29°20′N 114°30′W / 29.33°N 114.5°W / 29.33; -114.5[1] Jaraguay volcanic field is a volcanic field in northern Baja California, Mexico.[1]

Jaraguay volcanic field is part of a chain of volcanic fields that formed on the Baja California peninsula after subduction of the Pacific plate beneath it ceased. Starting from the north they are San Quintín, Jaraguay, San Borja, Santa Clara, San Ignacio–San José de Gracia, Santa Rosalía and La Purísima (volcano) volcanic fields.[2]

The field consists of cinder cones and lava flows.[1] The lavas cover a surface area of 2,200 square kilometres (850 sq mi) and tend to have thicknesses 5–35 metres (16–115 ft). Many of these were erupted from fissures with no clear vents.[3] Cinder cones have average heights of 720 metres (2,360 ft) above basis. There is some geographical differentiation with the largest cones found on the western side and the cones concentrated on the easternmost edge.[4] A flat lava plateau also makes up the field. Approximately 214 vents were counted in 2013. Many of these vents are elongated in north-south direction, with a slight NNW-SSE slant.[5]

Rocks erupted in the field range from magnesium-rich[5] basalt to basaltic andesite.[1] These magnesium rich lavas have been named "bajaites".[6] Late Miocene adakites are also found in Jaraguay.[2] These melts probably form from dehydration melting of the mantle modified by the previous subduction of the Farallon plate;[3] another older theory attributed their formation to the attempted subduction of a spreading ridge.[7] The basement of the field is formed by Mesozoic sedimentary sequences with Cretaceous intrusions and Tertiary volcanic rocks.[3]

Activity may be of Holocene age; some flows appear to be more recent than lava flows from San Quintín Volcanic Field which overlie 5,000-6,000-year-old deposits.[1] Other than that, potassium-argon dating indicates effusive activity between 20 and 14 million years ago with a peak between 12.2 and 3.9 million years ago.[5]

References

  1. 1 2 3 4 5 "Jaraguay Volcanic Field". Global Volcanism Program. Smithsonian Institution.
  2. 1 2 Negrete-Aranda, Raquel; Cañón-Tapia, Edgardo (April 2008). "Post-subduction volcanism in the Baja California Peninsula, Mexico: The effects of tectonic reconfiguration in volcanic systems". Lithos. 102 (1–2): 392–414. doi:10.1016/j.lithos.2007.08.013.
  3. 1 2 3 Pallares, Carlos; Bellon, Hervé; Benoit, Mathieu; Maury, René C.; Aguillón-Robles, Alfredo; Calmus, Thierry; Cotten, Joseph (September 2008). "Temporal geochemical evolution of Neogene volcanism in northern Baja California (27°–30° N): Insights on the origin of post-subduction magnesian andesites". Lithos. 105 (1–2): 162–180. doi:10.1016/j.lithos.2008.03.004.
  4. ↑ Negrete-Aranda, R.; Canon-Tapia, E. "Morphological Study of Jaraguay and San Borja Volcanic Fields, Baja California, Mexico". The SAO/NASA Astrophysics Data System. American Geophysical Union, Fall Meeting 2005. Bibcode:2005AGUFM.V21D0641N.
  5. 1 2 3 Germa, Aurélie; Connor, Laura J.; Cañon-Tapia, Edgardo; Le Corvec, Nicolas (21 November 2013). "Tectonic and magmatic controls on the location of post-subduction monogenetic volcanoes in Baja California, Mexico, revealed through spatial analysis of eruptive vents". Bulletin of Volcanology. 75 (12). doi:10.1007/s00445-013-0782-6.
  6. ↑ Bellon, Hervé; Aguillón-Robles, Alfredo; Calmus, Thierry; Maury, René C.; Bourgois, Jacques; Cotten, Joseph (April 2006). "La Purísima volcanic field, Baja California Sur (Mexico): Miocene to Quaternary volcanism related to subduction and opening of an asthenospheric window". Journal of Volcanology and Geothermal Research. 152 (3–4): 253–272. doi:10.1016/j.jvolgeores.2005.10.005.
  7. ↑ Scott E. Johnson (2003). Tectonic Evolution of Northwestern México and the Southwestern USA. Geological Society of America. p. 34. ISBN 978-0-8137-2374-7.
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