A schematic summary. Time evolves in a clockwise direction. The dashed line marks a depth of 500 km, and the dotted shading indicates the pressure–temperature range where the wadsleyite ⇔ garnet (majorite) + ferropericlase phase transformation occurs. Purple shading marks areas of partial melting. The timeline calculation assumes a mantle potential temperature of 1900 K at ~3 Ga, cooling by about 100 K per Gyr.
Phase Transitions Control Plume Layering During Earth’s Secular Cooling
Earth’s mantle convects, cooling the planet and shaping both its internal structure and surface tectonic regimes. While models and observations provide reasonable constraints on present-day mantle flow, it remains an open question how patterns of mantle convection have evolved throughout Earth’s history. A key factor is temperature. In their recent study, Li et al. (2025) investigated how varying phase transitions affect convection styles using numerical models. The figure above summarizes their findings, showing that phase transitions can lead to the formation of layered plumes in hotter mantles.
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Contributed by: Ranpeng Li, Juliane Dannberg, Rene Gassmöller - GEOMAR Helmholtz Centre for Ocean Research Kiel; Carolina Lithgow-Bertelloni, Lars Stixrude - Earth, Planetary, and Space Sciences, University of California, Los Angeles
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