The Caroline Plate is a minor

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 t ...

that straddles the Equator in the

eastern hemisphere The Eastern Hemisphere is the half of the planet Earth which is east of the prime meridian (which crosses Greenwich, London, United Kingdom) and west of the antimeridian (which crosses the Pacific Ocean and relatively little land from pole to po ...

located north of

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

. It forms a

subduction zone 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, ...

along the border with the Bird's Head Plate and the Woodlark Plate to the south. A transform boundary forms the northern border with the

Pacific Plate The Pacific Plate is an oceanic tectonic plate 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, and I ...

. Along the border with 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 of ...

is 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 ...

that transitions into a

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

. The Caroline Plate was first proposed as a distinct plate by .

Geological setting

A separate

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its ow ...

with its own tectonic history, the Caroline Plate has been considered part of the

because of sparse seismicity and low velocities along its boundaries. It includes the

West West or Occident is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sun sets on the Earth. Etymology The word "west" is a Germanic word passed into some ...

and

East Caroline East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the fa ...

basins and the inactive Eauripik Rise separating them, but neither the

Caroline Islands The Caroline Islands (or the Carolines) are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically, they are divided between the Federated States of Micronesia (FSM) in the centra ...

nor the

Caroline Ridge Caroline may refer to: People *Caroline (given name), a feminine given name * J. C. Caroline (born 1933), American college and National Football League player * Jordan Caroline (born 1996), American (men's) basketball player Places Antarctica *Ca ...

. It is subducting under the Bird's Head and Woodlark plates along the New Guinea Trench to the south. The boundary with the

Philippine Sea The Philippine Sea is a marginal sea of the Western Pacific Ocean east of the Philippine archipelago (hence the name), the largest in the world, occupying an estimated surface area of . The Philippine Sea Plate forms the floor of the sea. Its ...

to the west has two segments: the southern segment, the

Ayu Trough Ayu or AYU may refer to: * Ayu (given name) * Ayu sweetfish (''Plecoglossus altivelis''), a species of smelt * ''Ayu'', a local name for the African manatee * Ayu (singer) or Ayumi Hamasaki, Japanese singer * Ayu Islands, a small archipelago i ...

was spreading at a rate of 8 mm/yr 25–2 Ma but has been slowing down since. The northern segment, the

Palau Palau,, officially the Republic of Palau and historically ''Belau'', ''Palaos'' or ''Pelew'', is an island country and microstate in the western Pacific. The nation has approximately 340 islands and connects the western chain of the Ca ...

and southern Yap trenches, is not an active subduction zone as indicated by the lack of active

volcanoes A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

. The Caroline-

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

boundary is a complex, evolving system partly and potentially developing into a subduction zone. The south-east boundary, along the Manus Trench, is a convergent boundary, but in the absence of active volcanoes and earthquakes, is not a subduction zone at present.

Tectonic history

The Caroline Plate moves at velocities very close to those of the Pacific Plate and its age of formation and current status as an independent plate are uncertain. There is a very slow rate of spreading between the Caroline and Philippine plates but the Caroline Plate apparently moved together with both the Philippine and New Guinea plates during the Neogene. The Caroline Ridge, to the north, meets the Caroline Plate at the Sorol Trough at which there some evidence of oblique extension; the Caroline Ridge, however, is, although of uncertain origin, made of oceanic crust and probably the product of a hotspot. The presence of a trench and indications of subduction beneath the Pacific Plate is suggestive but the absence of island arcs, which could be expected from substantial subduction in the past, makes the development along this boundary unclear. The Caroline Plate was, under all circumstances, a separate plate in the past. The boundary along its eastern side, the Mussau Trench, must have been an important boundary since magnetic anomalies on the Caroline Plate are Oligocene but those on the Pacific Plate Cretaceous. There are indications of spreading in the Caroline Sea 34–27 Ma. If the Caroline Plate moved with the Pacific Plate there should be clear evidences of a corresponding subduction beneath New Guinea, of which there is virtually none. The Ayu Trough is a slow spreading zone that opened 15 Ma.

References

Notes

Sources

* * ** * * * {{DEFAULTSORT:Caroline Plate Tectonic plates Geology of the Pacific Ocean