Extreme Compression of Calcium Silicate Perovskite: Clues to Earth's Deepest Mantle

The physical properties of complex silicate perovskites under extreme pressure and temperature conditions are critical for understanding the behavior and evolution of planetary interiors. We investigated the elasticity of multicomponent calcium silicate perovskite (davemaoite)—a phase expected to occur in recycled oceanic crust within Earth's lower mantle—using CO₂ laser-heated diamond anvil cell combined with Brillouin scattering and synchrotron X-ray diffraction up to 113 GPa and 2294 K. The material exhibits shear-wave velocities (Vs) 10–20% slower than those of endmember CaSiO₃ perovskite, indicating pronounced elastic softening induced by Fe, Al, Mg, and Ti substitution. Among the major lower-mantle minerals, this compositionally complex davemaoite is exceptionally weak elastically. Its enrichment readily account for the large low-shear-velocity provinces and ultra-low-velocity zones observed seismically at the base of the mantle, and can play a key role in triggering mantle plume formation near the core–mantle boundary. These findings highlight the vital role of high-pressure materials physics in linking atomic-scale structural properties to large-scale geophysical processes and planetary evolution.