scholarly journals Mantle dynamics beneath Mongolia: implications from Cenozoic and Mesozoic alkalic basalts

2019 ◽  
Keyword(s):  
Mantle Dynamics ◽  
Alkalic Basalts

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

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.

Tholeiitic and alkalic basalts of the Eocene Siletz River Volcanics, Oregon Coast Range

1968 ◽  
Vol 266 (6) ◽  
pp. 454-481 ◽  
Author(s):  
P. D. Snavely ◽  
N. S. MacLeod ◽  
H. C. Wagner
Keyword(s):  
Coast Range ◽  
Oregon Coast Range ◽  
Oregon Coast ◽  
Alkalic Basalts

The Heterogeneous Tethyan Oceanic Lithosphere of the Alpine Ophiolites

Elements ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Elisabetta Rampone ◽  
Alessio Sanfilippo
Keyword(s):  
Oceanic Lithosphere ◽  
Passive Margin ◽  
Crustal Material ◽  
Crustal Accretion ◽  
Mantle Dynamics ◽  
Western Tethys ◽  
Mantle Peridotites ◽  
Slow Spreading ◽  
Tethys Ocean ◽  
Basaltic Crust

The Alpine–Apennine ophiolites are lithospheric remnants of the Jurassic Alpine Tethys Ocean. They predominantly consist of exhumed mantle peridotites with lesser gabbroic and basaltic crust and are locally associated with continental crustal material, indicating formation in an environment transitional from an ultra-slow-spreading seafloor to a hyperextended passive margin. These ophiolites represent a unique window into mantle dynamics and crustal accretion in an ultra-slow-spreading extensional environment. Old, pre-Alpine, lithosphere is locally preserved within the mantle sequences: these have been largely modified by reaction with migrating asthenospheric melts. These reactions were active in both the mantle and the crust and have played a key role in creating the heterogeneous oceanic lithosphere in this branch of the Mesozoic Western Tethys.

Coupling surface and mantle dynamics: A novel experimental approach

2015 ◽  
Vol 42 (10) ◽  
pp. 3863-3869 ◽  
Author(s):  
Agnes Kiraly ◽  
Claudio Faccenna ◽  
Francesca Funiciello ◽  
Andrea Sembroni
Keyword(s):  
Experimental Approach ◽  
Mantle Dynamics
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