Can Hadean thermochemical plumes erupt? Insights from a high-Rayleigh number thermal lattice-Boltzmann mantle convection model

The existence and eruptibility of mantle plumes in the Hadean-early Archean mantle are fundamental to interpreting the scarcity and timing of komatiites and other ultramafic magmas. Existing approaches often rely on parameterized thermal evolution or idealized forced-plume setups, so they rarely test plume eruptibility in fully convecting, high-Rayleigh whole-mantle dynamics. We use a thermal lattice-Boltzmann mantle convection approach with a multiphase formulation to test whether thermochemical plumes in a hot, vigorous, post-magma-ocean mantle can dynamically reach the surface, and under which conditions they are expected to erupt rather than stall and pond.

We simulate whole-mantle convection in annular geometry, solving Boussinesq Stokes flow coupled to heat advection-diffusion, and explore Hadean-like thermal structures at high Rayleigh numbers. Deformation is governed by nonlinear, visco-plastic rheology with Reynolds temperature-dependent viscosity, allowing transitions between weak- and strong-lid regimes via depth-dependent yield stress. Thermochemical plumes are represented by introducing a dense (e.g., eclogite-rich) component in the deep mantle that can be entrained into rising hot material, enabling us to quantify how compositional loading modifies plume ascent, head-tail structure, and interaction with the lithosphere. Melting is implemented within the simulations: melt generation, extraction, and retention are explicitly coupled so that density and viscosity evolve continuously as function of temperature, melt fraction, and composition.

Across the parameter suite, we track plume head trajectories, maximum ascent depth, and the spatiotemporal distribution of melt production/extraction to map an “eruption window” in Rayleigh-rheology-composition space. We compare this dynamical window with the observed timing and abundance of komatiites, and infer how thermochemical structure near the core-mantle boundary may have regulated the longevity and eruptibility of early Earth plumes.