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However, paleomagnetic data show that mantle plumes can also be associated with Large Low Shear Velocity Provinces (LLSVPs) [7] [8] and do move relative to each other. [9] The current mantle plume theory is that material and energy from Earth's interior are exchanged with the surface crust in two distinct and largely independent convective flows:
The volcanism often attributed to deep mantle plumes is alternatively explained by passive extension of the crust, permitting magma to leak to the surface: the plate hypothesis. [24] The convection of the Earth's mantle is a chaotic process (in the sense of fluid dynamics), which is
High-magnesium magmas, such as komatiite and picrite, may also be the products of a high degree of partial melting of mantle rock. [83] Certain chemical elements, called incompatible elements, have a combination of ionic radius and ionic charge that is unlike that of the more abundant elements in the source rock. The ions of these elements fit ...
Mantle plumes were first proposed by J. Tuzo Wilson in 1963 [4] [non-primary source needed] and further developed by W. Jason Morgan in 1971. A mantle plume is posited to exist where hot rock nucleates [clarification needed] at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. [5]
The formation and development of plumes in the early mantle contributed to triggering the lateral movement of crust across the Earth's surface. [18] The effect of upwelling mantle plumes on the lithosphere can be seen today through local depressions around hotspots such as Hawaii. The scale of this impact is much less than that exhibited in the ...
Another proposed origin for the LLSVPs is that their formation is related to the giant-impact hypothesis, which states that the Moon formed after the Earth collided with a planet-sized body called Theia. [15] The hypothesis suggests that the LLSVPs may represent fragments of Theia's mantle which sank through to Earth's core-mantle boundary. [15]
Earth's crust and mantle, Mohorovičić discontinuity between bottom of crust and solid uppermost mantle. Earth's mantle extends to a depth of 2,890 km (1,800 mi), making it the planet's thickest layer. [20] [This is 45% of the 6,371 km (3,959 mi) radius, and 83.7% of the volume - 0.6% of the volume is the crust].
After magma is generated, magma will migrate out of its source region by the process of magma segregation and extraction. These processes define the resulting composition of the magma. Depending on the efficiency of the segregation and extraction, there will be different structures of the volcanic and igneous plumbing systems. [6]