Constraints on thermochemical convection of the mantle from plume heat flux, plume excess temperature, and upper mantle temperature

Zhong, Shijie

doi:10.1029/2005jb003972

Cited by 199 publications

(179 citation statements)

References 60 publications

Supporting

Mentioning

164

Contrasting

Unclassified

Order By: Relevance

“…Because of the complexity in the Alaska subduction-transform boundary, SlabGenerator was written to take in generic shapes and therefore is easily portable to make input for other subduction zones. The initial 3D plate boundary configuration and thermal structure are then used as input to CitcomCU, a community mantle convection code developed by [25,23,32]. CitcomCU simulates viscous flow in the mantle given the driving forces imposed, in this case, by the thermal structure generated from SlabGenerator.…”

Section: Methodsmentioning

confidence: 99%

“…where u, σ, ρo, α, T, To, g, δ, κ are the flow velocity, stress tensor, density, coefficient of thermal expansion, temperature, reference temperature, acceleration due to gravity, Kronecker delta, and thermal diffusivity, respectively [32]. The constitutive relation is defined by…”

Section: Community Mantle Convection Codementioning

confidence: 99%

“…The discretized conservation of mass equation is used as a penalty constraint on the pressure. CitcomCU implements the full multigrid method (FMG) to reduce the velocity residual and accelerate convergence [32].…”

Section: Community Mantle Convection Codementioning

confidence: 99%

See 2 more Smart Citations

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

Jadamec

Billen

Kreylos

2012

Proceedings of the 1st Conference of the Extreme Science and Engineering Discovery Environment: Bridging From the eXtreme to Th

View full text Add to dashboard Cite

The incorporation of geologic realism into numerical models of subduction is becoming increasingly necessary as observational and experimental constraints indicate plate boundaries are inherently three-dimensional (3D) in nature and contain large viscosity variations. However, large viscosity variations occurring over short distances pose a challenge for computational codes, and models with complex 3D geometries require substantially greater numbers of elements, increasing the computational demands. We modified a community mantle convection code, CitcomCU, to model realistic subduction zones that use an arbitrarily shaped 3D plate boundary interface and incorporate the effects of a strainrate dependent viscosity based on an experimentally derived flow law for olivine aggregates. Tests of this implementation on 3D models with a simple subduction zone geometry indicate that limiting the overall viscosity range in the model, as well as limiting the viscosity jump across an element, improves model runtime and convergence behavior, consistent with what has been shown previously. In addition, the choice of method and averaging scheme used to transfer the viscosity structure to the different levels in the multigrid solver can significantly improve model performance. These optimizations can improve model runtime by over 20%. 3D models of a subduction zone with a complex plate boundary geometry were then constructed, containing over 100 million finite element nodes with a local resolution of up to 2.35 km, and run on XSEDE. These complex 3D models, representative of the Alaska subduction zone-transform plate boundary, contain viscosity variations of up to seven orders of magnitude. The optimizations in solver parameters determined from the simple 3D models of subduction applied to the much larger and more complex models of an actual subduction zone im- * Corresponding author.Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. proved model convergence behavior and reduced runtimes by on the order of 25%. One scientific result from 3D models of Alaska is that a laterally variable mantle viscosity emerges in the mantle as a consequence of variations in the flow field, with localized velocities of greater than 80 cm/yr occurring close to the subduction zone where the negative buoyancy of the slab drives the flow. These results are a significant departure from the paradigm of two-dimensional (2D) models of subduction where the slab velocity is often fixed to surface plate motion. While the solver parameter optimization can improve model performance, the results also demonstrate the need for new solvers to keep pace with the demands for increasingly complex numerical...

