Trans-Mexican Volcanic Belt

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For other uses, see Sierra Nevada (disambiguation).
Trans-Mexican Volcanic Belt
Iztaccíhuatl, Popocatépetl, Matlalcueitl (Malinche), Nauhcampatépetl (Cofre de Perote, most distant), Citlaltépetl (Pico de Orizaba), Sierra Negra
TypeVolcanic arc[1]
OverliesSierra Madre Occidental[1][2]
Area160,000 kilometres (99,000 mi)2 [1]
ThicknessEast of 101°W 50-55 km[1] West of 101°W 35-40 km
Central Mexico
CountryMexico
Extent1,000 kilometres (620 mi) [3]

The Trans-Mexican Volcanic Belt (Spanish: Eje Volcánico Transversal), also known as the Transvolcanic Belt and locally as the Sierra Nevada (Snowy Mountain Range),[4] is an active volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and during clear weather, they are visible to a large percentage of those who live on the many high plateaus from which these volcanoes rise.

History

The Trans-Mexican Volcanic Belt spans across Central-Southern Mexico from the Pacific Ocean to the Gulf of Mexico between 18°30'N and 21°30'N, resting on the southern edge of the North American Plate.[1][5] This approximately 1000 kilometer long, 90–230 km broad structure is an east–west, active, continental

plates beneath the North American Plate along the northern end of the Middle America Trench formed the Trans-Mexican Volcanic Belt.[6][7]
The Trans-Mexican Volcanic Belt is a unique volcanic belt; it is not parallel to the Middle American Trench, and many of the main
calderas.[3]

Geologic framework

Nevado de Colima, Parícutin, Popocatépetl, and Pico de Orizaba
.

Prior to the formation of the Trans-Mexican Volcanic Belt, an older, but related volcanic belt, the

Laramide deformation, subduction related volcanism formed the Sierra Madre Occidental silic volcanic arc at a paleo-subduction zone off the coast of Baja California, before the peninsula rifted away.[5][9][10]
From the
siliclastic turbidites. Assemblage of these basement rocks results with a thickness of 50–55 km east of 101°W and 35–40 km west of 101°W.[1][8]

Plate evolution

The subducting plates originated from the breakup of the

calc-alkaline rocks volumetrically occupy a majority of the Trans-Mexican Volcanic Belt but smaller volumes of intraplate-like lavas, potassium rich rocks, and adakites are associated with the area.[3] Middle Miocene adakitic (more felsic) rocks are found furthest from the trench and along the volcanic front of the central Trans-Mexican Volcanic Belt during the Pliocene-Quaternary. It has been suggested that slab melting contributed to the adakitic imprint on the Trans-Mexican Volcanic Belt, prompted by the prolonged flat subduction of the Cocos Plate.[3]

Belt evolution

Formation

slab rollback
sending the volcanic arc trenchward to the present day position
  1. From the early to mid Miocene ~20 to 8 Ma, the initial Trans-Mexican Volcanic Belt volcanic arc consisted of intermediate effusive volcanism, producing
    Michoacan (longitude 102°W) to the Palma Sola area (longitude 98°30'). The plate boundary geometry and sub-horizontal subducting slab's thermal structure are the controlling factors for initial arc volcanism.[9] Magmatism migrated away from the trench, moving northeast towards the Gulf of Mexico—giving the arc its characteristic E-W orientation, the inland push of the arc showed progressively drier melting, and eventually slab melting began to occur—suggesting flattening of the subducted slab.[1][5] The oldest rocks of this age may be exposed near the modern volcanic front, in Central Mexico.[14]
  2. A Late Miocene ~11 Ma eastward traveling pulse of mafic volcanism swept across the whole of Central Mexico, north of the previously formed arc, ending ~ 3 Ma. The onset of the mafic lavas indicates lateral propagation of slab tear, prompted by the end of subduction beneath Baja California, allowing the influx of asthenosphere into the mantle wedge.[12] This volcanism created basaltic plateaus through fissures, or less commonly, small shield volcanoes and lava cones, with diminishing lava volume eastward.[1][13]
  3. West of 103°W, silicic volcanism between 7.5 and 3.0 Ma became bimodal (mafic-silicic) in the early Pliocene, creating large dome complexes and ignimbrites, and marked the beginning of trenchward migration of volcanism. East of 101°W dome complexes, lava flows, and large calderas that produced significant quantities of ignimbrites (>50 km3) of dacitic to rhyolitic composition can be found dating between 7.5 and 6 Ma. There is an absence of silicic volcanism between these regions during the whole Trans-Mexican Volcanic Belt history. Since the late Miocene, silicic volcanism migrated trenchward over 200 km in the eastern sector (east of 101°W) and 100 km in the western sector (West of 103°W).[1][5][13][14]
  4. Since the late Pliocene, the style and composition of volcanism in the Trans-Mexican Volcanic Belt became more diverse. In several areas, volumetrically dominant calc-alkaline rocks are associated with modest volumes of intraplate-like lavas or other potassium rich rocks, accompanied by Quaternary rhyolitic peralkaline rocks. This modern arc consists of a frontal belt dominated by flux and slab melting and a rear belt characterized by the differentiated rocks stated previously.[1][3] Absent since ~9 Ma, stratovolcanoes began to be created in the last 1 Ma ~100 km behind the volcanic front in the Western Sector, oriented West - Northwest and East - Southeast. In the eastern sector, all stratovolcanoes are found within the volcanic front. One exception to the location of these stratovolcanoes is the Colima volcanic complex, which is positioned south of the southern tip of the Cocos and Rivera slab tear and is the largest volcanic edifice in the Trans-Mexican Volcanic Belt.[1] In addition to stratovolcanoes, monogenetic volcanic fields are also characteristic for this episode, the most prominent being the Michoacán–Guanajuato volcanic field.

