Tehuantepec Ridge

Approximate surface projection on Pacific Ocean of the Tehuantepec Ridge (orange). To its north-west off the coast of Mexico is the O’Gorman fracture zone (also orange). It is subducting under the Middle America Trench (white). Click to expand map to obtain interactive details.^[1]

The Tehuantepec Ridge (Tehuantepec Fracture Zone, Tehuntepec Ridge)^[2] is a linear undersea ridge located off the west coast of Mexico in the Pacific Ocean. It is the remnant of an old fracture zone, and not a tectonic spreading center ridge (see mid-ocean ridge). It extends from the eastern end of the Clipperton Fracture Zone northeastward toward Mexico into Chiapas and El Chichón^[3] until it is subducted into the Middle America Trench. It lies within the tectonic Cocos Plate, separating the lower and older seafloor of the Guatemala Basin which lies southeast of the ridge from higher and younger seafloor which lies to its north-west.

Current research indicates that the ridge was formed as a fracture zone and transform fault along the East Pacific Rise. As a result of a change in the motion of the Pacific Plate about 13 million years ago, there was also a change in the orientation of the East Pacific Rise, which in turn reoriented the fracture zone, creating the current alignment that is today's Clipperton Fracture Zone. The Tehuantepec Ridge preserves the previous orientation. To its north the O’Gorman Fracture Zone has a similar orientation.

Some researchers have hypothesized that the subducted portion of the Tehuantepec Ridge under Mexico is responsible for the existence of El Chichón volcano as well as the other volcanoes of what is called the Chiapanecan Volcanic Arc. Studies of the 1982 eruption of El Chichón indicated its erupted output was unusual compared to other volcanoes in the Trans-Mexican Volcanic Belt which lies well to the northwest. The anomaly is thought to result from the distinctive composition of the rocks which comprise the Tehuantepec Ridge.^[4]^[5]

12°21′40.8″N 97°46′21.5″W / 12.361333°N 97.772639°W / 12.361333; -97.772639^[2]

References

^ General citations for named fracture zones are at page Wikipedia:Map data/Fracture zone and specific citations are in interactive detail.
^ ^a ^b "Marine Gazetteer:Tehuantepec Fracture Zone". Retrieved 11 January 2024.
^ Manea, Marina; Manea, Vlad C. (2008-08-20). "On the origin of El Chichón volcano and subduction of Tehuantepec Ridge: A geodynamical perspective". Journal of Volcanology and Geothermal Research. 175 (4): 459–471. Bibcode:2008JVGR..175..459M. doi:10.1016/j.jvolgeores.2008.02.028.
^ Vlad C. Manea and Marina Manea, 2005, THE ORIGIN OF MODERN CHIAPANECAN VOLCANIC ARC IN SOUTHERN MEXICO INFERRED FROM THERMAL MODELS, http://www.geo.mtu.edu/~raman/papers2/Manea_Chiapas_2005.pdf 2.2mb
^ Rose, William Ingersoll (2006-01-01). Volcanic Hazards in Central America. Geological Society of America. ISBN 978-0-8137-2412-6.