Nazca Plate

Coordinates: 15°S 85°W / 15°S 85°W / -15; -85
Source: Wikipedia, the free encyclopedia.
Nazca Plate
The Nazca Plate
TypeMinor
Approximate area15,600,000 km2[1]
Movement1north-east
Speed140-53 mm/year
FeaturesPacific Ocean
1Relative to the African Plate

The Nazca Plate or Nasca Plate,

volcanic islands as well as east–west running seamount chains that subduct under South America. Nazca is a relatively young plate both in terms of the age of its rocks and its existence as an independent plate having been formed from the break-up of the Farallon Plate about 23 million years ago. The oldest rocks of the plate are about 50 million years old.[3]

Boundaries

East Pacific and Chile Rise

A triple junction, the Chile Triple Junction,[4] occurs on the seafloor of the Pacific Ocean off Taitao and Tres Montes Peninsula at the southern coast of Chile. Here, three tectonic plates meet: the Nazca Plate, the South American Plate, and the Antarctic Plate.

Peru–Chile Trench

The eastern margin is a

Chile Rise, where seafloor spreading permits magma to rise. The western side is a divergent boundary with the Pacific Plate, forming the East Pacific Rise. The northern side is a divergent boundary with the Cocos Plate, the Galapagos Rise
.

The subduction of the Nazca plate under southern Chile has a history of producing massive earthquakes, including the largest ever recorded on earth, the moment magnitude 9.5 1960 Valdivia earthquake.

Intraplate features

Hotspots

A second triple junction occurs at the northwest corner of the plate where the Nazca, Cocos, and Pacific Plates all join off the coast of

Easter Island Microplate is a third microplate that is located just north of the Juan Fernandez Microplate and lies just west of Easter Island
.

Aseismic ridges

The Carnegie Ridge is a 1,350-kilometre-long (840 mi) and up to 300-kilometre-wide (190 mi) feature on the ocean floor of the northern Nazca Plate that includes the Galápagos archipelago at its western end. It is being subducted under South America with the rest of the Nazca Plate.

Plate motion

The absolute motion of the Nazca Plate has been calibrated at 3.7 cm/year (1.5 in/year) east motion (88°), one of the fastest absolute motions of any tectonic plate. The subducting Nazca Plate, which exhibits unusual flat slab subduction, is tearing as well as deforming as it is subducted (Barzangi and Isacks). The subduction has formed, and continues to form, the volcanic Andes Mountain Range. Deformation of the Nazca Plate even affects the geography of Bolivia, far to the east (Tinker et al.). The 1994 Bolivia earthquake occurred on the Nazca Plate; this had a magnitude of 8.2 , which at that time was the strongest instrumentally recorded earthquake occurring deeper than 300 km (190 mi).

Aside from the Juan Fernández Islands, this area has very few other islands that are affected by the earthquakes that are a result of complicated movements at these junctions.

Geologic history

The precursor of the Nazca Plate,

magnetic anomalies. Subduction under the South American continent began about 140 Mya, although the formation of the high parts of the Central Andes and the Bolivian orocline did not occur until 45 Mya. It has been suggested that the mountains were forced up by the subduction of the older and heavier parts of the plate, which sank more quickly into the mantle.[5]

See also

References

  1. ^ "Sizes of Tectonic or Lithospheric Plates". About.com Geology. Archived from the original on 9 February 2007. Retrieved 4 January 2016.
  2. .
  3. ^ Dutch, Steven (10 August 2009). "Sea Floor Spreading in the Pacific (Plate Boundaries Shown)". University of Wisconsin - Green Bay. Archived from the original on 17 March 2010.
  4. ^ Kelly McGuire (8 April 2004). "Tectonics of South America: Chile Triple Junction" (PDF). Archived (PDF) from the original on 19 January 2020. Retrieved 27 February 2016.
  5. ^ "Mountains on a plate form the Andes". No. 214. University World News. 25 March 2012. Archived from the original on 13 September 2015. Retrieved 8 February 2016.

Bibliography

15°S 85°W / 15°S 85°W / -15; -85