Long-wavelength character of subducted slabs in the lower mantle

Běhounková, M.; Čı́žková, Hana

doi:10.1016/j.epsl.2008.07.059

Cited by 59 publications

(47 citation statements)

References 57 publications

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“…The exothermic phase transition expected at ~410 km depth when olivine transforms to its wadsleyite phase can encourage penetration, because it enhances slab sinking and piling in the transition zone (Christensen, 1996;Čížková et al, 2002;Běhounková and Čížková, 2008). However, even with the effect of such an exothermic 410, slabs that can induce trench retreat can still get stalled by G as low as -1 MPa/K (Agrusta et al, 2017).…”

Section: Endothermic Phase Transitionmentioning

confidence: 94%

“…Several studies have estimated that some slabs, e.g., the Cocos, Java, and Hellenic slabs, thicken by a factor of 4-5 upon entering into the lower mantle, to widths of ~400 km (Ribe et al, 2007;Loiselet et al, 2010), or even 400-700 km for the slabs below North America (Sigloch and Mihalynuk, 2013); while thickening in the lower-mantle slab anomalies below the Indian plate has been estimated to be about a factor of 3 (Hafkenscheid et al, 2006). Such strong thickening has commonly been attributed to slab buckling that starts in the transition zone (Ribe et al, 2007;Běhounková and Čížková, 2008;Lee and King, 2011). Thickening has been inferred to be less for some of the older penetrating slabs below the western Pacific (Marianas, Kermadec, Loiselet et al, 2010) but may still be a factor of two, an amount which can also be achieved by simple compressional thickening (Gurnis and Hager, 1988;Běhounková and Čížková, 2008).…”

Section: Seismic Tomography: Lower-mantle Slabsmentioning

confidence: 99%

“…Such strong thickening has commonly been attributed to slab buckling that starts in the transition zone (Ribe et al, 2007;Běhounková and Čížková, 2008;Lee and King, 2011). Thickening has been inferred to be less for some of the older penetrating slabs below the western Pacific (Marianas, Kermadec, Loiselet et al, 2010) but may still be a factor of two, an amount which can also be achieved by simple compressional thickening (Gurnis and Hager, 1988;Běhounková and Čížková, 2008).…”

Section: Seismic Tomography: Lower-mantle Slabsmentioning

confidence: 99%

“…6). At the high end of the geoid and rebound-based viscosity jumps-a factor of 100 or higher-slab sinking into the lower mantle is strongly impeded (Běhounková and Čížková, 2008;Loiselet et al, 2010), trench retreat decreased (Čížková and Bina, 2013;Garel et al, 2014), and the range of slab morphologies is limited to flattening and folding, even if slab cores are 2-3 orders of magnitude more viscous than the surrounding mantle (Garel et al, 2014).…”

Section: Viscosity Jumpmentioning

confidence: 99%

“…In some cases, the upper plate may provide an additional driving force Arcay et al, 2008;Van Dinther et al, 2010;Čížková and Bina, 2015). Stronger plate coupling limits trench mobility and can, when high enough, even preclude subduction (De Franco et al, 2006;Běhounková and Čížková, 2008;Androvičová et al, 2013) (Fig. 8).…”

Section: Role Of Upper Plate and Mantle Resistance: External Controlsmentioning

confidence: 99%

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Subduction-transition zone interaction: A review

et al. 2017

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTAs subducting plates reach the base of the upper mantle, some appear to flatten and stagnate, while others seemingly go through unimpeded. This variable resistance to slab sinking has been proposed to affect long-term thermal and chemical mantle circulation. A review of observational constraints and dynamic models highlights that neither the increase in viscosity between upper and lower mantle (likely by a factor 20-50) nor the coincident endothermic phase transition in the main mantle silicates (with a likely Clapeyron slope of -1 to -2 MPa/K) suffice to stagnate slabs. However, together the two provide enough resistance to temporarily stagnate subducting plates, if they subduct accompanied by significant trench retreat. Older, stronger plates are more capable of inducing trench retreat, explaining why backarc spreading and flat slabs tend to be associated with old-plate subduction. Slab viscosities that are ~2 orders of magnitude higher than background mantle (effective yield stresses of 100-300 MPa) lead to similar styles of deformation as those revealed by seismic tomography and slab earthquakes. None of the current transition-zone slabs seem to have stagnated there more than 60 m.y. Since modeled slab destabilization takes more than 100 m.y., lower-mantle entry is apparently usually triggered (e.g., by changes in plate buoyancy). Many of the complex morphologies of lower-mantle slabs can be the result of sinking and subsequent deformation of originally stagnated slabs, which can retain flat morphologies in the top of the lower mantle, fold as they sink deeper, and eventually form bulky shapes in the deep mantle.

