The effect of rheological parameters on plate behaviour in a self-consistent model of mantle convection

Stein, Claudia; Schmalzl, J.; Hansen, Ulrich

doi:10.1016/j.pepi.2004.01.006

Cited by 155 publications

(164 citation statements)

References 111 publications

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“…However, existing computations can provide clues on the Earth's behavior. Variations in heat flow with d ϳ 0.1% every Myr are typical of mobile lid convection (42), and dramatic plate reorganizations may lead to values that exceed 0.1% every Myr (43,44). Our results are therefore consistent with theoretical expectations of convective fluctuations in heat flow.…”

Section: Discussionmentioning

confidence: 99%

Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

Loyd

Becker²,

Conrad³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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The thermal evolution of Earth is governed by the rate of secular cooling and the amount of radiogenic heating. If mantle heat sources are known, surface heat flow at different times may be used to deduce the efficiency of convective cooling and ultimately the temporal character of plate tectonics. We estimate global heat flow from 65 Ma to the present using seafloor age reconstructions and a modified half-space cooling model, and we find that heat flow has decreased by ϳ0.15% every million years during the Cenozoic. By examining geometric trends in plate reconstructions since 120 Ma, we show that the reduction in heat flow is due to a decrease in the area of ridge-proximal oceanic crust. Even accounting for uncertainties in plate reconstructions, the rate of heat flow decrease is an order of magnitude faster than estimates based on smooth, parameterized cooling models. This implies that heat flow experiences short-term fluctuations associated with plate tectonic cyclicity. Continental separation does not appear to directly control convective wavelengths, but rather indirectly affects how oceanic plate systems adjust to accommodate global heat transport. Given that today's heat flow may be unusually low, secular cooling rates estimated from present-day values will tend to underestimate the average cooling rate. Thus, a mechanism that causes less efficient tectonic heat transport at higher temperatures may be required to prevent an unreasonably hot mantle in the recent past.global heat flow ͉ mantle convection ͉ plate reconstructions ͉ seafloor spreading E arth's heat loss is fueled by two dominant sources: (i) decay of radioactive elements within the planet's interior and (ii) secular cooling of the mantle (see reviews in refs. 1 and 2). Approximately 70% of Earth's total heat loss of ϳ46 TW occurs through oceanic lithosphere (ref. 2, referred to hereafter as J07) because it is the only part of the surface that actively participates in mantle convection. This component is also subject to the tectonic evolution of the ocean basins: the geometry of these basins and the organization of the plates within them change over the course of the Wilson cycle (e.g., refs. 3 and 4). If oceanic heat flow is sensitive to these changes, then global heat flow might have been different in the recent past. Temporal variations in Earth's heat flow have important implications for mantle dynamics and can influence parameterized models of Earth's thermal evolution (e.g., ref. 5, referred to hereafter as G05). New tectonic reconstructions of seafloor age (e.g., ref. 6, referred to hereafter as X06; see also refs. 7 and 8) present an opportunity to constrain the time variability of mantle heat flow directly and so provide new insights into the relationship between plate tectonics and Earth's thermal evolution.Global heat flow is dominated by young oceanic crust, with minor contributions from older oceanic crust, plume activity, and continental radiation (see, e.g., discussion in J07). Recently erupted mid-ocean ridge basalt conducts hea...

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Section: Discussionmentioning

confidence: 99%

Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

Loyd

Becker²,

Conrad³

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…Trompert and Hansen [1998] found episodic self-consistent plate-like behavior in a three-dimensional box model, interrupted by periods with a stagnant lid. Stein et al [2004] added the pressure dependence of viscosity and of thermal expansivity to such a model and found continuous plate motion and the appearance of an asthenosphere. Tackley [2000b] has also investigated the influence of pressure dependence of viscosity on plate motion.…”

