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SelfConsistent Generation of Tectonic Plates in TimeDependent, ThreeDimensional Mantle Convection Simulations, Part 1: PseudoPlastic Yielding
, 1999
"... . Presented here are the fi g4 threedigH66869gi sieedigH6 of mantle convecti6] to dig8q88 selfconsi5969gigi69gi6) plate tectoni9)qgH6 behavii whivi ii contii9)q io space and ti g4 Plate behavi;6 arivi through a reasonable materiab describle g of sig4)W8] deformati68W wifo a si598W yi598 stress be ..."
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Cited by 69 (11 self)
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. Presented here are the fi g4 threedigH66869gi sieedigH6 of mantle convecti6] to dig8q88 selfconsi5969gigi69gi6) plate tectoni9)qgH6 behavii whivi ii contii9)q io space and ti g4 Plate behavi;6 arivi through a reasonable materiab describle g of sig4)W8] deformati68W wifo a si598W yi598 stress beiss suffi5W;65 to gig4 fi488W5gH69 plateliH6 behaviiH ToroiiH69)69gi ratii are wi g85 geologi9gH5q]69giiW li5q]69 The sensi958gH5 of the system to yig5 strength and the form of strength envelope iv systemati;qW)g istemati;qW Optiema plate character ih obtaicte it a narrow range of yig;W strength, below whiwg diwg5W boundari9gH and above epie g4q behaviq;; and eventually a riW;5 liW; are observed. Models wiel mobis lii develop very longwavelength horiwavele structure the longest wavelength possieng is the domai85 Twodig5W; ]]gH5 models diels g much greater titer g;;W;]gH5 than threedie g5W;]8gH5;969g INTRODUCTION Platetectoni)g wit attendant contintg8q driti i arguably the most istg...
The generation of plate tectonics from mantle convection, Earth Planet
 Sci. Lett
, 2003
"... In the last decade, significant progress has been made toward understanding how plate tectonics is generated from mantle dynamics. A primary goal of plategeneration studies has been the development of models that allow the top cold thermal boundary layer of mantle convection, i.e. the lithosphere, ..."
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Cited by 48 (7 self)
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In the last decade, significant progress has been made toward understanding how plate tectonics is generated from mantle dynamics. A primary goal of plategeneration studies has been the development of models that allow the top cold thermal boundary layer of mantle convection, i.e. the lithosphere, to develop broad and strong platelike segments separated by narrow, weak and rapidly deforming boundaries; ideally, such models also permit significant strikeslip (toroidal) motion, passive ridges (i.e. pulled rather than pried apart), and selfconsistent initiation of subduction. A major outcome of work so far is that nearly all aspects of plate generation require lithospheric rheologies and shearlocalizing feedback mechanisms that are considerably more exotic than rheologies typically used in simple fluiddynamical models of mantle flow. The search for plategenerating behavior has taken us through investigations of the effects of shear weakening (‘stickslip’) and viscoplastic rheologies, of melting at ridges and lowviscosity asthenospheres, and of grainsize dependent rheologies and damage mechanics. Many such mechanisms, either by themselves or in combination, have led to selfconsistent fluidmechanical models of mantle flow that are remarkably platelike, which is in itself a major accomplishment. However, many other important problems remain unsolved, such as subduction intiation and asymmetry, temporal evolution of plate geometry, rapid changes in plate motion, and the Archaean initiation of the platetectonic mode of convection. This paper presents a brief review of progress made in the plategeneration problem over the last decade, and discusses unresolved issues and future directions of research in this important area.
A Lagrangian integration point finite element method for large deformation modeling of viscoelastic geomaterials
 20, 2003. CO 602 DEN JCTPAH. ISSN 00219991 (print), 10902716 (electronic). URL http://www.sciencedirect.com/science/ article/pii/S0021999102000311
"... We review the methods available for largedeformation simulations of geomaterials before presenting a Lagrangian integration point finite element method designed specifically to tackle this problem. In our EL LIPSIS code, the problem domain is represented by an Eulerian mesh and an embedded set of La ..."
