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Simplified model of mantle convection: [1] Whole-mantle convection. Mantle convection is the very slow creep of Earth's solid silicate mantle as convection currents carry heat from the interior to the planet's surface. [2] [3] Mantle convection causes tectonic plates to move around the Earth's surface. [4] The Earth's lithosphere rides atop the ...
Convection is usually the dominant form of heat transfer in liquids and gases. Note that this definition of convection is only applicable in Heat transfer and thermodynamic contexts. It should not be confused with the dynamic fluid phenomenon of convection , which is typically referred to as Natural Convection in thermodynamic contexts in order ...
Typically this is caused by a variable composition of the fluid. If the varying property is a concentration gradient, it is known as solutal convection. [5] For example, gravitational convection can be seen in the diffusion of a source of dry salt downward into wet soil due to the buoyancy of fresh water in saline. [6]
It is because of these forces, slab pull, ridge push, mantle convection, and slab suction that the Earth's crust is able to move and orient itself in various arrangements. This is how throughout the Earth's history there has been the ability to create super continents where all of the land mass has converged into one (for example, Pangaea).
[11] [12] Marianas Trench is an example of a deep slab, thereby creating the deepest trench in the world established by a steep slab angle. [13] Slab breakoff occurs during a collision between oceanic and continental lithosphere, [ 14 ] allowing for a slab tear; an example of slab breakoff occurs within the Himalayan subduction zone.
Iceland is the type example of a volcanic anomaly situated on a plate boundary. Yellowstone, together with the Eastern Snake River Plain to its west, is the type example of an intra-continental volcanic anomaly. Hawaii, along with the related Hawaiian-Emperor seamount chain, is the type example of an intra-oceanic volcanic anomaly. [7]
Numerical models of mantle convection in which the viscosity is dependent both on temperature and strain rate reliably produce an oceanic asthenosphere, suggesting that strain-rate weakening is a significant contributing mechanism, [24] and explaining the particularly weak asthenosphere below the Pacific plate. [23]
Melts are produced when mantle rocks bear temperatures between 1100 and 2400 °C at corresponding depths (pressure varies the melting temperature) with the presence of water. [ 11 ] [ 12 ] When melts reach surface via vertical vents, they cool down and solidify forming mafic or ultramafic rocks which are rich in iron and magnesium .