Cocos Plate
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robot Adding: [[ca:Placa de Cocos]]
[[Image:Plates tect2 en.svg|thumb|right|300px|{{legend|#AFBAD6|The Cocos plate, shown in gray-blue, off the Pacific coast of Central America|border=#000 solid 1px}}]]
The '''Cocos Plate''' is an oceanic [[tectonic plate]] beneath the [[Pacific Ocean]] off the west coast of [[Central America]], named for [[Cocos Island]], which rides upon it.
The Cocos Plate is created by [[sea floor spreading]] along the [[East Pacific Rise]] and the [[Cocos Ridge]], specifically in a complicated area geologists call the Cocos-Nazca spreading system. From the rise the plate is pushed eastward and pushed or dragged (perhaps both) under the less dense overriding [[Caribbean Plate]], in the process called [[subduction]]. The subducted leading edge heats up and adds its water to the mantle above it. In the mantle layer called the [[asthenosphere]], mantle rock melts to make [[magma]], trapping [[superheated water]] under great pressure. As a result, to the northeast of the subducting edge lies the continuous arc of [[volcano]]s stretching from [[Costa Rica]] to [[Guatemala]] and a belt of earthquakes that extends farther north, into [[Mexico]].
[[Image:Cocos-Caribbean.jpg|thumb|left|300px|Detail of the Cocos and Caribbean plates]]
The northern boundary of the Cocos Plate is the [[Middle America Trench]]. The eastern boundary is a [[transform fault]], the [[Panama Fracture Zone]]. The southern boundary is a [[mid-oceanic ridge]], the [[Galapagos Rise]].<ref>[http://adsabs.harvard.edu/abs/1970MarGR...1...85G Paul J. Grim, "Connection of the Panama fracture zone with the Galapagos rift zone, eastern tropical Pacific"].</ref> The western boundary is another mid-ocean ridge, the [[East Pacific Rise]].
The Cocos and Nazca Plates are the remnants of the former [[Farallon Plate]], which broke up about 23 million years ago. A [[Hotspot (geology)|hotspot]] under the [[Galapagos Islands]] lies along the Galapagos Rise. (''see'' [[Galapagos hotspot]])
The [[Rivera Plate]] north of the Cocos Plate, is thought to have separated from the Cocos Plate 5-10 million years ago. The boundary between the two plates appears to lack a definite transform fault, yet they are regarded as distinct.
The devastating [[1985 Mexico City earthquake]] was a result of the subduction of the Cocos Plate beneath the North American Plate.
==References==
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==External links==
*[http://sio.ucsd.edu/volcano/expedition/cocos.html The volcanic arc]
*[http://www-odp.tamu.edu/publications/170_SR/VOLUME/CHAPTERS/SR170_07.PDF Martin Meschede and Udo Barckhausen, "Plate tectonic evolution of the Cocos-Nazca plate"]: reconstructing its geological evolution
{{Tectonic plates}}
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[[Category:Tectonic plates]]
[[Category:Geography of Central America]]
[[Category:Galápagos Islands]]
[[Category:Geography of Mexico]]
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