The Pacific Plate is an oceanic

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 ...

that lies beneath the Pacific Ocean. At , it is the largest tectonic plate. The plate first came into existence 190 million years ago, at the triple junction between the Farallon,

Phoenix Phoenix most often refers to: * Phoenix (mythology), a legendary bird from ancient Greek folklore * Phoenix, Arizona, a city in the United States Phoenix may also refer to: Mythology Greek mythological figures * Phoenix (son of Amyntor), a ...

, and Izanagi Plates. The Pacific Plate subsequently grew to where it underlies most of the Pacific Ocean basin. This reduced the Farallon Plate to a few remnants along the west coast of North America and the Phoenix Plate to a small remnant near the

Drake Passage The Drake Passage (referred to as Mar de Hoces Hoces Sea"in Spanish-speaking countries) is the body of water between South America's Cape Horn, Chile and the South Shetland Islands of Antarctica. It connects the southwestern part of the Atla ...

, and destroyed the Izanagi Plate by subduction under Asia. The Pacific Plate contains an interior hot spot forming the

Hawaiian Islands The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...

Boundaries

The north-eastern side is a divergent boundary with the

Explorer Plate The Explorer Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada, which is partially subducted under the North American Plate. Along with the Juan de Fuca Plate and Gorda Plate, the Explor ...

, the Juan de Fuca Plate and the

Gorda Plate The Gorda Plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon Plate. It is sometimes referred to (by, for example, publications from the USGS Earthquake Hazards Program) a ...

forming respectively the

Explorer Ridge The Explorer Ridge is a mid-ocean ridge, a divergent tectonic plate boundary located about west of Vancouver Island, British Columbia, Canada. It lies at the northern extremity of the Pacific spreading axis. To its east is the Explorer Plate, ...

, the

Juan de Fuca Ridge The Juan de Fuca Ridge is a mid-ocean spreading center and divergent plate boundary located off the coast of the Pacific Northwest region of North America. The ridge separates the Pacific Plate to the west and the Juan de Fuca Plate to the east ...

and the

Gorda Ridge The Gorda Ridge (41°36'19.6"N 127°22'03.1"W), aka ''Gorda Ridges'' tectonic spreading center, is located roughly off the northern coast of California and southern Oregon. Running NE – SW it is roughly in length.Carey, Stein, & Rona. (1990). ...

. In the middle of the eastern side is a

transform boundary 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 subductio ...

with the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacif ...

along 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 ...

, and a boundary with the

Cocos Plate The Cocos Plate is a young 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 was created approximately 23 million years ago when the Farallon Plate ...

. The south-eastern side is a divergent boundary with the Nazca Plate forming the

East Pacific Rise The East Pacific Rise is a mid-ocean rise (termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), a divergent tectonic plate boundary located alon ...

. The southern side is a divergent boundary with the

Antarctic Plate The Antarctic Plate is a tectonic plate containing the continent of Antarctica, the Kerguelen Plateau, and some remote islands in the Southern Ocean and other surrounding oceans. After breakup from Gondwana (the southern part of the superconti ...

forming the

Pacific–Antarctic Ridge The Pacific-Antarctic Ridge (PAR) is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. It is regarded as the southern section of the East Pacific Rise ...

. The western side is bounded by the

Okhotsk Plate The Okhotsk Plate is a minor tectonic plate covering the Kamchatka Peninsula, Magadan Oblast, and Sakhalin Island of Russia; Hokkaido, Kantō and Tōhoku regions of Japan; the Sea of Okhotsk, as well as the disputed Kuril Islands. It was ...

at the

Kuril–Kamchatka Trench The Kuril–Kamchatka Trench or Kuril Trench (russian: Курило-Камчатский жёлоб, ''Kurilo-Kamchatskii Zhyolob'') is an oceanic trench in the northwest Pacific Ocean. It lies off the southeast coast of Kamchatka and parallels ...

and the

Japan Trench The Japan Trench is an oceanic trench part of the Pacific Ring of Fire off northeast Japan. It extends from the Kuril Islands to the northern end of the Izu Islands, and is at its deepest. It links the Kuril–Kamchatka Trench to the north and ...

. The plate forms a

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

by subducting under the

Philippine Sea Plate The Philippine Sea Plate or the Philippine Plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part o ...

creating the

Mariana Trench The Mariana Trench is an oceanic trench located in the western Pacific Ocean, about east of the Mariana Islands; it is the deepest oceanic trench on Earth. It is crescent-shaped and measures about in length and in width. The maximum known ...

