Chuska mountains

The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km (50 by 10 miles), and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of about 2700 meters (about 8900 feet), and relatively subdued topography. The highest point is Roof Butte (36°28' N, 109°6' W) at 2982 meters (9783 feet), near the northern end of the range in Arizona. Other high points include the satellite Beautiful Mountain at 2861 meters (9388 feet) and Lukachukai Mountains at 2885 meters (9466 feet), both also near the northern end, and Matthews Peak at 2911 meters (9550 feet). The San Juan Basin borders the Chuskas on the east, and typical elevations in nearby parts of that basin are near 1800 meters (about 5900 feet). The eastern escarpment of the mountains is marked by slumps and landslides that extend out onto the western margin of the San Juan Basin. To the north, the Chuskas are separated from the Carrizo Mountains by Red Rock Valley.
Enlarge picture
Satellite image of northeastern Arizona and northwestern New Mexico, including the Four Corners Monument (FC). Some higher elevations have a dust of snow. Labeled natural features are the Chuska Mountains (CM), the Carrizo Mountains (C), Monument Valley Navajo Tribal Park (MV), Black Mesa (B), Canyon de Chelly National Monument (CdC), and the Defiance Uplift (D). Labeled towns are Farmington, New Mexico (F), Gallup, New Mexico (G), Window Rock, Arizona (WR), and Kayenta, Arizona (K).


Much of the range is Navajo Nation Forest, and ponderosa pine, spruce, and fir are among the important tree varieties. Trees there were cut and transported more than 75 km (about 50 miles) to the east to construct pueblos in Chaco Culture National Historical Park in the San Juan Basin as early as 974 A.D. Logging in the mountains continues today, with attendant environmental controversies.

The forests of the Chuska Mountains and of the Defiance Uplift receive higher rainfall than the surrounding lowlands, and these highlands typically generate more than half the surface water of the Navajo Nation. Canyons of Canyon de Chelly National Monument were cut by streams with headwaters in the Chuskas.

The Chuska Mountains are sparsely populated. Nearby settlements are small, and they include Crystal, New Mexico, and Lukachukai, Arizona, to the west and Toadlena, New Mexico, to the east. Trading posts at Crystal and at Two Grey Hills (about 10 km east of Toadlena), are associated with distinctive patterns used in Navajo rugs. A paved road, New Mexico Highway 134, crosses the range through Narbona Pass. Narbona Pass was formerly named Washington Pass, after Colonel John M. Washington, who commanded a military expedition against the Navajo. Narbona was a Navajo headman killed in an encounter with Washington's troops in 1849.

Geology

The Chuska Mountains and the Defiance Uplift immediately to the southwest form one of the prominent uplifted highs of the Colorado Plateau. The uplifted region is separated from the San Juan Basin to the east by the Defiance and associated monoclines. Relative uplift, basin subsidence, and monocline formation began in the early stages of the Laramide orogeny about 75 to 80 million years ago. Although the Chuska Mountains can be considered part of the Defiance Uplift, they stand relatively higher. They are capped by an erosional remnant of Chuska Sandstone, a unit locally more than 500 meters thick. The flat-lying Chuska Sandstone rests unconformably on Mesozoic rocks deformed in the Defiance monocline. Biotite in layers of altered ash within the Chuska Sandstone has yielded radiometric ages of 35 and 33 million years by argon-argon dating. The Chuska Sandstone is formed of sand dune deposits, and it appears to be a remnant of a huge Oligocene sand sea, the Chuska erg. The erg hypothesis is consistent with major exhumation of the central Colorado Plateau in the late Oligocene and early Miocene (e.g., from about 26 to 16 million years ago). If so, then major uplift of the central Colorado Plateau may postdate the Laramide orogeny.

