 86 km east-west at its widest points. It is the oldest of the three major basins, and contains 7,350 m of Paleogene
clastic sediments deposited on Precambrian
basement. The southernmost Albuquerque basin contains pre-rift volcanic deposits
, while the central and northern portions contain volcanics erupted during rifting.
In regards to the southernmost Rio Grande Rift, the rift broadens and becomes physiographically indistinguishable from the Basin and Range province.
In cross-section, the geometry of the basins within the rift are asymmetrical half-grabens
, with major fault boundaries on one side and a downward hinge on the other. Which side of the basin has the major fault or the hinge alternates along the rift. The alternation between these half grabens occurs along transfer faults, which trend across the rift to connect the major basin-bounding faults and occur between basins or, in places, within basins. The Precambrian basement changes relief sharply in this area, from 8,700 m below sea level at the bottom of the Albuquerque basin to 3,300 m above sea level in the nearby Sandia Mountains
, which flanks the Albuquerque basin to the east. Flanking mountains are generally taller along the east side of the rift (although some of this relief may be Laramide
in origin). The thickness of the crust
increases to the north beneath the rift, where it may be as much as 5 km thicker than it is in the south. The crustal thickness underneath the rift is on average 30–35 km thick, thinner by 10–15 km than the Colorado Plateau on the west and the Great Plains to the east.
The rift is presently nearly tectonically quiescent, but significant deformation and faulting with offsets of many kilometers were responsible for its formation starting about 35 Ma. The largest-scale manifestation of rifting involves a pure-shear rifting mechanism, in which both sides of the rift pull apart evenly and slowly, with the lower crust and upper mantle (the lithosphere
) stretching like taffy
. This extension is associated with very low seismic velocities in the upper mantle above approximately 400 km depth associated with relatively hot mantle and low degrees of partial melting. This intrusion of the asthenosphere
into the lithosphere
and continental crust
is thought to be responsible for nearly all of the volcanism associated with the Rio Grande rift.
The sedimentary fill of the basins consists largely of alluvial fan
and mafic
volcanic flows. The most alkalic lavas erupted outside the rift. The sediments that were deposited during rifting are commonly known as the Santa Fe Group. This group contains sandstones, conglomerates
, and volcanics. Aeolian deposits are also present in some basins.
The Rio Grande Rift is intersected in northern New Mexico by the NE-SW trending Jemez Lineament, which is defined by aligned volcanic fields and several calderas in the area, including the Valles Caldera National Preserve in the Jemez Mountains
. The significance of the Jemez Lineament is unclear, however, it is not obviously related to the formation of the Rio Grande rift. The Colorado Plateau, to the west, includes the San Juan volcanic field
in the San Juan Mountains
.
The youngest eruptions in the rift region are in the Valley of Fires
, New Mexico and are approximately 5,400 years old. The Socorro, New Mexico
region of the central rift hosts an inflating mid-crustal sill-like magma body at a depth of 19 km that is responsible for anomalously high earthquake activity in the vicinity, including the largest rift-associated earthquakes in historic times (two events of approximately magnitude 5.8) in July and November 1906. Earth and space-based geodetic measurements indicate ongoing surface uplift above the at approximately 2 mm/year.
There is a body of magma called the Socorro Magma Body within the crust beneath Socorro, New Mexico
. The identification of this magma body came from extensive seismic data gathered in the area from the RISTRA
seismic program.
evolution is fairly complex. The fundamental change in the western margin of the North American plate from one of subduction
to a transform boundary
occurred during Cenozoic
time. The Farallon plate
continued to be subducted beneath western North America for at least 100 million years during Late Mesozoic
and early Cenozoic
time. Compressional and transpressional deformation
incurred by the Laramide Orogeny
lasted until about 40 Ma in New Mexico. This deformation may have been a result of the coupling between the subducting Farallon plate
and the overlying North American plate
. Crustal thickening occurred due to Laramide compression. After the Laramide Orogeny and until 20 Ma, a major period of volcanic activity occurred throughout the southwestern United States. Injection of hot magmas weakened the lithosphere and allowed for later extension of the region.
Cenozoic
extension started about 30 million years ago (Ma). There are two phases of extension observed: late Oligocene
and middle Miocene
. The first period of extension produced broad, shallow basins bounded by low-angle faults. The crust might have been extended as much as 50% during this episode. Widespread magma
tism in mid-Cenozoic
tine suggests that the lithosphere
was hot, the brittle-ductile transition was relatively shallow. In regards to the second period of extension, there is evidence that extension began earlier in the central and northern Rio Grande Rift than in the south.
It is suggested that the Colorado Plateau acts as a semi-independent microplate and one way of envisioning the creation of the Rio Grande Rift is for the simple rotation of the Colorado Plateau 1-1.5 degrees in a clock-wise direction.
