The North American Plate is a
tectonic plate
Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...
covering most of
North America,
Cuba
Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...
,
the Bahamas
The Bahamas (), officially the Commonwealth of The Bahamas, is an island country within the Lucayan Archipelago of the West Indies in the North Atlantic. It takes up 97% of the Lucayan Archipelago's land area and is home to 88% of the ar ...
, extreme northeastern
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...
, and parts of
Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...
and
the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the
Pacific Plate (which borders the plate to the west).
It extends eastward to the
Mid-Atlantic Ridge and westward to the
Chersky Range in eastern Siberia. The plate includes both
continental
Continental may refer to:
Places
* Continent, the major landmasses of Earth
* Continental, Arizona, a small community in Pima County, Arizona, US
* Continental, Ohio, a small town in Putnam County, US
Arts and entertainment
* ''Continental'' ( ...
and
oceanic crust. The interior of the main continental landmass includes an extensive
granitic
A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz- ...
core called a
craton. Along most of the edges of this craton are fragments of crustal material called
terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...
s, which are
accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the
Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
is composed of such terranes.
Boundaries
The southern boundary with the
Cocos Plate to the west and the
Caribbean Plate to the east is a
transform fault
A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduct ...
, represented by the
Swan Islands Transform Fault under the
Caribbean Sea
The Caribbean Sea ( es, Mar Caribe; french: Mer des Caraïbes; ht, Lanmè Karayib; jam, Kiaribiyan Sii; nl, Caraïbische Zee; pap, Laman Karibe) is a sea of the Atlantic Ocean in the tropics of the Western Hemisphere. It is bounded by Mexico ...
and the
Motagua Fault through
Guatemala. The parallel
Septentrional and
Enriquillo–Plantain Garden faults, which run through the island of
Hispaniola and bound the
Gonâve Microplate, are also a part of the boundary. The rest of the southerly margin which extends east to the Mid Atlantic Ridge and marks the boundary between the North American Plate and the
South American Plate is vague but located near the
Fifteen-Twenty Fracture Zone
The Fifteen-Twenty or 15°20' Fracture Zone (FTFZ), also known as the Cabo Verde Fracture Zone, is a fracture zone located on the Mid-Atlantic Ridge (MAR) in the central Atlantic Ocean between 14–16°N. It is the current location of the migrati ...
around 16°n.
On the northerly boundary is a continuation of the Mid-Atlantic ridge called the
Gakkel Ridge. The rest of the boundary in the far northwestern part of the plate extends into
Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive region, geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a ...
. This boundary continues from the end of the Gakkel Ridge as the
Laptev Sea Rift, on to a transitional deformation zone in the
Chersky Range, then the
Ulakhan Fault between it and the
Okhotsk Plate, and finally the
Aleutian Trench
The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulak ...
to the end of the
Queen Charlotte Fault system.
The westerly boundary is the
Queen Charlotte Fault running offshore along the coast of
Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...
and the
Cascadia subduction zone
The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, a ...
to the north, the
San Andreas Fault
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizonta ...
through
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, the
East Pacific Rise in the
Gulf of California, and the
Middle America Trench to the south.
On its western edge, the
Farallon Plate
The Farallon Plate was an ancient oceanic plate. It formed one of the three main plates of Panthalassa, alongside the Phoenix Plate and Izanagi Plate, which were connected by a triple junction. The Farallon Plate began subducting under the west ...
has been
subducting
Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...
under the North American Plate since the
Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of ...
Period. The Farallon Plate has almost completely subducted beneath the western portion of the North American Plate, leaving that part of the North American Plate in contact with the Pacific Plate as the
San Andreas Fault
The San Andreas Fault is a continental transform fault that extends roughly through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizonta ...
. The
Juan de Fuca
Juan de Fuca (10 June 1536, Cefalonia 23 July 1602, Cefalonia)Greek Consulate of Vancouver,Greek Pioneers: Juan de Fuca. was a Greek pilot who served PhilipII of Spain. He is best known for his claim to have explored the Strait of Aniánnow k ...
,
Explorer
Exploration refers to the historical practice of discovering remote lands. It is studied by geographers and historians.
Two major eras of exploration occurred in human history: one of convergence, and one of divergence. The first, covering most ...
,
Gorda,
Rivera,
Cocos and
Nazca plates are remnants of the Farallon Plate.
The boundary along the
Gulf of California is complex. The Gulf is underlain by the
Gulf of California Rift Zone, a series of rift basins and transform fault segments from the northern end of the
East Pacific Rise in the mouth of the gulf to the San Andreas Fault system in the vicinity of the
Salton Trough
The Salton Trough is an active tectonic pull-apart basin, or graben. It lies within the Imperial, Riverside, and San Diego counties of southeastern California, United States and extends south of the Mexico–United States border into the stat ...
rift/
Brawley seismic zone.
It is generally accepted that a piece of the North American Plate was broken off and transported north as the East Pacific Rise propagated northward, creating the Gulf of California. However, it is as yet unclear whether the oceanic crust between the Rise and the mainland coast of Mexico is actually a new plate beginning to converge with the North American Plate, consistent with the standard model of rift zone spreading centers generally.
Hotspots
A few
hotspots are thought to exist below the North American Plate. The most notable hotspots are the
Yellowstone (Wyoming),
Jemez Lineament (New Mexico), and
Anahim (British Columbia) hotspots. These are thought to be caused by a narrow stream of
hot mantle convecting up from the Earth's
core–mantle boundary
The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2,891 km (1,796 miles) depth beneath Earth's surface. The boundary is observed ...
called a
mantle plume
A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hot ...
,
although some geologists think that
upper mantle
The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle at . Temperatures range from appr ...
convection is a more likely cause. The Yellowstone and Anahim hotspots are thought to have first arrived during the
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
period and are still geologically active, creating
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...
s and
volcano
A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface.
On Ear ...
es. The Yellowstone hotspot is most notable for the
Yellowstone Caldera and the many
caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
s that lie in the
Snake River Plain while the Anahim hotspot is most notable for the
Anahim Volcanic Belt, currently found in the
Nazko Cone
Nazko Cone is a small potentially active basaltic cinder cone in central British Columbia, Canada, located 75 km west of Quesnel and 150 kilometers southwest of Prince George. It is considered the easternmost volcano in the Anahim Volcanic ...
area.
Plate motion
For the most part, the North American Plate moves in roughly a southwest direction away from the Mid-Atlantic Ridge at a rate of about 2.3 centimeters (~1 inch) per year. At the same time, the Pacific Plate is moving to the northwest at a speed of between 7 and 11 centimeters (~3-4 inches) a year.
The motion of the plate cannot be driven by subduction as no part of the North American Plate is being subducted, except for a small section comprising part of the
Puerto Rico Trench
The Puerto Rico Trench is located on the boundary between the Caribbean Sea and the Atlantic Ocean. The oceanic trench, the deepest in the Atlantic, is associated with a complex transition between the Lesser Antilles subduction zone to the sou ...
; thus other mechanisms continue to be investigated.
One recent study suggests that a mantle convective current is propelling the plate.
See also
*
Geologic timeline of Western North America
*
New Madrid Seismic Zone
The New Madrid Seismic Zone (), sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching t ...
, an ancient intraplate fault zone within the North American Plate, notable as early as 1699
References
;Notes
{{Tectonic plates
Tectonic plates
Geology of North America
Geology of Russia
Geology of Greenland
Geology of California
Geology of Iceland
Geology of the Atlantic Ocean
Geology of the Pacific Ocean