Key Points: <ul> <li><strong>Layering in Planetary Mantles</strong>: Degree of layering during planetary mantle evolution is a key issue, especially since seismic discontinuities were observed in Earth's mantle.</li> <li><strong>Seismic Discontinuities and Phase Transitions</strong>: Observations correlate mantle seismic discontinuities with phase transitions in mantle minerals, affecting geochemical profiles in mantle-derived basalts (MORBs and OIBs).</li> <li><strong>Double-Diffusive Layering</strong>: The study investigates double-diffusive layering in fluids with temperature-dependent viscosity, relevant to mantle material.</li> <li><strong>Influence of Initial Composition Gradients</strong>: Examines how initial compositional gradients impact thermal and chemical evolution in planetary mantles.</li> <li><strong>Numerical Experiments and Layer Formation</strong>: Experiments show that self-organized layers form through dynamic fractionation across a range of conditions, suggesting this as a generic mantle process.</li> <li><strong>Implications for Chemical Reservoirs</strong>: This model offers a dynamic explanation for the formation of distinct chemical reservoirs throughout planetary mantle history.</li> </ul>