Geodynamic Controls on Mantle Differentiation and Preservation of Long‐Term Geochemical Heterogeneity: Focus on the Primitive Undegassed Mantle

Journal article

Plain Language Summary: Partial melting of mantle materials allows for degassing and creates compositional heterogeneities that can be preserved for several billion years as suggested by geochemical observations. Helium and argon data suggest that heterogeneities, potentially nearly as old as the age of the Earth, undegassed, are preserved within the planet's interior. Previous works have shown that increasing the viscosity or density of mantle materials can help maintaining them from melting and degassing. However, the role of mantle convection in controlling the amount of material processed in melting zones through time (i.e., the processing history) is unclear. Therefore, the influence of fundamental convection parameters (e.g., viscosity, radiogenic heat input) on the processing history are investigated using 3D spherical simulations. The resulting preservation of primitive undegassed material is systematically analyzed. Results show that the processing history relates to the thermal evolution of the mantle and that different types of material are processed depending on surface velocities and shallow temperatures. A preservation mechanism is the dispersal of primitive material by convection, allowing the material's temperature to converge to that of the average mantle. Results show that some geodynamical contexts and processing histories are more favorable to the preservation of material than others.

Authors: Récalde, N; Davies, JH; Panton, J; Porcelli, D; Andersen, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Geochemistry, Geophysics, Geosystems
• Volume: 27
• Issue: 3
• Article number: e2025GC012516
• Publication date: 2026-03-12
• Acceptance date: 2026-03-02
• DOI: 10.1029/2025gc012516
• EISSN: 1525-2027
• ISSN: 1525-2027
• Language: English
• Keywords: mantle dynamics; mantle differentiation; numerical modeling; thermal evolution; primitive mantle