The effects of phase transitions and compositional layering in two-dimensional kinematic models of subduction

Arredondo, K.; Billen, M. I.

doi:10.1016/j.jog.2016.05.009

Cited by 40 publications

(43 citation statements)

References 90 publications

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“…However, because there is only a moderate jump in viscosity between the upper and lower mantle, there is no folding or buckling of the slab [ Ribe et al , ; Lee and King , ]. This behavior is the same as that found for similar models run with kinematic surface boundary conditions [ Arredondo and Billen , ].…”

Section: Resultscontrasting

confidence: 99%

“…The suite of models explored in this study demonstrate how the coupled effects of phase transitions and stress‐dependent rheology leads to oscillatory behavior in plate speed and trench motion in response to deformation of the slab in the transition zone. As in our previous study using kinematic boundary conditions [ Arredondo and Billen , ], we find that as the driving stresses change due to the phase transitions, the stress‐dependent rheology causes a reduction in viscosity around the slab. Reduction in the mantle viscosity forces more of the weight of the slab to be supported by the internal strength of the slab causing the slab to weaken and stretch.…”

Section: Discussionmentioning

confidence: 99%

“…We model this phase transition using the albite

\to

jadeite + quartz transition in which the appearance of garnet is primarily controlled by temperature at pressures above 15 to 25 kbar [ Hacker et al , ; Bousquet et al , ; Holland , ]. Therefore, we implement this transition as in previous studies starting at 700°C for pressures above 15 kbar and running to completion by 850°C [ Arrial and Billen , ; Arredondo and Billen , ]. Following the transition to eclogite, pyroxene will dissolve into garnet and then garnet will undergo the same phase transitions as in pyrolite (however, see notes in Table ).…”

Section: Compositionally Dependent Phase Transition Modelmentioning

confidence: 99%

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Coupled effects of phase transitions and rheology in 2‐D dynamical models of subduction

Arredondo

Billen

2017

JGR Solid Earth

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Observations of seismicity and seismic tomography provide a present‐day constraint on the geometry of slabs within the mantle. However, it is challenging to directly relate the observed shape of slabs to their time evolution. Phase transitions modify the buoyancy forces within slabs, affecting how slabs deform as they sink into the lower mantle and how forces are transmitted to the surface plates. Here we show that if the crustal shear zone is sufficiently weak (1020 Pa s), then the coupled effects of a compositionally dependent phase transition model and a stress‐dependent rheology lead to oscillatory plate speeds and trench motion in response to buckling and folding of the slab. On average, subducting plate velocity is 4 cm/yr and trench motion is ±0.7 cm/yr. However, during folding, subducting plate speed and trench motion increases by a factor of 3 and trench motion switches from advance to retreat. In models with a higher‐viscosity shear zone (1021 Pa s), average plate speed is lower (2 cm/yr) and there is only trench advance. Stress‐dependent weakening due to increasing driving stresses can also cause unexpected changes in plate velocity (i.e., decrease or no change). In addition, due to the added negative buoyancy from the phase transitions, slab breakoff occurs in models with a yield stress ≤500 MPa. Because of the oscillatory motion of the trench, long flat slabs do not form in the transition zone: this suggests that other factors, such as interaction of the slab with deep mantle flow, may be required to create long flat slabs.

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Section: Resultscontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…We model this phase transition using the albite

\to

Section: Compositionally Dependent Phase Transition Modelmentioning

confidence: 99%

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Coupled effects of phase transitions and rheology in 2‐D dynamical models of subduction

Arredondo

Billen

2017

JGR Solid Earth

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“…The choice of kinematic conditions can lead to quite different slab stress patterns (Čížková et al, 2007), and it needs to be borne in mind that kinematic forcing may not allow the energetically Goes et al | Subduction-transition zone review GEOSPHERE | Volume 13 | Number 3 most favorable modes of subduction (Han and Gurnis, 1999). In models where the trench is held fixed, higher slab strength is found to encourage penetration (Zhong and Gurnis, 1994;Arredondo and Billen, 2016), contrasting with dynamic trench-motion models where higher slab strength aids trench retreat and slab flattening (e.g., Zhong and Gurnis, 1995;Capitanio et al, 2007).…”

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

confidence: 99%

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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“…The model exhibiting spontaneous arc rifting is the only one in which rifting occurred out of a suite of over 40 models that varied subducting plate age (40 and 80 Ma), crustal viscosity (10 20 –10 21 Pa s), overriding plate age (20 and 40 Ma; with or without ridge push), compositional density (with or without), boundary conditions (kinematic and fully dynamic), and transition zone phase changes (Arredondo, ; Arredondo and Billen, , ). The limited range of conditions in which arc rifting occurs in the models is due to the potentially unstable nature of the high‐viscosity boundary separating the mantle wedge from the weak crustal material.…”

Section: Discussionmentioning

confidence: 99%

Insights Into the Causes of Arc Rifting From 2‐D Dynamic Models of Subduction

Billen

2017

Geophysical Research Letters

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Back-arc spreading centers initiate as fore-arc or arc rifting events when extensional forces localize within lithosphere weakened by hydrous fluids or melting. Two models have been proposed for triggering fore-arc/arc rifting: rollback of the subducting plate causing trench retreat or motion of the overriding plate away from the subduction zone. This paper demonstrates that there is a third mechanism caused by an in situ instability that occurs when the thin high-viscosity boundary, which separates the weak fore arc from the hot buoyant mantle wedge, is removed. Buoyant upwelling mantle causes arc rifting, drives the overriding plate away from the subducting plate, and there is sufficient heating of the subducting plate crust and overriding plate lithosphere to form adakite or boninite volcanism. For spontaneous fore-arc/arc rifting to occur a broad region of weak material must be present and one of the plates must be free to respond to the upwelling forces. Plain Language Summary Oceanic spreading centers are commonly found in the region above sinking plates. These spreading centers are known to form as the result of extension and breaking apart of the arc of volcanoes that form close to where the sinking plate enters the mantle. Here we show that the rifting of a volcanic arc can occur spontaneously and is driven by the buoyancy of the hot mantle wedge material. This result is different from existing models for arc rifting, which argue that external changes in the motion of the sinking or overriding plate are required to cause arc rifting.

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The effects of phase transitions and compositional layering in two-dimensional kinematic models of subduction

Cited by 40 publications

References 90 publications

Coupled effects of phase transitions and rheology in 2‐D dynamical models of subduction

Coupled effects of phase transitions and rheology in 2‐D dynamical models of subduction

Subduction-transition zone interaction: A review

Insights Into the Causes of Arc Rifting From 2‐D Dynamic Models of Subduction

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