The viscosity of Earth’s lower mantle inferred from sinking speed of subducted lithosphere

Čı́žková, Hana; Berg, A. P. van den; Spakman, Wim; Matyska, Ctirad

doi:10.1016/j.pepi.2012.02.010

Cited by 112 publications

(47 citation statements)

References 41 publications

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“…In contrast, the other viscosity models for which results are displayed here and in supporting information Figure S2 yield generally reasonable tilts for mantle plumes globally (e.g., Torsvik et al, ). Similar results were also found for the A‐family viscosity model from Čížková et al (), which has similar magnitude and shape as the model in Figure , left. Their B‐family model yields smaller tilts, because of a higher‐viscosity maximum in the lower mantle (note that in their Figure 1 the Steinberger and Calderwood () viscosity model is wrongly scaled; the maximum of the blue line in their Figure 1b is actually substantially higher than for the S&C, 2006 model).…”

Section: Results: Plume Conduit Rising From South‐southwest and Hot Ssupporting

confidence: 86%

Yellowstone Plume Conduit Tilt Caused by Large‐Scale Mantle Flow

Steinberger

Nelson

Grand

et al. 2019

Geochem Geophys Geosyst

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Mantle plumes are hot upwellings of rock thought to originate at the core-mantle boundary.As they rise through the mantle, their conduits may become tilted due to lateral large-scale mantle flow. Recent tomographic images have revealed a strongly tilted plume conduit starting at the core-mantle boundary beneath northern Baja California rising toward the Yellowstone hot spot from the southwest. Here we perform numerical computations of plumes deflected in large-scale mantle flow with the aim of finding if realistic model parameter ranges exist that yield a good fit with the tomographically observed conduit. We restrict ourselves to models that yield reasonable results for plume conduit tilt and hot spot motion globally. These models require high viscosity ≈10 23 Pa s at some lower mantle depths. For a plume head reaching the surface 17 Ma, corresponding to the start of the Columbia River Basalts, our models require rise times ≈80 Myr or longer to match the tilt of the conduit observed by tomography. We used several tomography models to determine mantle density with almost all models predicting southwestward flow in the lowermost mantle beneath the western United States. Exact details of the shape of the predicted conduit's southwesterly tilt vary, depending on the density and viscosity structures we used. In many cases we find comparatively strong tilts in two depth ranges, in the upper and lower portions of the mantle, which is also a characteristic of the tomographically observed conduit. We expect that future models may help to constrain large-scale flow by matching these corresponding depth ranges.

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Section: Results: Plume Conduit Rising From South‐southwest and Hot Ssupporting

confidence: 86%

Yellowstone Plume Conduit Tilt Caused by Large‐Scale Mantle Flow

Steinberger

Nelson

Grand

et al. 2019

Geochem Geophys Geosyst

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“…To compute the viscoelastic response, we assume constant viscosity values in the upper and lower mantles, ranging between 10 20 –10 21 Pa s and 10 22 –10 23 Pa s, respectively, consistent with the typical viscosity values derived from geophysical constraints [see Čížková et al , , and references therein]. For this range of viscosity and a parameter α between 0.2 and 0.3, we obtain a potential Love number for a semidiurnal tidal period between 0.303 and 0.304, which is consistent with the observed value estimated between 0.304 and 0.312 [ Ray et al , ].…”

Section: Computation Of Tidal Deformationsupporting

confidence: 81%

Tidal constraints on the interior of Venus

et al. 2017

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As a prospective study for a future exploration of Venus, we compute the tidal response of Venus' interior assuming various mantle compositions and temperature profiles representative of different scenarios of Venus' formation and evolution. The mantle density and seismic velocities are modeled from thermodynamical equilibria of mantle minerals and used to predict the moment of inertia, Love numbers, and tide‐induced phase lag characterizing the signature of the internal structure in the gravity field. The viscoelasticity of the mantle is parameterized using an Andrade rheology. From the models considered here, the moment of inertia lies in the range of 0.327 to 0.342, corresponding to a core radius of 2900 to 3450 km. Viscoelasticity of the mantle strongly increases the potential Love number relative to previously published elastic models. Due to the anelasticity effects, we show that the possibility of a completely solid metal core inside Venus cannot be ruled out based on the available estimate of k2 from the Magellan mission (Konopliv and Yoder, 1996). A Love number k2 lower than 0.27 would indicate the presence of a fully solid iron core, while for larger values, solutions with an entirely or partially liquid core are possible. Precise determination of the Love numbers, k2 and h2, together with an estimate of the tidal phase lag, are required to determine the state and size of the core, as well as the composition and viscosity of the mantle.

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“…Our modeled sinking speeds are higher than found by Cížková et al (2012) for the case where they use a similar viscosity structure. We think that this difference occurs mainly becauseČížková et al (2012) model relatively short episodes of subduction, whereas our model typically has subduction in the same region for a long time, leading to larger amounts of subducted slabs, and hence faster sinking.…”

Section: B Steinberger Et Al: Subduction To the Lower Mantle -Compacontrasting

confidence: 64%

Subduction to the lower mantle – a comparison between geodynamic and tomographic models

2012

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Abstract. It is generally believed that subduction of lithospheric slabs is a major contribution to thermal heterogeneity in Earth's entire mantle and provides a main driving force for mantle flow. Mantle structure can, on the one hand, be inferred from plate tectonic models of subduction history and geodynamic models of mantle flow. On the other hand, seismic tomography models provide important information on mantle heterogeneity. Yet, the two kinds of models are only similar on the largest (1000 s of km) scales and are quite different in their detailed structure. Here, we provide a quantitative assessment how good a fit can be currently achieved with a simple viscous flow geodynamic model. The discrepancy between geodynamic and tomography models can indicate where further model refinement could possibly yield an improved fit. Our geodynamical model is based on 300 Myr of subduction history inferred from a global plate reconstruction. Density anomalies are inserted into the upper mantle beneath subduction zones, and flow and advection of these anomalies is calculated with a spherical harmonic code for a radial viscosity structure constrained by mineral physics and surface observations. Model viscosities in the upper mantle beneath the lithosphere are ∼10 20 Pas, and viscosity increases to ∼10 23 Pas in the lower mantle above D " . Comparison with tomography models is assessed in terms of correlation, both overall and as a function of depth and spherical harmonic degree. We find that, compared to previous geodynamic and tomography models, correlation is improved, presumably because of advances in both plate reconstructions and mantle flow computations. However, high correlation is still limited to lowest spherical harmonic degrees. An important ingredient to achieve high correlation -in particular at spherical harmonic degree two -is a basal chemical layer. Subduction shapes this layer into two rather stable hot but chemically dense "piles", corresponding to the Pacific and African Large Low Shear Velocity Provinces. Visual comparison along cross sections indicates that sinking speeds in the geodynamic model are somewhat too fast, and should be 2 ± 0.8 cm yr −1 to achieve a better fit.

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The viscosity of Earth’s lower mantle inferred from sinking speed of subducted lithosphere

Cited by 112 publications

References 41 publications

Yellowstone Plume Conduit Tilt Caused by Large‐Scale Mantle Flow

Yellowstone Plume Conduit Tilt Caused by Large‐Scale Mantle Flow

Tidal constraints on the interior of Venus

Subduction to the lower mantle – a comparison between geodynamic and tomographic models

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