Mantle plume

plumemantle plumesplumesmagma conduitvolcanic plumeAntipodal hotspotGeophysical anomaliesmagma plumemantel upwellingmantle thermal plume
A mantle plume is a proposed mechanism of convection of abnormally hot rock within the Earth's mantle.wikipedia
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Hotspot (geology)

hotspothotspotshot spot
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps.
One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary.

Hawaii hotspot

Hawaiian hotspotHawaiiHawaiian volcanoes
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps.
One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the Hawaiian–Emperor seamount chain, a 5800 km mostly undersea volcanic mountain range.

Large igneous province

continental flood basaltlarge igneous provincesflood basalt province
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps. Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries or in large igneous provinces.
The formation of LIPs is variously attributed to mantle plumes or to processes associated with divergent plate tectonics.

Iceland hotspot

Iceland plumeIcelandhotspot
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps.
There is an ongoing discussion about whether the hotspot is caused by a deep mantle plume or originates at a much shallower depth.

Plate tectonics

tectonic platesplate tectonictectonic
Some such volcanic regions lie far from tectonic plate boundaries, while others represent unusually large-volume volcanism near plate boundaries or in large igneous provinces.
The theories find resonance in the modern theories which envisage hot spots or mantle plumes which remain fixed and are overridden by oceanic and continental lithosphere plates over time and leave their traces in the geological record (though these phenomena are not invoked as real driving mechanisms, but rather as modulators).

Flood basalt

basaltbasalt floodbasalt flow
These eruptions have been linked to flood basalts, although many of those erupt over much shorter time scales (less than 1 million years).
One proposed explanation for flood basalts is that they are caused by the combination of continental rifting and its associated decompression melting, in conjunction with a mantle plume also undergoing decompression melting, producing vast quantities of a tholeiitic basaltic magma.

W. Jason Morgan

William Jason MorganJason Morgan
The theory was first proposed by J. Tuzo Wilson in 1963 and further developed by W. Jason Morgan in 1971.
From 1971 on he worked on the further development of the plume theory of Tuzo Wilson, which postulates the existence of roughly cylindrical convective upwellings in the Earth's mantle as an explanation of hotspots.

Magma

magmaticmeltmagmas
This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.
The most common mechanisms of magma generation in the mantle are decompression melting, heating (e.g., by interaction with a hot mantle plume ), and lowering of the solidus (e.g., by compositional changes such as the addition of water ).

Columbia River Basalt Group

Columbia River BasaltColumbia River basaltsColumbia River basalt flows
Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly a single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America.
The ultimate cause of the volcanism is still up for debate, but the most widely accepted idea is that the mantle plume or upwelling (similar to that associated with present-day Hawaii) initiated the widespread and voluminous basaltic volcanism about 17 million years ago.

Geophysics

geophysicistgeophysicalgeophysicists
Some common and basic lines of evidence cited in support of the theory are linear volcanic chains, noble gases, geophysical anomalies, and geochemistry.
Some heat is carried up from the bottom of the mantle by mantle plumes.

Ontong Java Plateau

Ontong JavaOntong-Java PlateauGreater Ontong Java Event
Flood basalts in the oceans are known as oceanic plateaus, and include the Ontong Java plateau of the western Pacific Ocean and the Kerguelen Plateau of the Indian Ocean.
OJP formed quickly over a mantle plume head, most likely the then newly formed Louisville hotspot, followed by limited volcanism for at least 30 million years.

Lower mantle (Earth)

lower mantlelower part
Two very broad, large low-shear-velocity provinces, exist in the lower mantle under Africa and under the central Pacific.
The high pressure in the lower mantle has been shown to induce a spin transition of iron-bearing bridgmanite and ferropericlase, which may affect both mantle plume dynamics and lower mantle chemistry.

Deccan Traps

DeccanDeccan Trapvolcanism
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps. Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly a single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America.
It is postulated that the Deccan Traps eruption was associated with a deep mantle plume.

Mantle convection

convectionconvectingmantle convecting
The current mantle plume theory is that material and energy from Earth's interior are exchanged with the surface crust in two distinct modes: the predominant, steady state plate tectonic regime driven by upper mantle convection, and a punctuated, intermittently dominant, mantle overturn regime driven by plume convection.
Secondary convection may cause surface volcanism as a consequence of intraplate extension and mantle plumes.