Section: Plate-like Motions Of the Lithospherementioning

confidence: 99%

Mantle convection and evolution with growing continents

Walzer

Hendel

2008

J. Geophys. Res.

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[1] We present a three-dimensional spherical shell numerical model for chemical differentiation and redistribution of incompatible elements in a convective Earth's mantle heated mostly from within by U, Th, and K and slightly from below. The evolution-model equations guarantee conservation of mass, momentum, energy, angular momentum, and four sums of the number of atoms of the pairs 238 U-206 Pb, 235 U-207 Pb, 232 Th-208 Pb, and 40 K-40 Ar. The pressure-and temperature-dependent viscosity is supplemented by a viscoplastic yield stress, s y . The lithospheric viscosity is partly imposed to mimic its increase by dehydration of oceanic lithosphere and other effects. Also, the asthenosphere is generated not only by the distribution of temperature and melting temperature, but essentially by the profiles of water solubility and water abundance. Therefore we introduced a radial viscosity profile factor describing that behavior. However, the focus of this paper is the episodic growth of continents and oceanic plateaus. As a complement, the differentiation generates the depleted MORB mantle (DMM) which predominates immediately beneath the lithosphere. Our continents are not artificially imposed on the surface of the spherical shell, but instead they evolve by the interplay between chemical differentiation and convection/mixing. No restrictions are imposed regarding number, size, form, and distribution of continents. However, oceanic plateaus that impinge upon a continent have to be united with it. This mimics the accretion of terranes. The numerical results show an episodic growth of the total mass of the continents and display a plausible time history for the laterally averaged surface heat flow, qob, and the Rayleigh number, Ra. We use our model to explore a moderate region of Ra-s y parameter space. We find Earth-like continent distributions in a central part of the Ra-s y space we explored. We identified a Ra-s y region where the calculated total continental volume is very close to the observed value; another Ra-s y region where the Urey number, Ur, is close to the accepted value; a third Ra-s y area where surface heat flow is very close to the present-day observed mean global heat flow using typical abundances of the heat-producing elements. It is remarkable that these different acceptable Ra-s y regions share a common overlap area, where Earth-like behavior is simultaneously fulfilled.Although the convective flow patterns and the chemical differentiation of oceanic plateaus are coupled, the evolution of time-dependent Rayleigh number, Ra t , is relatively well predictable and the stochastic parts of the Ra t (t) curves are small. Regarding the time distribution of juvenile growth rates of the total mass of the continents, predictions are possible only in the first epoch of the evolution, presumed that the initial conditions are given. Later on, the distribution of the continental growth episodes is increasingly stochastic. Independent of the varying individual runs, our model shows that the total mass of the presen...

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“…Plate tectonics involves more than the formation of weak plate margins. However, a focus on plate deformation and localized failure allows for conservative mapping of the conditions under which plate tectonics is more or less likely to occur [e.g., Moresi and Solomatov, 1998;Stein et al, 2004;Tackley, 2000;Trompert and Hansen, 1998]. …”

Section: Introductionmentioning

confidence: 99%

The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

2016

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We use 1‐D thermal history models and 3‐D numerical experiments to study the impact of dynamic thermal disequilibrium and large temporal variations of normal and shear stresses on the initiation of plate tectonics. Previous models that explored plate tectonics initiation from a steady state, single plate mode of convection concluded that normal stresses govern the initiation of plate tectonics, which based on our 1‐D model leads to plate yielding being more likely with increasing interior heat and planet mass for a depth‐dependent Byerlee yield stress. Using 3‐D spherical shell mantle convection models in an episodic regime allows us to explore larger temporal stress variations than can be addressed by considering plate failure from a steady state stagnant lid configuration. The episodic models show that an increase in convective mantle shear stress at the lithospheric base initiates plate failure, which leads with our 1‐D model to plate yielding being less likely with increasing interior heat and planet mass. In this out‐of‐equilibrium and strongly time‐dependent stress scenario, the onset of lithospheric overturn events cannot be explained by boundary layer thickening and normal stresses alone. Our results indicate that in order to understand the initiation of plate tectonics, one should consider the temporal variation of stresses and dynamic disequilibrium.

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The effect of rheological parameters on plate behaviour in a self-consistent model of mantle convection

Cited by 155 publications

References 111 publications

Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

Time variability in Cenozoic reconstructions of mantle heat flow: Plate tectonic cycles and implications for Earth's thermal evolution

Mantle convection and evolution with growing continents

The importance of temporal stress variation and dynamic disequilibrium for the initiation of plate tectonics

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