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Section: Endothermic Phase Transitionmentioning

confidence: 94%

Section: Seismic Tomography: Lower-mantle Slabsmentioning

confidence: 99%

Section: Seismic Tomography: Lower-mantle Slabsmentioning

confidence: 99%

Section: Viscosity Jumpmentioning

confidence: 99%

Section: Role Of Upper Plate and Mantle Resistance: External Controlsmentioning

confidence: 99%

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Subduction-transition zone interaction: A review

et al. 2017

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Interaction of subducted slabs with the mantle transition‐zone: A regime diagram from 2‐D thermo‐mechanical models with a mobile trench and an overriding plate

Garel

Goes

Davies

et al. 2014

Geochem Geophys Geosyst

184

294

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Transition zone slab deformation influences Earth's thermal, chemical, and tectonic evolution.However, the mechanisms responsible for the wide range of imaged slab morphologies remain debated. Here we use 2-D thermo-mechanical models with a mobile trench, an overriding plate, a temperature and stress-dependent rheology, and a 10, 30, or 100-fold increase in lower mantle viscosity, to investigate the effect of initial subducting and overriding-plate ages on slab-transition zone interaction. Four subduction styles emerge: (i) a ''vertical folding'' mode, with a quasi-stationary trench, near-vertical subduction, and buckling/folding at depth (VF); (ii) slabs that induce mild trench retreat, which are flattened/''horizontally deflected'' and stagnate at the upper-lower mantle interface (HD); (iii) inclined slabs, which result from rapid sinking and strong trench retreat (ISR); (iv) a two-stage mode, displaying backward-bent and subsequently inclined slabs, with late trench retreat (BIR). Transitions from regime (i) to (iii) occur with increasing subducting plate age (i.e., buoyancy and strength). Regime (iv) develops for old (strong) subducting and overriding plates. We find that the interplay between trench motion and slab deformation at depth dictates the subduction style, both being controlled by slab strength, which is consistent with predictions from previous compositional subduction models. However, due to feedbacks between deformation, sinking rate, temperature, and slab strength, the subducting plate buoyancy, overriding plate strength, and upper-lower mantle viscosity jump are also important controls in thermo-mechanical subduction. For intermediate upper-lower mantle viscosity jumps (330), our regimes reproduce the diverse range of seismically imaged slab morphologies.

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Overriding plate thickness control on subducting plate curvature

Holt

Buffett

Becker

2015

Geophysical Research Letters

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Subducting plate (SP) curvature exerts a key control on the amount of bending dissipation associated with subduction, and the magnitude of the subduction‐resisting bending force. However, the factors controlling the development of SP curvature are not well understood. We use numerical models to quantify the role of SP rheology on the minimum radius of curvature, Rmin. We find that Rmin depends strongly on the SP thickness when the rheology is viscous. This dependence is substantially reduced when the SP behaves plastically, in line with the lack of correlation between Rmin and SP thickness on Earth. In contrast, plasticity leads to a strong positive correlation between Rmin and the overriding plate (OP) thickness. Using an analysis of Rmin versus OP thickness, we show that such a positive correlation exists on Earth. This suggests that OP structure, in conjunction with SP plasticity, is crucial in generating slab curvature systematics on Earth.

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Long-wavelength character of subducted slabs in the lower mantle

Cited by 59 publications

References 57 publications

Subduction-transition zone interaction: A review

Subduction-transition zone interaction: A review

Interaction of subducted slabs with the mantle transition‐zone: A regime diagram from 2‐D thermo‐mechanical models with a mobile trench and an overriding plate

Overriding plate thickness control on subducting plate curvature

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