The effect of bulk composition and temperature on mantle seismic structure

Xu, Weibin; Lithgow‐Bertelloni, Carolina; Stixrude, Lars; Ritsema, Jeroen

doi:10.1016/j.epsl.2008.08.012

Cited by 359 publications

(480 citation statements)

References 53 publications

(48 reference statements)

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“…Although the most common assumption is that the whole mantle has a pyro lite-like composition (e.g., McDonough and Sun, 1995;Lyubetskaya and Korenaga, 2007)-with some amount of heterogeneity from recycled subducted slabs (Xu et al, 2008)-some studies have questioned this assumption. Discrepancies between the velocity and density jumps in spherical seismic models and estimates from experiments on phase transitions in olivine or pyro lite, as well as Earth evolution and geochemical and cosmochemical arguments have been used to advocate that there is an intrinsic chemical difference between upper and lower mantle (e.g., Stixrude et al, 1992;Khan et al, 2008;Javoy et al, 2010).…”

Section: Density Jumpmentioning

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: Density Jumpmentioning

confidence: 99%

“…The depth range of the garnet transition and its Clapeyron slope are uncertain (Hirose, 2002;Xu et al, 2008;Stixrude and Lithgow-Bertelloni, 2011;Holland et al, 2013). In any case, the transition of the garnet components is rather diffuse and may spread over a depth interval as large as 100-250 km.…”

Section: Endothermic Phase Transitionmentioning

confidence: 99%

Subduction-transition zone interaction: A review

et al. 2017

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“…However, other formalisms/ databases [e.g., Xu et al, 2008] can be easily implemented by slightly modifying the relevant subroutine of the forward module. All necessary files containing thermodynamic information can be generated either with the freely available software Perple_X (http://www.perplex.ethz.ch) [Connolly, 2005] or by using a simple interface provided with LitMod3D.…”

Section: Thermodynamic Modeling and Bulk Propertiesmentioning

confidence: 99%

LitMod3D: An interactive 3‐D software to model the thermal, compositional, density, seismological, and rheological structure of the lithosphere and sublithospheric upper mantle

Fullea¹,

Afonso

Connolly

et al. 2009

Geochem Geophys Geosyst

123

166

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[1] We present an interactive 3-D computer program (LitMod3D) developed to perform combined geophysical-petrological modeling of the lithosphere and sublithospheric upper mantle. In contrast to other available modeling software, LitMod3D is built within an internally consistent thermodynamicgeophysical framework, where all relevant properties are functions of temperature, pressure, and composition. By simultaneously solving the heat transfer, thermodynamic, rheological, geopotential, and isostasy (local and flexural) equations, the program outputs temperature, pressure, surface heat flow, density (bulk and single phase), seismic wave velocities, geoid and gravity anomalies, elevation, and lithospheric strength for any given model. These outputs can be used to obtain thermal and compositional models of the lithosphere and sublithospheric upper mantle that simultaneously fit all available geophysical and petrological observables. We illustrate some of the advantages and limitations of LitMod3D using synthetic models and comparing our predictions with those from other modeling methods. In particular, we show that (1) temperature at midlithosphere depths may be overestimated by as much as 200 K when compositional heterogeneities in the mantle and T-P effects are not considered in lithospheric models and (2) the neglect of mantle phase transformations on gravity-based models in thin-crust settings can result in a significant overestimation and underestimation of the derived crustal thickness and its internal density distribution, respectively.

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“…A second synthetic (Fig. 9A) includes the effects of eclogite on seismic velocities [according to Xu et al (2008), cf. Table S1].…”

Section: Comparison With Seismic Modelsmentioning

confidence: 99%