Upper-mantle dynamics revealed by helium isotope variations along the southeast Indian ridge

Nature ◽  
2001 ◽  
Vol 409 (6821) ◽  
pp. 701-703 ◽  
Author(s):  
D. W. Graham ◽  
J. E. Lupton ◽  
F. J. Spera ◽  
D. M. Christie
Keyword(s):  
Upper Mantle ◽  
Helium Isotope ◽  
Mantle Dynamics ◽  
Southeast Indian Ridge ◽  
Indian Ridge

Contrasting origins of the upper mantle revealed by hafnium and lead isotopes from the Southeast Indian Ridge

Nature ◽  
2004 ◽  
Vol 432 (7013) ◽  
pp. 91-94 ◽  
Author(s):  
Barry B. Hanan ◽  
Janne Blichert-Toft ◽  
Douglas G. Pyle ◽  
David M. Christie
Keyword(s):  
Upper Mantle ◽  
Lead Isotopes ◽  
Southeast Indian Ridge ◽  
Indian Ridge

scholarly journals Erratum: Corrigendum: Contrasting origins of the upper mantle revealed by hafnium and lead isotopes from the Southeast Indian Ridge

Nature ◽  
2004 ◽  
Vol 432 (7017) ◽  
pp. 653-653
Author(s):  
Barry B. Hanan ◽  
Janne Blichert-Toft ◽  
Douglas G. Pyle ◽  
David M. Christie
Keyword(s):  
Upper Mantle ◽  
Lead Isotopes ◽  
Southeast Indian Ridge ◽  
Indian Ridge

Pb and Hf isotope variations along the Southeast Indian Ridge and the dynamic distribution of MORB source domains in the upper mantle

2013 ◽  
Vol 375 ◽  
pp. 196-208 ◽  
Author(s):  
Barry B. Hanan ◽  
Janne Blichert-Toft ◽  
Christophe Hemond ◽  
Kaan Sayit ◽  
Arnaud Agranier ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Hf Isotope ◽  
Dynamic Distribution ◽  
Southeast Indian Ridge ◽  
Morb Source ◽  
Indian Ridge

scholarly journals Cryptic striations in the upper mantle revealed by hafnium isotopes in southeast Indian ridge basalts

Nature ◽  
2006 ◽  
Vol 440 (7081) ◽  
pp. 199-202 ◽  
Author(s):  
D. W. Graham ◽  
J. Blichert-Toft ◽  
C. J. Russo ◽  
K. H. Rubin ◽  
F. Albarède
Keyword(s):  
Upper Mantle ◽  
Hafnium Isotopes ◽  
Southeast Indian Ridge ◽  
Indian Ridge

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.

scholarly journals Mantle-derived helium released through the Japan trench bend-faults

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jin-Oh Park ◽  
Naoto Takahata ◽  
Ehsan Jamali Hondori ◽  
Asuka Yamaguchi ◽  
Takanori Kagoshima ◽  
...  
Keyword(s):  
Upper Mantle ◽  
Large Scale ◽  
Japan Trench ◽  
Helium Isotope ◽  
Normal Faults ◽  
Circulation System ◽  
Deep Penetration ◽  
Oceanic Plate ◽  
Seismic Reflection Data ◽  
Reflection Data

AbstractPlate bending-related normal faults (i.e. bend-faults) develop at the outer trench-slope of the oceanic plate incoming into the subduction zone. Numerous geophysical studies and numerical simulations suggest that bend-faults play a key role by providing pathways for seawater to flow into the oceanic crust and the upper mantle, thereby promoting hydration of the oceanic plate. However, deep penetration of seawater along bend-faults remains controversial because fluids that have percolated down into the mantle are difficult to detect. This report presents anomalously high helium isotope (3He/4He) ratios in sediment pore water and seismic reflection data which suggest fluid infiltration into the upper mantle and subsequent outflow through bend-faults across the outer slope of the Japan trench. The 3He/4He and 4He/20Ne ratios at sites near-trench bend-faults, which are close to the isotopic ratios of bottom seawater, are almost constant with depth, supporting local seawater inflow. Our findings provide the first reported evidence for a potentially large-scale active hydrothermal circulation system through bend-faults across the Moho (crust-mantle boundary) in and out of the oceanic lithospheric mantle.

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