Rheology of the upper mantle and the mantle wedge: A view from the experimentalists

Hirth, Greg; Kohlstedt, D. L.

doi:10.1029/138gm06

Cited by 1,160 publications

(1,893 citation statements)

References 79 publications

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“…The above result is puzzling because the dependence of mantle viscosity on water content is reasonably wellcharacterized [Hirth and Kohlstedt, 1996;Hirth and Kohlstaedt, 2003] and has been shown to be important in explaining analogous observations at the Iceland hotspot-ridge system [Ito et al, 1999;Bianco et al, 2013]. A possible explanation for this apparent contradiction comes from considering the strain-rate dependence of mantle rheology.…”

Section: The Case For a Low-viscosity Galápagos Plumementioning

confidence: 98%

“…Activation energy (E = 250 kJ/mol) and activation volume (V = 6 × 10 -6 m 3 /mol) are reduced relative to laboratory-constrained values [Hirth and Kohlstaedt, 2003] for dislocation creep so that the above Newtonian rheological parameterization approximates the behavior of a power law (i.e., strain-rate-dependent) rheology [Christensen, 1984].…”

Section: Mantle Convectionmentioning

confidence: 99%

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Patterns in Galápagos Magmatism Arising from the Upper Mantle Dynamics of Plume‐Ridge Interaction

Ito

Bianco

2014

The Galápagos

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Section: The Case For a Low-viscosity Galápagos Plumementioning

confidence: 98%

Section: Mantle Convectionmentioning

confidence: 99%

Patterns in Galápagos Magmatism Arising from the Upper Mantle Dynamics of Plume‐Ridge Interaction

Ito

Bianco

2014

The Galápagos

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“…In addition, the rheology of the lithospheric mantle is stratified owing to differences in water content that results from the melting processes at mid-ocean ridges [Braun et al, 2000]. Beneath the lithosphere, as temperature increases with depth, thermally activated deformation mechanisms such as diffusion creep (Newtonian viscosity) and dislocation creep (non-Newtonian, stressdependent viscosity) accommodate deformation [Karato and Wu, 1993;Karato and Jung, 2003;Hirth and Kohlstedt, 2003]. …”

Section: Rheology Of the Mantle And Subducting Slabsmentioning

confidence: 99%

Rheologic controls on slab dynamics

Billen

Hirth

2007

Geochem Geophys Geosyst

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205

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[1] Several models have been proposed to relate slab geometry to parameters such as plate velocity or plate age. However, studies on the observed relationships between slab geometry and a wide range of subduction parameters show that there is not a simple global relationship between slab geometry and any one of these other subduction parameters for all subduction zones. Numerical and laboratory models of subduction provide a method to explore the relative importance of different physical processes in determining subduction dynamics. Employing 2-D numerical models with a viscosity structure constrained by laboratory experiments for the deformation of olivine, we show that the observed range in slab dip and the observed trends between slab dip and convergence velocity, subducting plate age, and subduction duration can be reproduced without trench motion (i.e., slab roll-back) for locations away from slab edges. Successful models include a stiff slab that is 100-1000 times more viscous than previous estimates from models of plate bending, the geoid, and global plate motions. We find that slab dip in the upper mantle depends primarily on slab strength and plate boundary coupling, with a small dependence on subducting plate age. Once the slab sinks into the lower mantle the primary processes controlling slab evolution are (1) the ability of the stiff slab to transmit stresses up dip, (2) resistance to slab descent into the higherviscosity lower mantle, and (3) subduction-induced flow in the mantle-wedge corner.