Rift
In geology, a rift or chasm is a place where the Earth's crust and lithosphere are being pulled apart and is an example of extensional tectonics....
zone. It separates the Colorado Plateau
Colorado Plateau
The Colorado Plateau, also called the Colorado Plateau Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. The province covers an area of 337,000 km2 within western Colorado, northwestern New Mexico,...
in the west from the interior of the North American craton
Craton
A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...
on the east. The rift extends from central Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
in the north to the state of Chihuahua, Mexico
Chihuahua, Mexico
Chihuahua, Mexico, may refer to:* The State of Chihuahua in Mexico* The City of Chihuahua, Chihuahua, its capital...
in the south. The rift zone consists of four basins that have an average width of 50 kilometers. The rift can be observed in person at Rio Grande National Forest
Rio Grande National Forest
Rio Grande National Forest is a 1.86 million acre U.S. National Forest located in southwestern Colorado. The forest encompasses the San Luis Valley, which is the world's largest agricultural alpine valley, as well as one of the worlds largest high deserts located around mountains. The...
, White Sands National Monument
White Sands National Monument
The White Sands National Monument is a U.S. National Monument located about southwest of Alamogordo in western Otero County and northeastern Dona Ana County in the state of New Mexico, at an elevation of 4235 feet...
, Santa Fe National Forest
Santa Fe National Forest
The Santa Fe National Forest is a protected national forest in northern New Mexico in the Southwestern United States. It was established in 1915 and covers 1,567,181 acres . Elevations range from 5,300 feet to 13,103 feet at the summit of Truchas Peak, located within the Pecos Wilderness...
, and Cibola National Forest
Cibola National Forest
The Cibola National Forest is a United States National Forest in western and central New Mexico, USA. The forest also manages four National Grasslands that stretch from northeastern New Mexico eastward into the Texas Panhandle and western Oklahoma. It is administered by the United States Forest...
, among other locations.
The Rio Grande Rift has been an important site for humans for a long time, because it provides a N-S route that follows a major river, the Rio Grande river. The Rio Grande follows the course of the rift from southern Colorado to El Paso, where it turns southeast and flows into the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
. Important cities, including Albuquerque
Albuquerque, New Mexico
Albuquerque is the largest city in the state of New Mexico, United States. It is the county seat of Bernalillo County and is situated in the central part of the state, straddling the Rio Grande. The city population was 545,852 as of the 2010 Census and ranks as the 32nd-largest city in the U.S. As...
, Santa Fe
Santa Fe, New Mexico
Santa Fe is the capital of the U.S. state of New Mexico. It is the fourth-largest city in the state and is the seat of . Santa Fe had a population of 67,947 in the 2010 census...
, Taos
Taos, New Mexico
Taos is a town in Taos County in the north-central region of New Mexico, incorporated in 1934. As of the 2000 census, its population was 4,700. Other nearby communities include Ranchos de Taos, Cañon, Taos Canyon, Ranchitos, and El Prado. The town is close to Taos Pueblo, the Native American...
, Española
Española, New Mexico
Española also known as Espanola , is a city primarily in Rio Arriba County, New Mexico, in the United States. A portion of the central and eastern section of the city is in Santa Fe County. Española was founded in 1880 as a railroad village, incorporated as a city in 1925. The city is situated in...
, El Paso
El Paso, Texas
El Paso, is a city in and the county seat of El Paso County, Texas, United States, and lies in far West Texas. In the 2010 census, the city had a population of 649,121. It is the sixth largest city in Texas and the 19th largest city in the United States...
, and Ciudad Juarez
Ciudad Juárez
Ciudad Juárez , officially known today as Heroica Ciudad Juárez, but abbreviated Juárez and formerly known as El Paso del Norte, is a city and seat of the municipality of Juárez in the Mexican state of Chihuahua. Juárez's estimated population is 1.5 million people. The city lies on the Rio Grande...
lie within the rift.
Geology
The Rio Grande Rift represents the easternmost manifestation of widespread extension in the western U.S. during the past 35 million years. The rift consists of three major basins and many smaller basins, less than 100 km2. The three major basins (from northernmost to southernmost) are the San Luis, Espanola, and Albuquerque basins. Further south, a network of smaller basins run together. These are less topographically distinct and are typified by alternating basin and ranges. The distinction between these smaller basins and the Basin and Range Province becomes blurred in northern MexicoMexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, and is not well defined.