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Cited by 37 (8 self)
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We review the methods available for largedeformation simulations of geomaterials before presenting a Lagrangian integration point finite element method designed specifically to tackle this problem. In our EL LIPSIS code, the problem domain is represented by an Eulerian mesh and an embedded set of Lagrangian integration points or particles. Unknown variables are computed at the mesh nodes and the Lagrangian particles carry history variables during the deformation process. This method is ideally suited to model fluidlike behavior of continuum solids which are frequently encountered in geological contexts. We present benchmark examples taken from the geomechanics area.
The relation between mantle dynamics and plate tectonics: a primer, the history and dynamics of global plate motions
 AGU Geophysical Monograph
, 2000
"... Abstract. We present an overview of the relation between mantle dynamics and plate tectonics, adopting the perspective that the plates are the surface manifestation, i.e., the top thermal boundary layer, of mantle convection. We review how simple convection pertains to plate formation, regarding th ..."
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Abstract. We present an overview of the relation between mantle dynamics and plate tectonics, adopting the perspective that the plates are the surface manifestation, i.e., the top thermal boundary layer, of mantle convection. We review how simple convection pertains to plate formation, regarding the aspect ratio of convection cells; the forces that drive convection; and how internal heating and temperaturedependent viscosity affect convection. We examine how well basic convection explains plate tectonics, arguing that basic plate forces, slab pull and ridge push, are convective forces; that seafloor structure is characteristic of thermal boundary layers; that slablike downwellings are common in simple convective flow; and that slab and plume fluxes agree with models of internally heated convection. Temperaturedependent viscosity, or an internal resistive boundary (e.g., a viscosity jump and/or phase transition at 660km depth) can also lead to large, plate sized convection cells. Finally, we survey the aspects of plate tectonics that are poorly explained by simple convection theory, and the progress being made in accounting for them. We examine nonconvective plate forces; dynamic topography; the deviations of seafloor structure from that of a thermal boundary layer; and abrupt platemotion changes. Platelike strength distributions and plate boundary formation are addressed by considering complex lithospheric rheological mechanisms. We examine the formation of convergent, divergent and strikeslip margins, which are all uniquely enigmatic. Strikeslip shear, which is highly significant in plate motions but extremely weak or entirely absent in simple viscous convection, is given ample discussion. Many of the problems of plate boundary formation remain unanswered, and thus a great deal of work remains in understanding the relation between plate tectonics and mantle convection. 1.
Evolution of U–Pb and Sm–Nd systems in numerical models of mantle convection andplate tectonics. J.Geophys
, 2004
"... [1] The development of UThPb and SmNd isotopic signatures in a convecting mantle is studied using a numerical convection model with meltinginduced differentiation and tracking of major and trace elements. The models include secular cooling and the decay of heatproducing elements, a rudimentary ..."
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Cited by 13 (2 self)
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[1] The development of UThPb and SmNd isotopic signatures in a convecting mantle is studied using a numerical convection model with meltinginduced differentiation and tracking of major and trace elements. The models include secular cooling and the decay of heatproducing elements, a rudimentary ‘‘selfconsistent’ ’ treatment of plate tectonics, and both olivine system and garnetpyroxene system phase transitions. The system selfconsistently evolves regions with a high m(=U/Pb) (HIMU)like Pb signature and regions with low 143Nd/144Nd. However, the isotopic ‘‘age’ ’ determined from the slope in (207Pb/204Pb)–(206Pb/204Pb) space is much larger than observed. Several hypotheses are examined to explain this discrepancy. Sampling length scale has a minimal effect on age. The extent of crustal settling above the coremantle boundary makes some difference but not enough. More frequent remelting is a possible explanation but requires the rate of crustal production to have been much higher in the past. Not introducing HIMU into the mantle prior to 2.0–2.5 Gyr before present, because of a change in the surface oxidization environment or subduction zone processes, can account for the difference, but its effect on other isotope systems needs to be evaluated. Improved
Evolution of the mode of convection within terrestrial planets
, 2000
"... Abstract. Magma oceans, plate tectonics, and stagnantlid convection have transferred heat out of the terrestrial planets at various times in their histories. The implications of the existence of multiple branches are graphically illustrated by approximating the globally averaged mantle heat flow as ..."
