Assessing the role of thermal disequilibrium in the evolution of the lithosphere–asthenosphere boundary: an idealized model of heat exchange during channelized melt transport

Abstract. This study explores how the continental lithospheric mantle (CLM) may be heated during channelized melt transport when there is thermal disequilibrium between (melt-rich) channels and surrounding (melt-poor) regions. Specifically, I explore role of heat exchange in weakening destabilizing lithosphere from beneath as melts infiltrate into lithosphere–asthenosphere boundary (LAB) intraplate settings. During equilibration, hotter-than-ambient would expected to CLM, but we lack an understanding spatiotemporal scales these depend on channel geometries, infiltration duration, rates. assesses migrating material melt-rich their surroundings limit where advective effects are larger than diffusive transfer (Péclet numbers > 10). utilize a 1D advection–diffusion model that includes melt-poor region, parameterized by volume fraction (ϕ), average relative velocity (vchannel) inside outside channels, spacing (d), timescale episodic or repeated (τ). The results suggest following: (1) melt, steady-state reworking zone (TRZ) associated with spatiotemporally varying forms at LAB. (2) TRZ grows transient migration disequilibrium-heating front material-dependent velocity, reaching maximum width δ proportional ϕvchannel(τ/d)n, n≈2 for periodic perturbations n≈1 single finite-duration pulse. For geologically reasonable parameters, establishment comparable those inferred LAB based geologic observations within intra-plate settings, such western US. this that, speeds vchannel=1 m yr−1, spacings d≈102 m, timescales τ≈101 kyr, lowermost CLM ≈10 km. (3) Within TRZ, contribute ≈10-5 W m−3 budget.