Basin size generally decreases to the north in the rift, where the Española covers approximately 120 km north-south and 40 km east-west, and the San Luis is roughly 120 km by 80 km. These basins may contain smaller units within them, such as the Alamosa basin within the San Luis, which is bounded by the San Juan and Tusas mountains on the west and the Sangre de Cristo
Sangre de Cristo
Sangre de Cristo can refer to either:*Sangre de Cristo Mountains, in Northern New Mexico and South-Central Colorado in the United States...
mountain range in the east. The Albuquerque basin is the largest of the three basins, spanning 160 km north-south and 86 km east-west at its widest points. It is the oldest of the three major basins, and contains 7,350 m of Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
clastic sediments deposited on Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
basement. The southernmost Albuquerque basin contains pre-rift volcanic deposits
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
, while the central and northern portions contain volcanics erupted during rifting.
In regards to the southernmost Rio Grande Rift, the rift broadens and becomes physiographically indistinguishable from the Basin and Range province.
In cross-section, the geometry of the basins within the rift are asymmetrical half-grabens
Graben
In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
, with major fault boundaries on one side and a downward hinge on the other. Which side of the basin has the major fault or the hinge alternates along the rift. The alternation between these half grabens occurs along transfer faults, which trend across the rift to connect the major basin-bounding faults and occur between basins or, in places, within basins. The Precambrian basement changes relief sharply in this area, from 8,700 m below sea level at the bottom of the Albuquerque basin to 3,300 m above sea level in the nearby Sandia Mountains
Sandia Mountains
The Sandia Mountains name posu gai hoo-oo, "where water slides down arroyo") are a mountain range located in Bernalillo and Sandoval counties, immediately to the east of the city of Albuquerque in New Mexico in the southwestern United States. The range is largely within the Cibola National...
, which flanks the Albuquerque basin to the east. Flanking mountains are generally taller along the east side of the rift (although some of this relief may be Laramide
Laramide orogeny
The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute, as is the cause. The Laramide...
in origin). The thickness of the crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
increases to the north beneath the rift, where it may be as much as 5 km thicker than it is in the south. The crustal thickness underneath the rift is on average 30–35 km thick, thinner by 10–15 km than the Colorado Plateau on the west and the Great Plains to the east.
The rift is presently nearly tectonically quiescent, but significant deformation and faulting with offsets of many kilometers were responsible for its formation starting about 35 Ma. The largest-scale manifestation of rifting involves a pure-shear rifting mechanism, in which both sides of the rift pull apart evenly and slowly, with the lower crust and upper mantle (the lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
) stretching like taffy
Taffy (candy)
Taffy is a type of chewy candy, similar to toffee. Taffy is often sold alongside bubblegum and candy. Taffy is made by stretching or pulling a sticky mass of boiled sugar, butter or vegetable oil, flavorings, and coloring until fluffy. When this process is complete, the taffy is rolled, cut into...
. This extension is associated with very low seismic velocities in the upper mantle above approximately 400 km depth associated with relatively hot mantle and low degrees of partial melting. This intrusion of the asthenosphere
Asthenosphere
The asthenosphere is the highly viscous, mechanically weak and ductilely-deforming region of the upper mantle of the Earth...
into the lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
and continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
is thought to be responsible for nearly all of the volcanism associated with the Rio Grande rift.
The sedimentary fill of the basins consists largely of alluvial fan
Alluvial fan
An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...
and mafic
Mafic
Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term is a portmanteau of the words "magnesium" and "ferric". Most mafic minerals are dark in color and the relative density is greater than 3. Common rock-forming mafic minerals include olivine,...
volcanic flows. The most alkalic lavas erupted outside the rift. The sediments that were deposited during rifting are commonly known as the Santa Fe Group. This group contains sandstones, conglomerates
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
, and volcanics. Aeolian deposits are also present in some basins.
The Rio Grande Rift is intersected in northern New Mexico by the NE-SW trending Jemez Lineament, which is defined by aligned volcanic fields and several calderas in the area, including the Valles Caldera National Preserve in the Jemez Mountains
Jemez Mountains
The Jemez Mountains are a volcanic group of mountains in New Mexico, United States. The highest point in the range is Chicoma Mountain at an elevation of 11,561 feet . The town of Los Alamos and Los Alamos National Laboratory adjoin the eastern side of the range while the town of Jemez Springs...
. The significance of the Jemez Lineament is unclear, however, it is not obviously related to the formation of the Rio Grande rift. The Colorado Plateau, to the west, includes the San Juan volcanic field
San Juan volcanic field
The San Juan volcanic field, located in southwestern Colorado, contains two distinct phases of volcanism. The earlier volcanism is Oligocene in age, and consists of largely intermediate composition lavas and breccias. A few ash flow tuffs also constitute this phase of volcanism. Later volcanism is...
in the San Juan Mountains
San Juan Mountains
The San Juan Mountains are a high and rugged mountain range in the Rocky Mountains in southwestern Colorado. The area is highly mineralized and figured in the gold and silver mining industry of early Colorado. Major towns, all old mining camps, include Creede, Lake City, Silverton, Ouray, and...