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“…Recent observations on natural samples highlighted the importance of the grain-size-dependent dislocation-accommodated grain boundary sliding (disGBS) of olivine as controlling the rheology of mantle shear zone (Précigout et al, 2007;Warren and Hirth, 2006). Deformation experiments and numerical investigations have also shown that disGBS could promote strain localisation during dynamic recrystallization (Hirth and Kohlstedt, 2003;Précigout and Gueydan, 2009). Indeed, under conditions where disGBS constitutes the dominant deformation mechanism of peridotite, i.e., at temperature lower than 800°C, grain size reduction is associated with a significant drop of strength ( (Précigout et al, 2007), see Appendix for more details).…”

Section: / Geological Constraintsmentioning

confidence: 99%

“…Based on field observations in the Ronda peridotite (southern Spain) and the experimental data of Hirth and Kohlstedt (2003), Précigout et al (2007) proposed a strain-dependent mantle rheology in which the overall strain rate ̇ is the sum of four ductile deformation mechanisms: dislocation creep ( ̇), diffusion creep ( ̇), disGBS ( ̇) and exponential creep ( ̇) (Hirth and Kohlstedt, 2003;Drury, 2005;Précigout et al, 2007). Each mechanism contributes to the bulk strain rate ( ) of an olivine aggregate according to:…”

Section: / Mantle Rheologymentioning

confidence: 99%

Strain weakening enables continental plate tectonics

2014

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Much debate exists concerning the strength distribution of the continental lithosphere, how it controls lithosphere-scale strain localization and hence enables plate tectonics. No rheological model proposed to date is comprehensive enough to describe both the weakness of plate boundary and rigid-like behaviour of plate interiors. Here we show that the duality of strength of the lithosphere corresponds to different stages of microstructural evolution. Geological constraints on lithospheric strength and large strain numerical experiments reveal that the development of layers containing weak minerals and the onset of grain boundary sliding upon grain size reduction in olivine cause strain localisation and reduce strength in the crust and subcontinental mantle, respectively. The positive feedback between weakening and strain localization leads to the progressive development of weak plate boundaries while plate interiors remain strong. 2 1/ IntroductionThe extrapolation of laboratory flow laws to geological scale suggests a complex layering of brittle and ductile layers within the continental lithosphere (Brace and Kohlstedt, 1980;Sawyer, 1985). For classical continental geotherm, the upper lithospheric mantle is expected to be brittle and support high stresses. Many analogue and numerical experiments indicate that such a rheological layering is important to reproduce first-order patterns of lithosphere deformation (Brun, 1999;Burov and Yamato, 2008). In particular, the presence of a brittle uppermost mantle is needed to explain strain localisation at lithospheric scale (Buck, 1991;Gueydan et al., 2008).However, recent geophysical studies question this classical view of the continental strength layering. Based on earthquakes distribution and elastic thicknesses of the continental lithosphere, including cratons, it has been proposed that the uppermost mantle could behave as ductile instead of brittle (Déverchère et al., 2001;Jackson, 2002;Maggi et al., 2000). However, the mechanical stability of cratons requires that the uppermost mantle supports high stresses (Burov, 2010). In addition, the post-seismic displacement field, i.e., the pattern of deformation at the surface of the Earth within weeks to years following an earthquake, suggests that the deep crust is stronger than the lithospheric mantle. (Bürgmann and Dresen, 2008;Thatcher and Pollitz, 2008). Note however that post seismic displacement field may also result from a complex combination of poro-elasticity and fault creep in the seismogenic layer and viscous flow in the lower crust (Barbot and Fialko, 2010). In this case, it may not be used to constrain strength ratios between the ductile crust 3 and lithospheric mantle. Finally, the recent discovery of non-volcanic tremors, i.e., long duration seismic events with small amplitudes, below the San Andreas fault suggests a zone of localized and easily modulated faulting in the lower crust (Nadeau and Guilhem, 2009;Thomas et al., 2009). Assuming high temperatures in plate boundaries such as the San Andreas...

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Rheology of the upper mantle and the mantle wedge: A view from the experimentalists

Cited by 1,160 publications

References 79 publications

Patterns in Galápagos Magmatism Arising from the Upper Mantle Dynamics of Plume‐Ridge Interaction

Patterns in Galápagos Magmatism Arising from the Upper Mantle Dynamics of Plume‐Ridge Interaction

Rheologic controls on slab dynamics

Strain weakening enables continental plate tectonics

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