Slab surface temperature in subduction zones: Influence of the interplate decoupling depth and upper plate thinning processes

Arcay, Diane; Tric, Emmanuel; Doin, Marie‐Pierre

doi:10.1016/j.epsl.2006.12.027

Cited by 73 publications

(63 citation statements)

References 67 publications

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“…1b). The depth of BDT, z BDT , cannot exceed the interplate decoupling depth, z dec , but some authors have assumed that the kinematic decoupling was occurring at the BDT (Furukawa, 1993;Conder, 2005;Arcay et al, 2007bArcay et al, ,a, 2008. I test this hypothesis in this paper and show that conditions required to simulate z BDT = z dec may be much more restricted than initially expected.…”

Section: Depth Of Interplate Kinematic Decoupling Vs Depth Of Brittlmentioning

confidence: 80%

Dynamics of interplate domain in subduction zones: influence of rheological parameters and subducting plate age

Arcay

2012

Solid Earth

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Abstract. The properties of the subduction interplate domain are likely to affect not only the seismogenic potential of the subduction area but also the overall subduction process, as it influences its viability. Numerical simulations are performed to model the long-term equilibrium state of the subduction interplate when the diving lithosphere interacts with both the overriding plate and the surrounding convective mantle. The thermomechanical model combines a nonNewtonian viscous rheology and a pseudo-brittle rheology. Rock strength here depends on depth, temperature and stress, for both oceanic crust and mantle rocks. I study the evolution through time of, on one hand, the brittle-ductile transition (BDT) depth, z BDT , and, on the other hand, of the kinematic decoupling depth, z dec , simulated along the subduction interplate. The results show that both a high friction and a low ductile strength at the asthenospheric wedge tip shallow z BDT . The influence of the weak material activation energy is of second order but not negligible. z BDT becomes dependent on the ductile strength increase with depth (activation volume) if the BDT occurs at the interplate decoupling depth. Regarding the interplate decoupling depth, it is shallowed (1) significantly if mantle viscosity at asthenospheric wedge tip is low, (2) if the difference in mantle and interplate activation energy is weak, and (3) if the activation volume is increased. Very low friction coefficients and/or low asthenospheric viscosities promote z BDT = z dec . I then present how the subducting lithosphere age affects the brittle-ductile transition depth and the kinematic decoupling depth in this model. Simulations show that a rheological model in which the respective activation energies of mantle and interplate material are too close hinders the mechanical decoupling at the down-dip extent of the interplate, and eventually jams the subduction process during incipient subduction of a young (20-Myr-old) and soft lithosphere under a thick upper plate. Finally, both the BDT depth and the decoupling depth are a function of the subducting plate age, but are not influenced in the same fashion: cool and old subducting plates deepen the BDT but shallow the interplate decoupling depth. Even if BDT and kinematic decoupling are intrinsically related to different mechanisms of deformation, this work shows that they are able to interact closely. Comparison between modelling results and observations suggests a minimum friction coefficient of 0.045 for the interplate plane, even 0.069 in some cases, to model realistic BDT depths. The modelled z dec is a bit deeper than suggested by geophysical observations. Eventually, the better way to improve the adjustment to observations may rely on a moderate to strong asthenosphere viscosity reduction in the metasomatised mantle wedge.

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Section: Depth Of Interplate Kinematic Decoupling Vs Depth Of Brittlmentioning

confidence: 80%

Dynamics of interplate domain in subduction zones: influence of rheological parameters and subducting plate age

Arcay

2012

Solid Earth

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“…The thermal structure of the plate directly above the slab is most important for the slab evolution. While the age of overriding plates varies significantly, the island arc region is thought to have temperatures of 1200-1400°C at depths of 50 km due in part to convective erosion from melt and volatile weakening of the overriding lithosphere [Kelemen et al, 2003;Arcay et al, 2007; A.-M. Cagnioncle et al, The effect of solid flow above a subducting slab on water distribution and melting at convergent plate boundaries, submitted to Journal of Geophysical Research, 2007]. Therefore a warm and thin overriding plate is appropriate and it is assigned an initial thermal structure determined by a half-space cooling model for a 40 my old plate.…”

Section: Model Setupmentioning

confidence: 99%

Rheologic controls on slab dynamics

Billen

Hirth

2007

Geochem Geophys Geosyst

201

186

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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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“…Aside from non-Newtonian effects, which we did not address in this study, these model comparisons should be extended with more realistic wedge descriptions, which include the roles of buoyancy and low viscosity (Billen and Gurnis, 2001) that may lead to additional 3-D flow patterns (e.g., Honda and Yoshida, 2005), dynamic erosion of the overriding plate (Currie and Hyndman, 2006;Arcay et al, 2007), mantle compressibility (Lee and King, 2009) and the effects of fluids and melt on wedge rheology (e.g., Hirth and Kohlstedt, 1996).…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional thermal structure of subduction zones: effects of obliquity and curvature

Bengtson

Keken²

2012

Solid Earth

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Abstract. Quantifying the precise thermal structure of subduction zones is essential for understanding the nature of metamorphic dehydration reactions, arc volcanism, and intermediate depth seismicity. High resolution twodimensional (2-D) models have shown that the rheology of the mantle wedge plays a critical role and establishes strong temperature gradients in the slab. The influence of threedimensional (3-D) subduction zone geometry on thermal structure is however not yet well characterized. A common assumption for 2-D models is that the cross-section is taken normal to the strike of the trench with a corresponding velocity reduction in the case of oblique subduction, rather than taken parallel to velocity. A comparison between a full 3-D Cartesian model with oblique subduction and selected 2-D cross-sections demonstrates that the trench-normal crosssection provides a better reproduction of the slab thermal structure than the velocity-parallel cross-section. An exception is found in the case of a strongly curved trench, such as in the Marianas, where strong 3-D flow in the mantle wedge is generated. In this case it is shown that the full 3-D model should be evaluated for an accurate prediction of the slab thermal structure. The models demonstrate that the use of a dynamic slab and wedge, separated by a kinematic boundary, yields good results for describing slab velocities in 3-D.

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Slab surface temperature in subduction zones: Influence of the interplate decoupling depth and upper plate thinning processes

Cited by 73 publications

References 67 publications

Dynamics of interplate domain in subduction zones: influence of rheological parameters and subducting plate age

Dynamics of interplate domain in subduction zones: influence of rheological parameters and subducting plate age

Rheologic controls on slab dynamics

Three-dimensional thermal structure of subduction zones: effects of obliquity and curvature

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