, has a

with the

Caroline Plate The Caroline Plate is a minor tectonic plate that straddles the Equator in the eastern hemisphere located north of New Guinea. It forms a subduction zone along the border with the Bird's Head Plate and the Woodlark Plate to the south. A transfo ...

, and has a collision boundary with the

North Bismarck Plate The North Bismarck Plate is a small tectonic plate located in the Bismarck Sea off the northeast coast of New Guinea. Tectonics To the north it collides with the Pacific Plate and the Caroline Plate, part of the western part subducts under the W ...

. In the south-west, the Pacific Plate has a complex but generally convergent boundary with the

Indo-Australian Plate The Indo-Australian Plate is a major tectonic plate that includes the continent of Australia and the surrounding ocean and extends northwest to include the Indian subcontinent and the adjacent waters. It was formed by the fusion of the Indian an ...

, subducting under it north of New Zealand forming the Tonga Trench and the

Kermadec Trench The Kermadec Trench is a linear ocean trench in the south Pacific Ocean. It stretches about from the Louisville Seamount Chain in the north (26°S) to the Hikurangi Plateau in the south (37°S), north-east of New Zealand's North Island. Toget ...

. The

Alpine Fault The Alpine Fault is a geological fault that runs almost the entire length of New Zealand's South Island (c. 480 km) and forms the boundary between the Pacific Plate and the Indo-Australian Plate. The Southern Alps have been uplifted on the f ...

marks a

between the two plates, and further south the Indo-Australian Plate subducts under the Pacific Plate forming the

Puysegur Trench The deepStern, Robert J. (2004)Subduction initiation: spontaneous and induced Earth and Planetary Science Letters 226, 275–292. . Puysegur Trench is a deep cleft in the floor of the south Tasman Sea formed by the subduction of the Indo-Austral ...

. The southern part of

Zealandia Zealandia (pronounced ), also known as (Māori) or Tasmantis, is an almost entirely submerged mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago.Gurnis, M., Hall, C.E., and Lavier, L.L., ...

, which is to the east of this boundary, is the plate's largest block of continental crust. Hillis and Müller are reported to consider the

Bird's Head Plate The Bird's Head Plate is a minor tectonic plate incorporating the Bird's Head Peninsula, at the western end of the island of New Guinea. Hillis and Müller consider it to be moving in unison with the Pacific Plate. Bird considers it to be unconne ...

to be moving in unison with the Pacific Plate, but Bird considers them to be unconnected. The northern side is a

subducting under the

forming 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 ...

and the corresponding

Aleutian Islands The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a chain of 14 large v ...

Paleo-geology of the Pacific Plate

The Pacific Plate is almost entirely

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...

, but it contains some

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' be ...

in New Zealand,

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

, and coastal

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. The Pacific Plate has the distinction of showing one of the largest areal sections of the oldest members of seabed geology being entrenched into eastern Asian

oceanic trench Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...

es. A geologic map of the Pacific Ocean seabed shows not only the geologic sequences, and associated

Ring of Fire The Ring of Fire (also known as the Pacific Ring of Fire, the Rim of Fire, the Girdle of Fire or the Circum-Pacific belt) is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring o ...

zones on the ocean's perimeters, but the various ages of the seafloor in a stairstep fashion, youngest to oldest, the oldest being consumed into the Asian oceanic trenches. The oldest part disappearing by way of the

plate tectonics 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 ...

cycle is early-

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

(145 to 137 million years ago). The Pacific Plate originated at the

triple junction A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of three types – a ridge (R), trench (T) or transform fault (F) – and triple junctions can ...

of the three main oceanic plates of

Panthalassa Panthalassa, also known as the Panthalassic Ocean or Panthalassan Ocean (from Greek "all" and "sea"), was the superocean that surrounded the supercontinent Pangaea, the latest in a series of supercontinents in the history of Earth. During th ...

, the Farallon,

, and Izanagi Plates, around 190 million years ago. The plate formed because the triple junction had converted to an unstable form surrounded on all sides by

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 ...

s, due to the development of a kink in one of the plate boundaries. The "Pacific Triangle", the oldest part of the Pacific Plate, created during the initial stages of plate formation, is located just east of the

. The growth of the Pacific Plate reduced the Farallon Plate to a few remnants along the west coast of North America (such as the Juan de Fuca Plate) and the Phoenix Plate to a small remnant near the

, and destroyed the Izanagi Plate by subduction under Asia.

References

External links

Age of the Ocean Floor
{{Tectonic plates Tectonic plates Geology of the Pacific Ocean Natural history of North America Natural history of Hawaii Natural history of Oceania Natural history of Japan Geology of the Russian Far East Geology of California Geology of New Zealand