Geochemical Constraints on Models of Mantle Dynamics

2013 ◽  
pp. 109-114
Author(s):  
Louis B. Nicolaysen
Keyword(s):  
Mantle Dynamics ◽  
Geochemical Constraints

EVIDENCE OF NEOPROTEROZOIC BACKARC BASIN DEVELOPMENT IN THE CENTRAL RIBEIRA BELT, SOUTHEASTERN BRAZIL: NEW GEOCHRONOLOGICAL AND GEOCHEMICAL CONSTRAINTS FROM THE SÃO ROQUE - AÇUNGUI GROUPS

2000 ◽  
Vol 30 (1) ◽  
pp. 110-114 ◽  
Author(s):  
PETER CHRISTIAN HACKSPACHER ◽  
ELTON LUIZ DANTAS ◽  
ANGELO SPOLADORE ◽  
ALLEN HUTCHESON FETTER ◽  
MARCOS AURÉLIO FARIA DE OLIVEIRA
Keyword(s):  
Southeastern Brazil ◽  
Backarc Basin ◽  
Basin Development ◽  
Geochemical Constraints

LITHOSPHERE STRUCTURE AND MANTLE DYNAMICS AT THE WESTERN EDGE OF THE LAURENTIAN CRATON

2020 ◽  
Author(s):  
Claire Currie ◽  
◽  
Andrew J. Schaeffer ◽  
Pascal Audet ◽  
Deirdre Mallyon
Keyword(s):  
Mantle Dynamics ◽  
Lithosphere Structure

Geological and isotopic geochemical constraints on the evolution of the Fuping Complex, North China Craton

2002 ◽  
Vol 117 (1-2) ◽  
pp. 41-56 ◽  
Author(s):  
Shuwen Liu ◽  
Yuanming Pan ◽  
Jianghai Li ◽  
Qiugen Li ◽  
Jian Zhang
Keyword(s):  
North China Craton ◽  
North China ◽  
Geochemical Constraints

scholarly journals Feedbacks between a non-Newtonian upper mantle, mantle viscosity structure and mantle dynamics

2020 ◽  
Vol 224 (2) ◽  
pp. 961-972
Author(s):  
A G Semple ◽  
A Lenardic
Keyword(s):  
Upper Mantle ◽  
Lower Mantle ◽  
Mantle Convection ◽  
Mantle Flow ◽  
Mantle Dynamics ◽  
Plate Motions ◽  
Low Viscosity ◽  
Mantle Viscosity ◽  
Flow Feature ◽  
Mantle Rheology

SUMMARY Previous studies have shown that a low viscosity upper mantle can impact the wavelength of mantle flow and the balance of plate driving to resisting forces. Those studies assumed that mantle viscosity is independent of mantle flow. We explore the potential that mantle flow is not only influenced by viscosity but can also feedback and alter mantle viscosity structure owing to a non-Newtonian upper-mantle rheology. Our results indicate that the average viscosity of the upper mantle, and viscosity variations within it, are affected by the depth to which a non-Newtonian rheology holds. Changes in the wavelength of mantle flow, that occur when upper-mantle viscosity drops below a critical value, alter flow velocities which, in turn, alter mantle viscosity. Those changes also affect flow profiles in the mantle and the degree to which mantle flow drives the motion of a plate analogue above it. Enhanced upper-mantle flow, due to an increasing degree of non-Newtonian behaviour, decreases the ratio of upper- to lower-mantle viscosity. Whole layer mantle convection is maintained but upper- and lower-mantle flow take on different dynamic forms: fast and concentrated upper-mantle flow; slow and diffuse lower-mantle flow. Collectively, mantle viscosity, mantle flow wavelengths, upper- to lower-mantle velocities and the degree to which the mantle can drive plate motions become connected to one another through coupled feedback loops. Under this view of mantle dynamics, depth-variable mantle viscosity is an emergent flow feature that both affects and is affected by the configuration of mantle and plate flow.

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