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Community Mantle Convection Codementioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

Jadamec

Billen

Kreylos

2012

Proceedings of the 1st Conference of the Extreme Science and Engineering Discovery Environment: Bridging From the eXtreme to Th

View full text Add to dashboard Cite

show abstract

“…'Primary', deep hotspot plumes (Courtillot et al 2003) are thought to originate at the thermal boundary layer at the base of the lower mantle (e.g., Zhong 2006;Boschi et al, 2007). In some areas of the core-mantle boundary (CMB), anomalous seismic properties within thin zones (~ 10 km thick and 50-100 km wide) were identified as Ultra-Low Velocity Zones (ULVZ) due to their drop in seismic velocities greater than 10 % relative to the background mantle.…”

Section: Carbon Diamond and Hotspotsmentioning

confidence: 99%

A primary natrocarbonatitic association in the Deep Earth

2015

View full text Add to dashboard Cite

In addition to ultramafic and mafic associations, a primary natrocarbonatitic association occurs in the lower mantle. To date, it was identified as inclusions in diamonds from the Juina area, Mato Grosso State, Brazil. It comprises almost 50 mineral species: carbonates, halides, fluorides, phosphates, sulfates, oxides, silicates, sulfides and native elements. In addition, volatiles are present in this association. Among oxides, coexisting periclase and wüstite were identified, pointing to the formation of the natrocarbonatitic association at a depth greater than 2,000 km. Some ironrich (Mg,Fe)O inclusions in diamond are attributed to the lowermost mantle. The initial lower-mantle carbonatitic melt formed as a result of low-fraction partial melting of carbon-containing lower-mantle material, rich in P, F, Cl and other volatile elements, at the core-mantle boundary. During ascent to the surface, the initial carbonatitic melt dissociated into two immiscible parts, a carbonate-silicate and a chloride-carbonate melt. The latter melt is parental to the natrocarbonatitic lower-mantle association. Diamonds with carbonatitic inclusions were formed in carbonatitic melts or high-density fluids.

show abstract

“…Recent calculations that show that the lower mantle may be subadiabatic with a superadiabatic region above the core-mantle boundary (e.g., Bunge et al, 2001;Monnereau and Yuen, 2002;Zhong, 2006); this reduces the problem to some extent. This problem will be examined further in the discussion.…”

Section: Introductionmentioning

confidence: 99%

The structure of thermal plumes and geophysical observations

King¹,

Redmond²

2007

Special Paper 430: Plates, Plumes and Planetary Processes

View full text Add to dashboard Cite

We present a sequence of numerical experiments studying thermal plumes that arise from the basal thermal boundary layer in a spherical axisymmetric convecting fluid, reporting the geoid, topographic (swell), and heatflow anomalies. We consider the influence of spherical geometry, temperature-and pressure-dependence of rheology, internal heat generation, pressuredependent coefficient of thermal expansion, the Clapeyron slope of the endothermic phase transformation, and compositional layering at the base of the mantle on the structure and dynamics of thermal plumes and resulting geophysical anomalies. This fluid system simplifies a number of complexities within the Earth (e.g., it is not compressible, does not include plate motions, enforces axisymmetric symmetry, and has a simple equation of state); however, this system is computationally tractable and provides an opportunity to evaluate each effect in a systematic fashion. With the assumptions listed above we are formally unable to reproduce the observed hotspot swell, heatflow, and geoid anomalies from the resulting thermal plumes. The calculations that most closely approach the observed geoid, topographic and heatflow anomalies contain all the effects mentioned above. One particularly interesting aspect of these calculations is that when we include depth-dependent coefficient of thermal expansion the plume conduits in the lower 500 kilometers of the mantle are more than 200 km in diameter wider than with an otherwise identical, uniform coefficient of thermal expansion calculation. We speculate that the lack of mobile plates in our calculations, which would both advect upwelling material away from the plume conduit and change the global cooling mechanism, is a major shortcoming and that it may be possible to reconcile thermal plume calculations with the geoid, topography, and heatflow observations if we included mobile plates.3

show abstract

Constraints on thermochemical convection of the mantle from plume heat flux, plume excess temperature, and upper mantle temperature

Cited by 199 publications

References 60 publications

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

Three-dimensional simulations of geometrically complex subduction with large viscosity variations

A primary natrocarbonatitic association in the Deep Earth

The structure of thermal plumes and geophysical observations

Contact Info

Product

Resources

About