Trench migration and subduction zone geometry

Olbertz, D.C.; Wortel, M. J. R.; Hansen, Ulrich

doi:10.1029/96gl03971

Cited by 71 publications

(51 citation statements)

References 23 publications

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“…Regional models, of a single subduction system, do generate a range of slab morphologies in response to such a viscosity increase but only if the trench can move freely (Kincaid and Olson, 1987;Gurnis and Hager, 1988;Guillou-Frottier et al, 1995;Christensen, 1996;Olbertz et al, 1997;Garel et al, 2014). The regional-model slab morphologies resemble the diversity of geometries imaged tomo graphically (Fig.…”

Section: Viscosity Jumpmentioning

confidence: 99%

“…Zhong and Gurnis's (1995) model that incorporates mobile plate boundaries clearly established that trench migration can produce slabs that stagnate over significant distances in the transition zone. Many other, regional-scale models prescribed trench motions and determined how much motion is required for flattening (Griffiths et al, 1995;Guillou-Frottier et al, 1995;Christensen, 1996;Olbertz et al, 1997;Čížková et al, 2002;Torii and Yoshioka, 2007). In this way, they inferred critical trench motions or dips.…”

Section: Role Of Trench Motionmentioning

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: Viscosity Jumpmentioning

confidence: 99%

Section: Role Of Trench Motionmentioning

confidence: 99%

Subduction-transition zone interaction: A review

et al. 2017

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“…The slab pull force, F sp , which results from the negative buoyancy of the subducting lithosphere compared to the asthenospheric mantle was thought to control the dynamics of the subduction system and thereby the geometry of the subducted slab and strain regime in the overriding plate (Uyeda & Kanamori 1979). However, modelling studies have shown that the viscous resistance of the mantle also participates in the dynamics of the system (Griffiths et al 1995;Guillou-Frottier et al 1995;Olbertz et al 1997;Royden & Husson 2006). Old and dense subducting slabs are not systematically steeper than young and less dense slabs but generate more backarc opening and/or subduct faster (Schellart 2004a(Schellart , 2005Royden & Husson 2006).…”

Section: Introductionmentioning

confidence: 99%

“…One possible explanation for this observation is that the motion of the upper plate and anchorage of the slab in the mantle are responsible for the shallow geometry of the slab and shortening of the backarc area (Griffiths et al 1995;Guillou-Frottier et al 1995;Scholtz & Campos 1995). Flow in the mantle has been shown to influence the slab geometry (Olbertz et al 1997;Winder & Peacock 2001). 1a), which should promote a steep slab geometry and backarc extension.…”

Section: Introductionmentioning

confidence: 99%

Impact of regional mantle flow on subducting plate geometry and interplate stress: insights from physical modelling

Boutelier¹,

Cruden²

2008

Geophysical Journal International

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SUMMARY Physical models of subduction investigate the impact of regional mantle flow on the structure of the subducted slab and deformation of the downgoing and overriding plates. The initial mantle flow direction beneath the overriding plate can be horizontal or vertical, depending on its location with respect to the asthenospheric flow field. Imposed mantle flow produces either over or underpressure on the lower surface of the slab depending on the initial mantle flow pattern (horizontal or vertical, respectively). Overpressure promotes shallow dip subduction while underpressure tends to steepen the slab. Horizontal mantle flow with rates of 1–10 cm yr−1 provides sufficient overpressure on a dense subducting lithosphere to obtain a subduction angle of ∼60°, while the same lithospheric slab sinks vertically when no flow is imposed. Vertical drag force (due to downward mantle flow) exerted on a slab can result in steep subduction if the slab is neutrally buoyant but fails to produce steep subduction of buoyant oceanic lithosphere. The strain regime in the overriding plate due to the asthenospheric drag force depends largely on slab geometry. When the slab dip is steeper than the interplate zone, the drag force produces negative additional normal stress on the interplate zone and tensile horizontal stress in the overriding plate. When the slab dip is shallower than the interplate zone, an additional positive normal stress is produced on the interplate zone and the overriding plate experiences additional horizontal compressive stress. However, the impact of the mantle drag force on interplate pressure is small compared to the influence of the slab pull force since these stress variations can only be observed when the slab is dense and interplate pressure is low.

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“…Both laboratory (Bercovici and Mahoney, 1994;Griffiths et al, 1995;Guillou-Frottier et Copy right c The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. al., 1995) and numerical experiments (Davies, 1995;Christensen, 1996;Nakakuki et al, 1997;Olbertz et al, 1997;Steinbach and Yuen, 1997;Cizkova and Cadek, 1997;Brunet and Machetel, 1998) have revealed the complicated dynamics in the transition zone region, caused by impinging plumes from the lower mantle and by slab interaction due to surface trench migration. Most of the focus has been directed at the endothermic nature of the phase transition at 660 km depth and not much attention has been devoted on the underlying viscosity structure below this depth.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale structures in the transition zone: Dynamical consequences of boundary layer activities

2014

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Recent geophysical evidence from seismology, mineral physics, viscosity inversion shows that the mantle between 400 and 1000 km is extremely complicated, with intermediate scale structures present regionally as seismic reflectors under the 660 km discontinuity and bent plume-like structures under the transition zone. We have studied the dynamics of the transition zone with two models, an axisymmetric spherical-shell (2-D) model with a horizontally averaged temperature-and pressure-dependent viscosity and a 3-D Cartesian model with a depth-dependent viscosity. Two mantle phase transitions have been employed in both models. Results of the 2-D axisymmetric model show that the interaction of the lower mantle plumes with the transition zone can result in a horizontal channel flow right underneath the 660 km and in the birth of secondary plume some distance away from the lower mantle plume. The strength of the secondary plume increases in strength with larger viscosity contrast across the 660 km discontinuity. In the 3-D model we have found that with the presence of a second low viscosity zone somewhere between 660 and 1000 km, many secondary instabilities are developed in the second asthenosphere and the mesoscale thermal structure developed can become quite complex. Many small-scale plumes can emanate from the transition zone. Occasionally a very large plume burst, with a near-surface radius exceeding 1000 km, can develop from the hot lower-mantle material trapped in the second asthenosphere. Both the viscosity and the phase transition structure between 660 km and 1000 km can exert a significant influence on the plume distribution and cause singular plume eruption events in the upper mantle. Plume instabilities originating below the 660 km discontinuity in the western Pacific might have launched a large hot upwelling into the upper mantle, thus precipitating the massive flood basalt volcanism in the Ontong-Java region.

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Trench migration and subduction zone geometry

Cited by 71 publications

References 23 publications

Subduction-transition zone interaction: A review

Subduction-transition zone interaction: A review

Impact of regional mantle flow on subducting plate geometry and interplate stress: insights from physical modelling

Mesoscale structures in the transition zone: Dynamical consequences of boundary layer activities

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