1993/05/07 by Shun‐ichiro Karato, Patrick Wu · 11 citations
Earth and Planetary Sciences · #High-pressure geophysics and materials #Geological and Geochemical Analysis #earthquake and tectonic studies
paper · doi:10.1126/science.260.5109.771
openalex publication_date 1993/05/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
Rheological properties of the upper mantle of the Earth play an important role in the dynamics of the lithosphere and asthenosphere. However, such fundamental issues as the dominant mechanisms of flow have not been well resolved. A synthesis of laboratory studies and geophysical and geological observations shows that transitions between diffusion and dislocation creep likely occur in the Earth's upper mantle. The hot and shallow upper mantle flows by dislocation creep, whereas cold and shallow or deep upper mantle may flow by diffusion creep. When the stress increases, grain size is reduced and the upper mantle near the transition between these two regimes is weakened. Consequently, deformation is localized and the upper mantle is decoupled mechanically near these depths.