Cause of flat slab subduction

oceanic plate from entering the mantle.[1][11]

Geography

Region

From the west, the Trans-Mexican Volcanic Belt runs from

Hidalgo, the Distrito Federal, northern Morelos, Puebla, and Tlaxcala, to central Veracruz
.

The Mexican Plateau lies to the north, bounded by the Sierra Madre Occidental to the west and Sierra Madre Oriental to the east. The Cofre de Perote and Pico de Orizaba volcanoes, in Puebla and Veracruz, mark the meeting of the Trans-Mexican Volcanic Belt with the Sierra Madre Oriental. To the south, the basin of the Balsas River lies between the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur. This area is also a distinct physiographic province of the larger Sierra Madre System physiographic division.[4]

The Sierra de Ajusco-Chichinauhtzin also forms part of the Belt.[15]

Peaks

Pico de Orizaba

The highest point, also the highest point in Mexico, is Pico de Orizaba (5,636 metres (18,491 ft)) also known as Citlaltépetl, located at 19°01′N 97°16′W / 19.017°N 97.267°W / 19.017; -97.267. This, and several of the other high peaks, are active or dormant volcanoes.

Other notable volcanoes in the range include (from west to east)

Matlalcueitl (4,461 metres (14,636 ft)) Cofre de Perote (4,282 metres (14,049 ft)) and Sierra Negra, a companion of the Pico de Orizaba (4,580 metres (15,030 ft)).[4]

Ecology

The mountains are home to the

Mesoamerican pine-oak forests sub-ecoregions
.

The Trans-Mexican Volcanic Belt has many endemic species, including the Transvolcanic jay (Aphelocoma ultramarina).[4]

Volcanic ash make soils in the region very fertile, which (especially coupled with elevation making tropical climate milder) has led to high human population densities in the belt that now sometimes strain the environment.

See also

References

  1. ^
    doi:10.1016/j.tecto.2011.09.018
    .
  2. ^
    doi:10.1029/91jb00428
    .
  3. ^
    doi:10.1016/j.tecto.2012.12.039
    .
  4. ^
    ISBN 978-970-26-0357-3
    .
  5. ^ a b c d e f Ferrari, Luca. "The Geochemical Puzzle of the Trans-Mexican Volcanic Belt: Mantle Plume, Continental Rifting, or Mantle Perturbation Induced by Subduction?". www.MantlePlumes.org.
  6. ^
    doi:10.1016/s0040-1951(02)00511-5
    .
  7. ^ Garcia-Palomo, A.; Macias, J; Tolson, G; Valdez, G; Mora, J (2002). "Volcanic stratigraphy and geological evolution of the Apan region, east-central sector of the Trans-Mexican Volcanic Belt". Geofísica Internacional. 41 (2): 133–150.
  8. ^ a b Guzman, Eduardo; Zoltan, Cserna (1963). "Tectonic History of Mexico". AAPG Special Volumes. 151: 113–129.
  9. ^
    doi:10.1130/0091-7613(1999)027<0303:stpoca>2.3.co;2
    .
  10. doi:10.1186/bf03351651
    .
  11. ^
    doi:10.1029/2008GL035127
    .
  12. ^
    doi:10.1130/g19887.1
    .
  13. ^
    doi:10.1130/0091-7613(2001)029<0507:gooibt>2.0.co;2
    .
  14. ^
    doi:10.1130/2007.2422(05)
    .
  15. ^ Jimenez Gonzalez, Victor Manuel (2014). Guía de Viaje del Distrito Federal (DF) [Federal District Travel Guide (DF)] (in Spanish). Solaris Comunicación. p. 39.

External links

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