On the deep carbon cycle in numerical modelling of mantle convection: Implications for the long-term climate evolution

Abstract

A model of deep-water and carbon cycles was developed to elucidate the mechanisms governing the carbon cycle in Earth's deep interior. This model integrates the solubility limit of carbon in mantle rocks into numerical simulations of mantle convection. To account for the total carbon released from the deep interior, I considered both the carbon release flux through metamorphic decarbonization during subduction and the outgassing fluxes at mid-ocean ridges and hotspots. Additionally, the model assumes a carbon solubility of 1.0 wt% at the top of the mantle transition zone. The carbon budget within Earth's deep interior appears nearly balanced by the carbon uptake during subduction and the decarbonization of the subducting slab through metamorphic reactions. This study also suggests that a warmer climate is likely if the carbon release flux from the deep interior comprises both decarbonization and volcanic outgassing. Therefore, an Earth-like climate may be sustained by the carbon release associated with plate subductions. It is acknowledged that this study presents a case study of carbon cycle modelling in mantle convection simulations, with a specific emphasis on the integration of carbon solubility limits in mantle rocks based on the carbon solubility model in mantle minerals.