Minette of the Navajo Volcanic Field intruded and was extruded through the Chuska Sandstone. Minette makes up the two highest points, Roof Butte and Matthews Mountain. A maar complex, containing pyroclastic and extrusive minette, is exposed along New Mexico Highway 134 in Narbona Pass. Argon-argon dating of four minette samples at Narbona Pass yielded consistent ages of 25 million years. Very little oil has been produced in Arizona, and much of that production has come from a minette sill, the reservoir rock of the Dineh-bi-Keyah field in the northwestern Chuska Mountains near Roof Butte. The sill is intruded into lower Pennsylvanian sedimentary rocks. The producing rock is both porous and fractured, and it is characterized by relatively large poikilitic sanidine grains with inclusions of diopsidic augite and biotite: potassium-argon dating of the biotite yielded 25.7 million years. This pulse of magmatism at about 25 million years may have been accompanied by uplift of the Defiance-Chuska high in addition to the uplift during the Laramide orogeny.

Helium-rich gas has been extracted from Devonian strata in the Dineh-bi-Keyah field. Additional economic resources have included uranium, mined from some of the Mesozoic strata, particularly from the Morrison Formation in the Lukachukai Mountains at the northwest end of the Chuska Mountains.

(Geologic investigations in the Navajo Nation can be undertaken only with a permit from the Navajo Nation Minerals Department.)

References

  • Spencer G. Lucas, Steven C. Semken, William R. Berglof, and Dana S. Ulmer-Scholle (editors), Geology of the Zuni Plateau, New Mexico Geological Society Fifty-fourth Annual Field Conference, 424 p., 2003.
  • Steven M. Cather, Lisa Peters, Nelia W. Dunbar, and William C. McIntosh, Genetic Stratigraphy, Provenance, and New Age Constraints for the Chuska Sandstone (Upper Eocene-Lower Oligocene), New Mexico-Arizona. in Lucas et al., cited above, p. 397-412.
  • Steven M. Cather, The Chuska erg: Paleogeomorphic and Paleoclimatic implications of an Oligocene sand sea on the Colorado Plateau, Four Corners Geological Society News Letter, February 2007 (accessed May, 2007), http://www.fourcornersgeologicalsociety.org/
  • Patrick Pynes, Chuska Mountains and Defiance Plateau, Navajo Nation. Part of the CP-LUHNA Web pages of Grahame, John D. and Thomas D. Sisk, ed., Canyons, cultures and environmental change: An introduction to the land-use history of the Colorado Plateau, 2002. (accessed July, 2006), http://www.cpluhna.nau.edu/Places/chuska_mtns.htm
  • Nathan B. English, Julio L. Betancourt, Jeffrey S. Dean, and Jay Quade, Strontium isotopes reveal distant sources of architectural timber in Chaco Canyon, New Mexico. Proceedings National Academy of Sciences USA 98, 11891-11896, 2001.
Coordinates:
The Colorado Plateau, also called the Colorado Plateaus Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States.
..... Click the link for more information.
Navajo Nation (Diné in Navajo language) encompasses all things important to the Navajo. The land, kinship, language, religion and the right to govern themselves. The Navajo Homeland covers about 26,000 square miles (70,000 square kilometres, 17 million acres) of land,
..... Click the link for more information.
Arizona State Symbols
Living Symbols
 -Animal Ringtail Cat
 -Bird Cactus Wren
 -Butterfly Two-Tailed Swallowtail
 -Fish Apache Trout
 -Flower Saguaro Blossom
 -Furbearer Ringtail Cat
..... Click the link for more information.
State of New Mexico

Flag of New Mexico Seal
Nickname(s): Land of Enchantment / Tierra del Encanto
Motto(s): Crescit eundo

