Reconciling surface plate motions with rapid three-dimensional mantle flow around a slab edge

Nature ◽  
2010 ◽  
Vol 465 (7296) ◽  
pp. 338-341 ◽  
Author(s):  
Margarete A. Jadamec ◽  
Magali I. Billen
Keyword(s):  
Three Dimensional ◽  
Mantle Flow ◽  
Plate Motions ◽  
Surface Plate

scholarly journals The influence of plate motions on three-dimensional back arc mantle flow and shear wave splitting

2000 ◽  
Vol 105 (B12) ◽  
pp. 28009-28033 ◽  
Author(s):  
Chad E. Hall ◽  
Karen M. Fischer ◽  
E. M. Parmentier ◽  
Donna K. Blackman
Keyword(s):  
Shear Wave ◽  
Three Dimensional ◽  
Shear Wave Splitting ◽  
Mantle Flow ◽  
Plate Motions ◽  
Wave Splitting ◽  
Back Arc

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 Antarctic Upper Mantle Rheology

2021 ◽  
pp. M56-2020-19
Author(s):  
E. R. Ivins ◽  
W. van der Wal ◽  
D. A. Wiens ◽  
A. J. Lloyd ◽  
L. Caron
Keyword(s):  
Wave Velocity ◽  
Upper Mantle ◽  
Effective Viscosity ◽  
Seismic Velocity ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Velocity Model ◽  
Mantle Flow ◽  
S Wave ◽  
Velocity Changes

AbstractThe Antarctic mantle and lithosphere are known to have large lateral contrasts in seismic velocity and tectonic history. These contrasts suggest differences in the response time scale of mantle flow across the continent, similar to those documented between the northeastern and southwestern upper mantle of North America. Glacial isostatic adjustment and geodynamical modeling rely on independent estimates of lateral variability in effective viscosity. Recent improvements in imaging techniques and the distribution of seismic stations now allow resolution of both lateral and vertical variability of seismic velocity, making detailed inferences about lateral viscosity variations possible. Geodetic and paleo sea-level investigations of Antarctica provide quantitative ways of independently assessing the three-dimensional mantle viscosity structure. While observational and causal connections between inferred lateral viscosity variability and seismic velocity changes are qualitatively reconciled, significant improvements in the quantitative relations between effective viscosity anomalies and those imaged by P- and S-wave tomography have remained elusive. Here we describe several methods for estimating effective viscosity from S-wave velocity. We then present and compare maps of the viscosity variability beneath Antarctica based on the recent S-wave velocity model ANT-20 using three different approaches.

An analytical model concerning the possible initiation of subduction between the India and Africa plates, caused by the Morondova plume

2020 ◽  
Author(s):  
Bernhard Steinberger ◽  
Douwe van Hinsbergen
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Eastern Mediterranean ◽  
Plate Boundary ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Motions ◽  
Subduction Initiation ◽  
Euler Pole ◽  
Geodynamic Processes

<p>Identifying the geodynamic processes that trigger the formation of new subduction zones is key to understand what keeps the plate tectonic cycle going, and how plate tectonics once started. Here we discuss the possibility of plume-induced subduction initiation. Previously, our numerical modeling revealed that mantle upwelling and radial push induced by plume rise may trigger plate motion change, and plate divergence as much as 15-20 My prior to LIP eruption. Here we show that, depending on the geometry of plates, the distribution of cratonic keels and where the plume rises, it may also cause a plate rotation around a pole that is located close to the same plate boundary where the plume head impinges: If that occurs near one end of the plate boundary, an Euler pole of the rotation may form along that plate boundary, with extension on one side, and convergence on the other.  This concept is applied to the India-Africa plate boundary and the Morondova plume, which erupted around 90 Ma, but may have influenced plate motions as early as 105-110 Ma. If there is negligible friction, i.e. there is a pre-existing weak plate boundary, we estimate that the total amount of convergence generated in the northern part of the India-Africa plate boundary can exceed 100 km, which is widely thought to be sufficient to initiate forced, self-sustaining subduction. This may especially occur if the India continental craton acts like an “anchor” causing a comparatively southern location of the rotation pole of the India plate. Geology and paleomagnetism-based reconstructions of subduction initiation below ophiolites from Pakistan, through Oman, to the eastern Mediterranean reveal that E-W convergence around 105 Ma caused forced subduction initiation, and we tentatively postulate that this is triggered by Morondova plume head rise. Whether the timing of this convergence is appropriate to match observations on subduction initiation as early as 105 Ma depends on the timing of plume head arrival, which may predate eruption of the earliest volcanics. It also depends on whether a plume head already can exert substantial torque on the plate while it is still rising – for example, if the plate is coupled to the induced mantle flow by a thick craton.</p>