.
The youngest eruptions in the rift region are in the Valley of Fires
Carrizozo Malpais
The Carrizozo Malpais is a large lava flow on the west side of Carrizozo, New Mexico, on the northern part of the Tularosa Basin between Sierra Blanca to the southeast and the Oscura Mountains to the west....
, New Mexico and are approximately 5,400 years old. The Socorro, New Mexico
Socorro, New Mexico
Socorro is a city in Socorro County in the U.S. state of New Mexico. It stands in the Rio Grande Valley at an elevation of . The population was 9,051 at the 2010 census...
region of the central rift hosts an inflating mid-crustal sill-like magma body at a depth of 19 km that is responsible for anomalously high earthquake activity in the vicinity, including the largest rift-associated earthquakes in historic times (two events of approximately magnitude 5.8) in July and November 1906. Earth and space-based geodetic measurements indicate ongoing surface uplift above the at approximately 2 mm/year.
There is a body of magma called the Socorro Magma Body within the crust beneath Socorro, New Mexico
Socorro, New Mexico
Socorro is a city in Socorro County in the U.S. state of New Mexico. It stands in the Rio Grande Valley at an elevation of . The population was 9,051 at the 2010 census...
. The identification of this magma body came from extensive seismic data gathered in the area from the RISTRA
Ristra
thumb|right|200px|A jalapeño ristra drying.A ristra is an arrangement of drying chili pepper pods. Although their main purpose is to preserve chilis for later consumption, ristras are commonly used decoratively in chili-producing areas, especially New Mexico....
seismic program.
Geologic history
The Rio Grande rift's tectonicTectonics
Tectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
evolution is fairly complex. The fundamental change in the western margin of the North American plate from one of subduction
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
to a transform boundary
Transform fault
A transform fault or transform boundary, also known as conservative plate boundary since these faults neither create nor destroy lithosphere, is a type of fault whose relative motion is predominantly horizontal in either sinistral or dextral direction. Furthermore, transform faults end abruptly...
occurred during Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
time. The Farallon plate
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...
continued to be subducted beneath western North America for at least 100 million years during Late Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
and early Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
time. Compressional and transpressional deformation
Deformation (mechanics)
Deformation in continuum mechanics is the transformation of a body from a reference configuration to a current configuration. A configuration is a set containing the positions of all particles of the body...
incurred by the Laramide Orogeny
Laramide orogeny
The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the orogeny are in dispute, as is the cause. The Laramide...
lasted until about 40 Ma in New Mexico. This deformation may have been a result of the coupling between the subducting Farallon plate
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...
and the overlying North American plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
. Crustal thickening occurred due to Laramide compression. After the Laramide Orogeny and until 20 Ma, a major period of volcanic activity occurred throughout the southwestern United States. Injection of hot magmas weakened the lithosphere and allowed for later extension of the region.
Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
extension started about 30 million years ago (Ma). There are two phases of extension observed: late Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and middle Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
. The first period of extension produced broad, shallow basins bounded by low-angle faults. The crust might have been extended as much as 50% during this episode. Widespread magma
Magma
Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
tism in mid-Cenozoic
Cenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
tine suggests that the lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
was hot, the brittle-ductile transition was relatively shallow. In regards to the second period of extension, there is evidence that extension began earlier in the central and northern Rio Grande Rift than in the south.
It is suggested that the Colorado Plateau acts as a semi-independent microplate and one way of envisioning the creation of the Rio Grande Rift is for the simple rotation of the Colorado Plateau 1-1.5 degrees in a clock-wise direction.
See also
- Caja del Rio
- Geologic timeline of Western North AmericaGeologic timeline of Western North AmericaA timeline of significant geological events in the evolution of western North America. Dates are approximate. -External links:* http://www.geog.ucsb.edu/~joel/g148_f06/readings/geol_history/geol_history.html*...
- Pajarito PlateauPajarito PlateauThe Pajarito Plateau is a volcanic plateau in north central New Mexico, United States. The plateau, part of the Jemez Mountains, is bounded on the west by the Valles Caldera and on the east by the White Rock Canyon of the Rio Grande...
- Potrillo volcanic fieldPotrillo volcanic fieldThe Potrillo Volcanic Field is a monogenetic volcanic field located on the Rio Grande Rift, in a portion of its rift valley, in southern New Mexico, USA and northern Chihuahua, Mexico...
- Rio Grande TrailRio Grande TrailThe Rio Grande Trail is a proposed long distance trail along the Rio Grande in the U.S. state of New Mexico. The river extends over 1,800 total miles, some of which pass though the heart of New Mexico. It is the state's primary drainage feature and most valuable natural and cultural resource...