Capital Santa Fe
Largest city Albuquerque
Largest metro area
..... Click the link for more information.
The Carrizo Mountains (36°50' N, 109°7'W) are a small range 15 to 20 km (9 to 12 miles) in diameter located on the Colorado Plateau in northeastern Arizona. The range is about 20 km southwest of the Four Corners.
..... Click the link for more information.
Location San Juan County, New Mexico, USA
Nearest city Farmington, New Mexico
Coordinates
Area 33,974.29 acres
(137.
..... Click the link for more information.
Navajo Nation (Diné in Navajo language) encompasses all things important to the Navajo. The land, kinship, language, religion and the right to govern themselves. The Navajo Homeland covers about 26,000 square miles (70,000 square kilometres, 17 million acres) of land,
..... Click the link for more information.
Location Arizona, USA
Nearest city Chinle, Arizona
Coordinates
Area 83,840 acres (339.28 km²)
Established April 1, 1931
Total visitation 881,783 (in 2004)
Governing body
..... Click the link for more information.
The Colorado Plateau, also called the Colorado Plateaus Province, is a physiographic region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States.
..... Click the link for more information.
fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i.e. permanent) deformation. Synsedimentary folds are those due to slumping of material before deformation.
..... Click the link for more information.
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.
..... Click the link for more information.
The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' (making the modern era the 'Tertiary').
..... Click the link for more information.
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K(Mg, Fe)3AlSi3O10(F, OH)2.
..... Click the link for more information.
Argon-argon (or 40Ar/39Ar) dating is a radiometric dating technique similar to potassium-argon (K-Ar) dating. In this technique, the decay of 40K to 40
..... Click the link for more information.
dune is a hill of sand built by eolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the wind.
..... Click the link for more information.
The Oligocene epoch is a geologic period that extends from about 33.9 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
..... Click the link for more information.
erg (also sand sea or dune sea) is a large, relatively flat area of desert covered with wind-swept sand with little to no vegetation cover.[1] The term takes its name from the Arabic word erg (
..... Click the link for more information.
The Oligocene epoch is a geologic period that extends from about 33.9 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
..... Click the link for more information.
The Miocene Epoch is a period of time that extends from about 23.03 to 5.332 million years before the present. As with other older geologic periods, the rock beds that define the start and end are well identified but the exact dates of the start and end of the period are uncertain.
..... Click the link for more information.
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.
..... Click the link for more information.
Minette is a variety of igneous rock. More specifically, minette is a type of lamprophyre with phenocrysts of biotite, and with or without phenocrysts of hornblende, augite with a high diopside content, and olivine.
..... Click the link for more information.
maar is a broad, low relief crater that is caused by a phreatic eruption or explosion caused by groundwater contact with hot lava or magma. The maar typically fills with water to form a relatively shallow crater lake.
..... Click the link for more information.
Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire, and κλαστός, meaning broken) are clastic rocks composed solely or primarily of volcanic materials.
..... Click the link for more information.
Argon-argon (or 40Ar/39Ar) dating is a radiometric dating technique similar to potassium-argon (K-Ar) dating. In this technique, the decay of 40K to 40
..... Click the link for more information.
Pennsylvanian is an epoch of the Carboniferous period lasting from roughly 325 Ma to 299 Ma (million years ago). As with most other geologic periods, the rock beds that define the period are well identified, but the exact date of the start and end are uncertain by a few million
..... Click the link for more information.
Poikilitic texture refers to crystals, typically phenocrysts, in an igneous rock which contain small grains of other minerals. The texture is most easily observed in petrographic thin sections.
..... Click the link for more information.
Sanidine is the high temperature form of potassium feldspar (K,Na)(Si,Al)4O8.[1] Sanidine most typically occurs in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system.
..... Click the link for more information.
Augite is a mineral described chemically as (Ca,Mg,Fe)SiO3 or calcium magnesium iron silicate. The crystals are monoclinic and prismatic. Augite has two prominent prismatic cleavages, meeting at angles near 90°.
..... Click the link for more information.
Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K(Mg, Fe)3AlSi3O10(F, OH)2.
..... Click the link for more information.
Potassium-argon or K-Ar dating is a geochronological method used in many geoscience disciplines. It is based on measuring the products of the radioactive decay of potassium (K), which is a common element found in materials such as micas, clay minerals, tephra and evaporites.
..... Click the link for more information.


This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.