Which of these combines with changes in a fluids density and the force of gravity to set convection currents in motion answer choicesFreezing and melting of a solidHeating and cooling of a fluid.
A wide range of geophysical and geochemical observations pertaining to convection in the earths mantle and the dynamics of the tectonic plates is discussedIt is inferred that the dominant mode of mantle convection is a platescale flow and that the plates are an integral part of this flow.
Conditions particularly favourable to largescale partial fusion of the upper mantle occur in the topmost section of a rising convection currentThis should result in abundant igneous activity and local areas of anomalously high heat flowThis supports the view that ocean ridges overlie uprising convection currentsBelts of relatively low heat flow adjacent to the ocean ridges are difficult to explain if the convecting mantle behaves as a Newtonian viscous fluid but are explicable on the nonNewtonian model of convection recently suggested by Orowan.
Heat flow along lower left and across lower right the Hawaiian SwellHeat flow though anomalously high with respect to the PSM model is at most slightly above that expected for GDH1 Stein and Stein 1993Material properties for mantle convection consistent with observed surface fields J.
Heat transported by these plumes that are entirely controlled by two nondimensional pa seen at the surface can therefore not be a correct rameters Ra the classical Rayleigh number for estimate of core heat loss even in a mantle with convection between horizontal plates at 162xed tem out any additional complexity such as chemical or peratures e.
Hot spots are considered to represent the surface manifestation of plumes of hot material that rise from very deep within the mantle drill through the lithosphere and emerge as volcanic centers on either the sea floor or on continental crust.
Jan 28 2000nbsp018332MANTLE PLUMES DYNAMICS AND GEOCHEMICALMantle plumes constitute a secondary type of convectionTheir total heat flow represents 10 of the mantle heat loss corresponding aproximately to 8 of the global Earth ́s heat budget.
Mantle convection Introduction and History All planetary bodies retain some heat from their early formation but are inexorably cooling to spacePlanetary surfaces are therefore cold relative to their hotter interiors and thus undergo thermal convection wherein cold material is dense and sinks while hot material is light and rises liquid.
Mantle plumes are geochemically heterogeneous incorporating deeply recycled subducted components primordial mantle domains and potentially materials from Earth’s core.
Mar 11 2020nbsp018332This flow called mantle convection is an important method of heat transport within the EarthMantle convection is the driving mechanism for plate tectonics which is the process ultimately responsible for producing earthquakes mountain ranges and volcanos on EarthSubsequently question is which processes are caused by convection.
May 25 2021nbsp018332Mantle plumes are an integral aspect of Earth’s convection system yet difficulty in imaging mantle upwellings led to controversies surrounding their origin dynamics and composition.
Oct 19 2020nbsp018332Abstract All known mantle plumes are characterized by a divergence between the location of the extreme heat flow and the recent volcanism centerTo explain this phenomenon it is proposed to consider the Coriolis effect influence which deflects the magma flow within a mantle plume from the trajectory that is orthogonal to the planet surface.
The anomalous low heat flow of PreCambrian shields suggests absence of convection in the mantle beneath since the PreCambrianConditions particularly favourable to largescale partial fusion of the upper mantle occur in the topmost section of a rising convection current.
The higher heat flow values on oceanic crust than continental crust indicate that most of the heat leaving Earths interior is coming from the mantleThe very low heat conductivity of mantle rocks precludes this heat from reaching the surface by conductionThe measured heat flow values are consistent with mantle convection.
The mantle heat flow recorded in xenoliths from 210 km thick Archaean cratons is 1418 mWm2 compared to 3034 mWm2 in 100 km thick Phanerozoic mantleThe observation that there must be an inverse relation between the thickness of the lithosphere and the underlying convecting layer can account for this substantial difference in heat flow.
The term convection is often used to describe heat transfer that occurs between an object and a fluid flowing across itConvection is in essence a type of conductionIn convection heat is transported mostly by the movement of material rather than by conductionConvection in the Earths mantle is the transport of heat by motion of the mantle.
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