The Sensitivity of Core Heat Flux to the Modeling of Plate‐Like Surface Motion

Abstract

The generation of a magnetic field and the presence of tectonic plates are fundamental aspects of Earth's evolution. Viable dynamic models of terrestrial mantle convection therefore require the existence of heat transport from the core and a surface characterized by piecewise uniform surface velocity domains (i.e., plates). To test the compatibility of these two requirements, we varied energy input, rheology, and compositional heterogeneity in more than 70 mantle convection simulations. Calculations are performed in a spherical annulus geometry. By systematic investigation, we demonstrate that Earth‐like core heat flux can be obtained with self‐consistent model plates. We find that, given an initial condition where model parameters are chosen to ensure a mobile surface, the mobility is not strongly influenced when H is varied by up to a factor of three. Consequently, in spherical models with steady core temperatures and internal heating rates, the latter quantity can be used to regulate core heat flow to fit within the bounds inferred for terrestrial values. In contrast, core heat flow is strongly sensitive to model yield stress. We systematically vary thermal viscosity contrast, an intrinsic depth‐dependent viscosity and the depth‐dependence of a stress‐dependent rheology and analyze how each factor affects both surface velocities and core heat flux. Finally, we show that the addition of an intrinsically dense component comprising 5% or less of the mantle volume does not affect surface mobility or plateness, although it can have a profound impact on heat loss from the core.

Craton Formation in Early Earth Mantle Convection Regimes

“…For values in between, an episodic mode of convection emerges, where the stagnant lid is interrupted by short-lived events involving lithosphere mobility and recycling. Although the scaling of Earth-like stresses goes beyond the These results agree with what has been found in many different setups, from Cartesian to spherical, and from two-to three-dimensional (Crameri & Tackley, 2015;Langemeyer et al, 2018;Solomatov & Moresi, 2000;Stein & Hansen, 2008;Tackley, 1998Tackley, , 2000van Heck and Tackley, 2008).…”

“…On the other hand, mantle tractions decrease with increasing internal heat, making tectonics less viable (O'Neill et al., 2007). Additionally, model aspect ratios and dimensions affect the tractions (Guerrero et al., 2018; Lowman & Jarvis, 1996); however, these only shift the cohesion value at which the regime transitions (Langemeyer et al., 2018).…”

Effects of the Compositional Viscosity Ratio on the Long‐Term Evolution of Thermochemical Reservoirs in the Deep Mantle

“…In this case, and as expected by our scenario, increasing compositional viscosity ratio helps to stabilize the reservoirs of primordial material and to maintain large amount of this material at the bottom of mantle (Figure c), in agreement with the findings of Heyn et al (). We further note that this case is in very good agreement with similar calculations conducted by Langemeyer et al (). In this study, we implicitly assume that LLSVPs are made of primordial material segregated at the bottom of the mantle as a result of the crystallization of a basal magma ocean, a process that might be long lasting (Labrosse et al, ; Trønnes et al, ).…”

Where does subduction initiate and cease? A global scale perspective

“…The plate size hence number of subduction zones is strongly influenced by how di cult it is for the lithosphere to localize deformation, which is directly related to the value of 0 . Decreasing the surface yield stress results in weaker oceanic lithosphere and smaller plates [Moresi and Solomatov, 1998;Tackley, 2000b;Coltice et al, 2017;Langemeyer et al, 2018]. For low yield stress ( 0 = MPa), a large population of subduction zones exists at a given instant, fluctuating around 7 and 8 (cf.…”