Diapir

diapirismdiapirsdiapiric
A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust.
Diapirism in the mantle is thought to be associated with the development of large igneous provinces and some mantle plumes.

Paraná and Etendeka traps

Paraná TrapsParaná and EtendekaEtendeka
Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly a single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America.
Interpretations of geochemistry, including isotopes, have led geologists to conclude that the magmas forming the traps and associated igneous rocks originated by melting of asthenosphic mantle due to the arrival of a mantle plume to the base of Earth's lithosphere.

Tristan hotspot

TristanTristan da CunhaTristan da Cunha plume
Other "hot spots" with time-progressive volcanic chains behind them include Réunion, the Chagos-Laccadive Ridge, the Louisville Ridge, the Ninety East Ridge and Kerguelen, Tristan, and Yellowstone.
LLSVPs are dense and stable structures, and most of the plumes, kimberlites, and large igneous provinces (LIPs) on Earth can be rotated back to the PGZs.

Transition zone (Earth)

transition zone660 km discontinuitymantle transition zone
Seismic tomography shows that subducted oceanic slabs sink as far as the bottom of the mantle transition zone at 650 km depth.
From the Clapeyron slope the Moho discontinuity is expected to be shallower in cold regions, such as subducting slabs, and deeper in warmer regions, such as mantle plumes.

Hawaiian–Emperor seamount chain

Hawaiian-Emperor seamount chainEmperor SeamountsHawaiian – Emperor seamount chain
In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, would provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.
If the hotspot had remained above a fixed mantle plume during the past 80 million years, the latitude as recorded by the orientation of the ancient magnetic field preserved by magnetite (paleolatitude) should be constant for each sample; this should also signify original cooling at the same latitude as the current location of the Hawaiian hotspot.

Yellowstone hotspot

YellowstoneOwyhee-Humboldt volcanic fieldHeise volcanic field
Other "hot spots" with time-progressive volcanic chains behind them include Réunion, the Chagos-Laccadive Ridge, the Louisville Ridge, the Ninety East Ridge and Kerguelen, Tristan, and Yellowstone.
The appearance of "light" magmas would seem to indicate that the uppermost portion of the continental crust has largely been consumed by the earlier caldera- forming events, exhausting the melting potential of the crust above the mantle plume.

Ocean island basalt

OIBoceanic basaltsoceanic island basalts
"Ocean island basalt" is also similar to basalts found throughout the oceans on both small and large seamounts (thought to be formed by eruptions on the sea floor that did not rise above the surface of the ocean).
Many ocean island basalts erupt at volcanic hotspots, which are thought to be the surface expressions of melting of thermally buoyant, rising conduits of hot rock in the mantle, called mantle plumes.

Macdonald hotspot

Macdonald
Nonetheless, vertical plumes, 400 C hotter than the surrounding rock, were visualized under many hotspots, including the Pitcairn, Macdonald, Samoa, Tahiti, Marquesas, Galapagos, Cape Verde, and Canary hotspots.
Hotspots have been explained either by mantle plumes producing magma in the crust, reactivation of old lithospheric structures such as fractures or spreading of the crust through tectonic tension.

Igneous rock

igneousigneous rocksdecompression melting
Plumes are postulated to rise through the mantle and begin to partially melt on reaching shallow depths in the asthenosphere by decompression melting.
There, it is variously attributed either to the rise of mantle plumes (the "Plume hypothesis") or to intraplate extension (the "Plate hypothesis").

Upper mantle (Earth)

upper mantle
In the plate hypothesis, the slabs are postulated to have been recycled at shallower depths – in the upper few hundred kilometers that make up the upper mantle.
From the Clapeyron slope the Moho discontinuity is expected to be shallower in cold regions, such as subducting slabs, and deeper in warmer regions, such as mantle plumes.

Siberian Traps

Siberianvolcanic origins
Because the plume head partly melts on reaching shallow depths, a plume is often invoked as the cause of volcanic hotspots, such as Hawaii or Iceland, and large igneous provinces such as the Deccan and Siberian traps. Examples include the Deccan traps in India, the Siberian traps of Asia, the Karoo-Ferrar basalts/dolerites in South Africa and Antarctica, the Paraná and Etendeka traps in South America and Africa (formerly a single province separated by opening of the South Atlantic Ocean), and the Columbia River basalts of North America.
The source of the Siberian Traps basaltic rock has been attributed to a mantle plume, which rose until it impacted against the bottom of the Earth's crust, producing volcanic eruptions through the Siberian Craton.