scholarly journals Constraints on Mantle Convection From Seismic Tomography

2000 ◽  
pp. 277-288 ◽  
Author(s):  
Hrafnkell Kárason ◽  
Rob D. van der Hilst
Keyword(s):  
Seismic Tomography ◽  
Mantle Convection

New Mantle Convection Models Constrained by Seismic Tomography Data

2003 ◽  
Vol 46 (6) ◽  
pp. 1106-1113 ◽  
Author(s):  
Rongshan FU ◽  
Jianhua HUANG ◽  
Shuqian DONG ◽  
Xiaohua CHANG
Keyword(s):  
Seismic Tomography ◽  
Mantle Convection ◽  
Tomography Data

scholarly journals Compositional mantle layering revealed by slab stagnation at ~1000-km depth

2015 ◽  
Vol 1 (11) ◽  
pp. e1500815 ◽  
Author(s):  
Maxim D. Ballmer ◽  
Nicholas C. Schmerr ◽  
Takashi Nakagawa ◽  
Jeroen Ritsema
Keyword(s):  
Numerical Modeling ◽  
Seismic Tomography ◽  
Upper Mantle ◽  
Lower Mantle ◽  
Mantle Convection ◽  
Global Scale ◽  
Compositional Gradient ◽  
Mantle Enrichment ◽  
Geodynamic Models ◽  
Neutrally Buoyant

Improved constraints on lower-mantle composition are fundamental to understand the accretion, differentiation, and thermochemical evolution of our planet. Cosmochemical arguments indicate that lower-mantle rocks may be enriched in Si relative to upper-mantle pyrolite, whereas seismic tomography images suggest whole-mantle convection and hence appear to imply efficient mantle mixing. This study reconciles cosmochemical and geophysical constraints using the stagnation of some slab segments at ~1000-km depth as the key observation. Through numerical modeling of subduction, we show that lower-mantle enrichment in intrinsically dense basaltic lithologies can render slabs neutrally buoyant in the uppermost lower mantle. Slab stagnation (at depths of ~660 and ~1000 km) and unimpeded slab sinking to great depths can coexist if the basalt fraction is ~8% higher in the lower mantle than in the upper mantle, equivalent to a lower-mantle Mg/Si of ~1.18. Global-scale geodynamic models demonstrate that such a moderate compositional gradient across the mantle can persist can in the presence of whole-mantle convection.

scholarly journals Mantle Convection and Possible Mantle Plumes beneath Antarctica - Insights from Geodynamic Models and Implications for Topography

2021 ◽  
pp. M56-2020-2
Author(s):  
Eva Bredow ◽  
Bernhard Steinberger
Keyword(s):  
Mantle Plume ◽  
Seismic Tomography ◽  
Mantle Convection ◽  
Large Scale ◽  
Shear Velocity ◽  
Mantle Flow ◽  
Mantle Plumes ◽  
Dynamic Topography ◽  
West Antarctica ◽  
Geodynamic Models

AbstractThis chapter describes the large-scale mantle flow structures beneath Antarctica as derived from global seismic tomography models of the present-day state. In combination with plate reconstructions, the time-dependent pattern of paleosubduction can be simulated and is also shown from the rarely seen Antarctic perspective. Furthermore, a dynamic topography model demonstrates which kind and scales of surface manifestations can be expected as a direct and observable result of mantle convection. The last section of the chapter features an overview of the classical concept of deep-mantle plumes from a geodynamic point of view and how recent insights, mostly from seismic tomography, have changed the understanding of plume structures and dynamics over the past decades. The long-standing and controversial hypothesis of a mantle plume beneath West Antarctica is summarised and addressed with geodynamic models, which estimate the excess heat flow of a potential plume at the bedrock surface. However, the predicted heatflow is small while differences in surface heat flux estimates are large, therefore the results are not conclusive with regard to the existence of a West Antarctic mantle plume. Finally, it is shown that global mantle flow would cause tilting of whole-mantle plume conduits beneath West Antarctica such that their base is predicted to be displaced about northward relative to the surface position, closer to the southern margin of the Pacific Large Low Shear Velocity Province.

PLANETARY SELF-ORGANIZATION

2020 ◽  
Vol 42 (3) ◽  
pp. 271-282
Author(s):  
OLEG IVANOV
Keyword(s):  
Dynamical System ◽  
Heat Source ◽  
Mantle Convection ◽  
Plate Tectonics ◽  
Rotation Speed ◽  
Self Organization ◽  
Heat Sources ◽  
Kinematic Parameters ◽  
The Earth ◽  
New Type

The general characteristics of planetary systems are described. Well-known heat sources of evolution are considered. A new type of heat source, variations of kinematic parameters in a dynamical system, is proposed. The inconsistency of the perovskite-post-perovskite heat model is proved. Calculations of inertia moments relative to the D boundary on the Earth are given. The 9 times difference allows us to claim that the sliding of the upper layers at the Earth's rotation speed variations emit heat by viscous friction.This heat is the basis of mantle convection and lithospheric plate tectonics.

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