Seismological evidence of mantle flow driving plate motions at a palaeo-spreading centre

2014 ◽  
Vol 7 (5) ◽  
pp. 371-375 ◽  
Author(s):  
Shuichi Kodaira ◽  
Gou Fujie ◽  
Mikiya Yamashita ◽  
Takeshi Sato ◽  
Tsutomu Takahashi ◽  
...  
Keyword(s):  
Mantle Flow ◽  
Plate Motions

Hull Plate Bending Springback Prediction Based on Artificial Neural Network

2014 ◽  
Vol 988 ◽  
pp. 309-312
Author(s):  
Shao Juan Su ◽  
Yong Hu ◽  
Cheng Fang Wang ◽  
Bin Liu
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Three Dimensional ◽  
Plate Bending ◽  
Forming Process ◽  
Cold Bending ◽  
Matlab Programming ◽  
Springback Prediction ◽  
Surface Plate

In the process of three-dimensional curved hull plate forming, springback caused serious influence on the forming accuracy, in order to ensure the forming quality of the asymmetric multiple pressure heads CNC bending machine of ship hull 3D surface plate, to achieve the automatic processing, it is necessary to solve the problem of springback in the hull plate forming process. It is rarely to see the research on the cold bending springback problem of middle-thickness hull plate now. To established nonlinear model of plate parameters and springback amount based on BP neural network, accurately analyzing the prediction of springback, and getting the sptringback prediction model based on the BP neural network in the Matlab programming.

scholarly journals The dynamics of laterally variable subductions: laboratory models applied to the Hellenides

2013 ◽  
Vol 5 (1) ◽  
pp. 315-363 ◽  
Author(s):  
B. Guillaume ◽  
L. Husson ◽  
F. Funiciello ◽  
C. Faccenna
Keyword(s):  
Three Dimensional ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Plate Deformation ◽  
The North ◽  
North Aegean ◽  
Dextral Shear ◽  
Tear Fault ◽  
Negatively Buoyant ◽  
Laboratory Models

Abstract. We design three-dimensional dynamically self-consistent laboratory models of subduction to analyze the relationships between overriding plate deformation and subduction dynamics in the upper mantle. We investigate the effects of the subduction of a lithosphere of laterally variable buoyancy on the temporal evolution of trench kinematics and shape, horizontal flow at the top of the asthenosphere, dynamic topography and deformation of the overriding plate. The interface between the two units, analogue to a trench-perpendicular tear fault between a negatively buoyant oceanic plate and positively buoyant continental one, is either fully-coupled or shear-stress free. Differential rates of trench retreat, in excess of 6 cm yr−1 between the two units, trigger a more vigorous mantle flow above the oceanic slab unit than above the continental slab unit. The resulting asymmetrical sublithospheric flow shears the overriding plate in front of the tear fault, and deformation gradually switches from extension to transtension through time. The consistency between our models results and geological observations suggests that the Late Cenozoic deformation of the Aegean domain, including the formation of the North Aegean Trough and Central Hellenic Shear zone, results from the spatial variations in the buoyancy of the subducting lithosphere. In particular, the lateral changes of the subduction regime caused by the Early Pliocene subduction of the old oceanic Ionian plate redesigned mantle flow and excited an increasingly vigorous dextral shear underneath the overriding plate. The models suggest that it is the inception of the Kefalonia Fault that caused the transition between an extension dominated tectonic regime to transtension, in the North Aegean, Mainland Greece and Peloponnese. The subduction of the tear fault may also have helped the propagation of the North Anatolian Fault into the Aegean domain.

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