Shear heating induced lithospheric-scale localization: Does it result in subduction?

Thielmann, Marcel; Kaus, Boris

doi:10.1016/j.epsl.2012.10.002

Cited by 134 publications

(108 citation statements)

References 62 publications

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“…Although the elastic response of the lithosphere and mantle can be ignored over long times (>1 million years), elasticity might play an important role in subduction initiation (e.g. Hall et al 2003;Regenauer-Lieb et al 2001;Thielmann and Kaus 2012;Toth and Gurnis 1998). Mechanisms like the interaction of thermo-chemical plumes with the lithosphere (Burov and Cloetingh 2010;Burov and Gerya 2014;Ueda et al 2008) or small-scale convection in the sub-lithospheric mantle (Solomatov 2004) might further be able to break an intact lid.…”

Section: Introductionmentioning

confidence: 99%

“…Different weakening mechanisms like the addition of water or melt into the lithosphere (Dymkova and Gerya 2013;Hirth and Kohlstedt 2003), grain-size reduction (e.g. Bercovici and Ricard 2005Karato et al 1980Karato et al , 1986Rozel et al 2011), void generation (Bercovici 1998;RegenauerLieb 1998) or shear-heating (Crameri and Kaus 2010;Lu et al 2015;Thielmann and Kaus 2012;Yuen et al 1978) have been proposed to be a key in subduction initiation by providing a necessary weak and localised, lithosphericscale shear zone. Although the elastic response of the lithosphere and mantle can be ignored over long times (>1 million years), elasticity might play an important role in subduction initiation (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface

Crameri

Tackley

2016

Prog. in Earth and Planet. Sci.

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Subduction initiation is a key in understanding the dynamic evolution of the Earth and its fundamental difference to all other rocky planetary bodies in our solar system. Despite recent progress, the question about how a stiff, mostly stagnant planetary lid can break and become part in the global overturn of the mantle is still unresolved. Many mechanisms, externally or internally driven, are proposed in previous studies. Here, we present the results on subduction initiation obtained by dynamically self-consistent, time-dependent numerical modelling of mantle convection. We show that the stress distribution and resulting deformation of the lithosphere are strongly controlled by the top boundary formulation: A free surface enables surface topography and plate bending, increases gravitational sliding of the plates and leads to more realistic, lithosphere-scale shear zones. As a consequence, subduction initiation induced by regional mantle flow is demonstrably favoured by a free surface compared to the commonly applied, vertically fixed (i.e. free-slip) surface. In addition, we present global, three-dimensional mantle convection experiments that employ basal heating that leads to narrow mantle plumes. Narrow mantle plumes impinging on the base of the plate cause locally weak plate segments and a large topography at the lithosphere-asthenosphere boundary. Both are shown to be key to induce subduction initiation. Finally, our model self-consistently reproduces an episodic lid with a fast global overturn due to the hotter mantle developed below a former stagnant lid. We conclude that once in a stagnant-lid mode, a planet (like Venus) might preferentially evolve by temporally discrete, global overturn events rather than by a continuous recycling of lid and that this is something worth testing more rigorously in future studies.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface

Crameri

Tackley

2016

Prog. in Earth and Planet. Sci.

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“…Other weakening processes are expected in the deep crust, such as shear heating (Thielmann and Kaus, 2012), but are disregard here in order to focus on strain weakening related to microstructural evolution.…”

Section: / Geological Constraintsmentioning

confidence: 99%

“…A new definition of the continental lithosphere strength is needed to reconcile the apparent contradiction between 1) the mechanical prerequisite of a strong brittle mantle to trigger lithosphere-scale strain localisation, and 2) the low lithosphere strength inferred in actively deforming region, especially in the mantle. Although it may be argued that the presence of fluid and/or shear heating can trigger weak plate boundaries (Jackson, 2002;Thielmann and Kaus, 2012), the existence of long-lived lithosphere-scale inherited weak zone (Tommasi et al, 2009) suggests that a structural origin for the weakness of plate boundaries is also necessary. Crucially, lithospheric strength must decrease with increasing strain.…”

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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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“…Additional heat can be supplied by shear heating, affecting the thermal state of subduction zones and, thus, the rheology of the system (e.g. Gerya & Yuen 2003;Burg & Gerya 2005;Gerya & Stoeckhert 2006;Gerya et al 2008;Hartz & Podladchikov 2008;Thielmann & Kaus 2012;Minakov et al 2013;Souche et al 2013).…”

Section: Introductionmentioning

confidence: 99%

2-D numerical study of hydrated wedge dynamics from subduction to post-collisional phases

Regorda¹,

Roda²,

Marotta³

et al. 2017

Geophysical Journal International

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S U M M A R YWe developed a 2-D finite element model to investigate the effect of shear heating and mantle hydration on the dynamics of the mantle wedge area. The model considers an initial phase of active oceanic subduction, which is followed by a post-collisional phase characterized by pure gravitational evolution. To investigate the impact of the subduction velocity on the thermomechanics of the system, three models with different velocities prescribed during the initial subduction phase were implemented. Shear heating and mantle hydration were then systematically added into the models. We then analysed the evolution of the hydrated area during both the subduction and post-collisional phases, and examined the difference in P max -T (maximum pressure-temperature) and P-T max (pressure-maximum temperature) conditions for the models with mantle hydration. The dynamics that allow for the recycling and exhumation of subducted material in the wedge area are strictly correlated with the thermal state at the external boundaries of the mantle wedge, and the size of the hydrated area depends on the subduction velocity when mantle hydration and shear heating are considered simultaneously. During the post-collisional phase, the hydrated portion of the mantle wedge increases in models with high subduction velocities. The predicted P-T configuration indicates that contrasting P-T conditions, such as Barrovian-to Franciscan-type metamorphic gradients, can contemporaneously characterize different portions of the subduction system during both the active oceanic subduction and post-collisional phases and are not indicative of collisional or subduction phases.

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Shear heating induced lithospheric-scale localization: Does it result in subduction?

Cited by 134 publications

References 62 publications

Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface

Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface

Strain weakening enables continental plate tectonics

2-D numerical study of hydrated wedge dynamics from subduction to post-collisional phases

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