Introduction
Mountain range in New Mexico, United States
Jemez MountainsChicoma Mountain, the highest peak of the JemezHighest pointPeakChicoma MountainElevation3,524 m (11,562 ft) NAVD 88Coordinates36°00′26″N 106°23′04″W / 36.00722°N 106.38444°W / 36.00722; -106.38444GeographyJemez Mountains
CountryUnited StatesStateNew MexicoTopo mapUSGS Polvadera Peak (1977)
The Jemez Mountains (/ˈheɪmɛz/, Tewa: Tsąmpiye'ip'įn, Navajo: Dził Łizhinii) are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States.
Numerous Puebloan Indian tribes have lived in the Jemez Mountains region for centuries before the Spanish arrived in New Mexico. The Pueblo Nations of this region are the Towa-speaking Jemez people, after whom the mountain range is named, and the Keres-speaking Zia People. Pueblos in the Jemez Mountains of New Mexico consisted of compact multistoried buildings which enclosed small plazas. Most of their several hundred rooms were probably occupied by single families, but some were storerooms.
The Jemez Mountains include climates varying from desert at the lowest elevations to sub-arctic conditions at the highest elevations. A significant diversity of climate and vegetation is linked to gradients in elevation and the region's topographical features. The highest point in the range is Chicoma Mountain (also spelled as Tschicoma or Tchicoma) at an elevation of 11,561 feet (3,524 meters). The town of Los Alamos and the Los Alamos National Laboratory adjoin the eastern side of the range while the town of Jemez Springs is to the west. Pajarito Mountain Ski Area is the only ski area in the Jemez. New Mexico State Highway 4 is the primary road that provides vehicular access to locations in the Jemez Mountains.
Geology
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The Jemez Mountains lie in north-central New Mexico, to the north of the Albuquerque Basin in the Rio Grande rift, and span altitudes from 1,590 meters at the Rio Grande to 3,526 meters at the peak of Tschicoma Peak. This geological demarcation encompasses approximately 543,522 hectares, according to Smith et al.'s 1976 study. They are a classic example of intracontinental volcanism and consist of a broadly circular ridge surrounding the Valles Caldera. The latter is the type location for resurgent caldera eruptions.
The mountains lie on the intersection of the western margin of the Rio Grande rift and the Jemez Lineament. Here magma produced from the fertile rock of an ancient subduction zone has repeatedly found its way to the surface along faults produced by rifting. This has produced a long-lived volcanic field, with the earliest eruptions beginning at least 13 million years ago and continuing almost to the present day. The most recent known eruption is the obsidian of the Banco Bonito flow, dated to 68.3 ± 1.5 thousand years before the present.
Most of the volume of the range is composed of pre-caldera basalts, andesites, and dacites of the Keres Group and Polvadera Group, but there are extensive outflow sheets of the Bandelier Tuff and young rhyolites associated with caldera resurgence, all assigned to the Tewa Group.Guadelupita Mesa in the southwestern JemezThe two most recent caldera-forming eruptions, dated to about 1.62 million and 1.256 million years ago, produced massive ignimbrite deposits known as the Otowi and Tshirege members, respectively, of the Bandelier Tuff. Much of the material in these deposits now forms the Pajarito Plateau, a scenic region of canyons and mesas on which Los Alamos is situated. Redondo Peak, the second-highest summit in the range at 11,254 ft (3431 m), is a resurgent dome in the middle of the Valles Caldera, which also contains several smaller volcanos. In the Jemez Mountains, the Quaternary volcanic field, encompasses the Valles caldera and the connected Bandelier Tuff. The caldera is segregated by these structures and its rim into multiple lush grass valleys (valles in Spanish, hence the name).
The western part of the Valles Caldera is underlain by a seismic low-velocity zone with an area of 10 by 14 kilometers (6.2 by 8.7 mi) and extending to depths of 5 to 15.5 kilometers (3.1 to 9.6 mi). This zone consists of at least 10% molten rock and represents a new pulse of magmatic activity. This is monitored by the Los Alamos Seismic Network, which has detected no unusual volcano-seismic activity since it was installed in the 1970s.