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Abstract. Magma oceans, plate tectonics, and stagnantlid convection have transferred heat out of the terrestrial planets at various times in their histories. The implications of the existence of multiple branches are graphically illustrated by approximating the globally averaged mantle heat flow as a function of the interior potential temperature. For this assumption to be valid, the mantle heat flow needs to be able to change rapidly relative to the potential temperature, or, equivalently, lithosphere needs to be a small fraction of the mass planet. This criterion is satisfied by the Earth, Venus, and Mars, but not the Moon. At a given potential temperature the function may be multivalued with a separate branch representing each mode of convection. The heat flow evolves along a branch as the potential temperature changes depending on whether the heat flow is greater or less than the global radioactive heat generation. When the end of a branch is reached, the state of the system jumps to another branch, quickly changing the global heat flow. Examples include transitions from a magma ocean to plate tectonics, probably on the Earth and Mars, and conceivably Venus; and the transition from a stagnantlid planet to a magma ocean on Venus and the eventual return to a stagnantlid planet. 1.
The Quest for SelfConsistent Generation of Plate Tectonics in Mantle Convection Models
"... This paper explores the quest for ..."
Growth of the hemispheric dichotomy and the cessation of plate tectonics on Mars
 Journal of Geophysical Research
, 2004
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A benchmark study on mantle convection in a 3D spherical shell using CitcomS, Geochem. Geophys. Geosyst., 9, Q10017, doi:10010.11029/12008GC002048. SUPPORTING INFORMATION Additional Supporting Information may be found in the online version of this articl
, 2008
"... [1] As highperformance computing facilities and sophisticated modeling software become available, modeling mantle convection in a threedimensional (3D) spherical shell geometry with realistic physical parameters and processes becomes increasingly feasible. However, there is still a lack of compre ..."
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Cited by 10 (0 self)
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[1] As highperformance computing facilities and sophisticated modeling software become available, modeling mantle convection in a threedimensional (3D) spherical shell geometry with realistic physical parameters and processes becomes increasingly feasible. However, there is still a lack of comprehensive benchmark studies for 3D spherical mantle convection. Here we present benchmark and test calculations using a finite element code CitcomS for 3D spherical convection. Two classes of model calculations are presented: the Stokes ’ flow and thermal and thermochemical convection. For Stokes ’ flow, response functions of characteristic flow velocity, topography, and geoid at the surface and coremantle boundary (CMB) at different spherical harmonic degrees are computed using CitcomS and are compared with those from analytic solutions using a propagator matrix method. For thermal and thermochemical convection, 24 cases are computed with different model parameters including Rayleigh number (7 103 or 105) and viscosity contrast due to temperature dependence (1 to 107). For each case, timeaveraged quantities at the steady state are computed, including surface and CMB Nussult numbers, RMS velocity, averaged temperature, and maximum and minimum flow velocity, and temperature at the midmantle depth and their standard deviations. For thermochemical convection cases, in addition to outputs for thermal convection, we also quantified entrainment of an initially dense component of the convection and the relative errors in
Tectonic plate generation and twophase damage: Void growth versus grain size reduction
 Journal of Geophysical Research
"... Abstract. The twophase theory for compaction and damage employs a nonequilibrium relation between interfacial surface energy, pressure, and viscous deformation, thereby providing a model for damage (void generation and microcracking) and a continuum description of weakening, failure, and shear l ..."
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Cited by 10 (6 self)
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Abstract. The twophase theory for compaction and damage employs a nonequilibrium relation between interfacial surface energy, pressure, and viscous deformation, thereby providing a model for damage (void generation and microcracking) and a continuum description of weakening, failure, and shear localization. Here we examine the application of this theory to the problem of generating platelike behavior from convectivetype divergent (poloidal) motion through a sourcesink formulation. We extend the previous damage theory to consider two possible damage effects: (1) growth and nucleation of voids associated with dilation of the host matrix, and (2) increasing fineness (i.e., reducing coarseness) of the mixture by, for example, grainsize reduction. Voidgenerating damage is found to be poor at plate generation because of the predominance of dilational motion that is adverse to the development of platelike flow. Finenessgenerating damage is found to be very efficient at generating platelike behavior if we assume that the matrix viscosity is a simple function of grain/void size, as is typical for diffusion creep. The implied grainsize reduction mechanism is different than that of dynamic recrystallization, and appears more capable of generating the requisite shearlocalization for forming tectonic plates from mantle flow.