The Jemez Lineament is a chain of late

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

volcanic field A volcanic field is an area of Earth's Earth's crust, crust that is prone to localized volcano, volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters ...

s, long, reaching from the Springerville and White Mountains volcanic fields in East-Central

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

to the Raton-Clayton volcanic field in Northeastern

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

. The lineament was long interpreted as a hotspot trace (Raton hotspot) due to its resemblance in length and direction to the Yellowstone hot spot trace, but there is no systematic progression in age along the trace and it is now interpreted as a hydrous subduction zone scar. This formed about 1.7 billion years ago, when

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...

was subducting under what was then the southern edge of North America. The arrival of a large

island arc Island arcs are long archipelago, chains of active volcanoes with intense earthquake, seismic activity found along convergent boundary, convergent plate tectonics, tectonic plate boundaries. Most island arcs originate on oceanic crust and have re ...

in the subduction zone shifted subduction further south, leaving remnants of oceanic crust at the top of the Earth's mantle along the former subduction zone. These are rich in hydrous minerals that lower the melting temperature of the rock containing them. This hydrous subduction scar now separates

basement A basement is any Storey, floor of a building that is not above the grade plane. Especially in residential buildings, it often is used as a utility space for a building, where such items as the Furnace (house heating), furnace, water heating, ...

rock of the Yavapai- Mazatzal transition zone from the Mazaztl Province proper.

Volcanic fields

The Jemez Lineament consists of the San Carlos volcanic field, Springerville volcanic field, Red Hill volcanic field, Zuni-Bandera volcanic field, Mount Taylor volcanic field, Jemez volcanic field and possibly the Ocate volcanic field, Raton-Clayton volcanic field, and Mesa de Maya. These are all young (

) volcanic fields, showing some progression in age from southeast to northwest (across the Lineament) but no systematic progression in age along the Lineament. The total surface area of volcanic products of the Jemez Lineament volcanic fields is . The total erupted volume is about . The Jemez volcanic field, located at the intersection of the Rio Grande Rift with the lineament, has produced three times the volume of eruption as the other fields in the lineament combined. The trace of the lineament changes slightly across the Rio Grande rift. To the west of the rift, the lineament follows the southeastern margin of the Colorado Plateau. East of the rift, the lineament cuts across the High Plains. The volcanism within the lineament is highly varied, including the large

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

eruptions of the Jemez volcanic field, the

stratovolcano A stratovolcano, also known as a composite volcano, is a typically conical volcano built up by many alternating layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with ...

es of Mount Taylor and Sierra Grande, and the monogenetic volcanism of most of the volcanic fields. Almost every kind of volcanic landform can be found within the lineament. The chemical compositions of the magmas are mostly

alkaline In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...

to slightly alkaline, with calc-alkaline and tholeiitic magma restricted to the central part of the Lineament (Mount Taylor, Jemez, and Taos fields).

Origin

The fields within the lineament vary considerably in geometry perpendicular to the trend of the lineament, showing that the lineament does not consist of a single fault or other structure. It is interpreted instead as a hydrous subduction zone scar marking the southern boundary of the pre-1700 Ma Yavapai basement. Seismic imaging shows both north- and south- dipping reflections that converge at the crust-mantle boundary. There is also a Pb-isotopic boundary coincident with the Lineament. Geophysical studies have identified a low-velocity upper mantle zone coincident with the lineament. The lineament is a zone of persistent crustal weakness.

Economic resources

The Jemez Lineament was first identified by E.B. Mayo in 1958 as a guide for mineral exploration. Mineral resources along the Lineament include

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

fields at either end of the lineament,

perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the Hydrate, hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an indu ...

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...

, and construction materials. Gold and silver were mined from epithermal deposits in the southeastern Jemez Mountains. The carbon dioxide fields, near the Springerville and Raton-Clayton volcanic fields, are unusual in containing a very large volume of carbon dioxide showing

stable isotope Stable nuclides are Isotope, isotopes of a chemical element whose Nucleon, nucleons are in a configuration that does not permit them the surplus energy required to produce a radioactive emission. The Atomic nucleus, nuclei of such isotopes are no ...

ratios indicating an origin in the Earth's mantle. Geologists have puzzled over how so much carbon dioxide could be derived from the mantle. However, a volume of silica-poor magma similar to the volume of the associated volcanic fields, if initially saturated with carbon dioxide, would produce roughly the required amount of carbon dioxide if completely degassed.

Uranium Uranium is a chemical element; it has chemical symbol, symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Ura ...

deposits in the Grants, New Mexico area underlie the Mount Taylor volcanic field, but there is no clear connection.

References

External links

*
Diagram of the Jemez Lineament and the Rio Grande Rift in relationship to the Valles Caldera (modified from Goff et al., 1981).
from vcnpearthsystems.nmepscor.net accessed August 19, 2016. {{coord missing, New Mexico Volcanism of New Mexico Jemez Mountains Volcanoes of New Mexico