Structure and Dynamics of Earth's Lower Mantle
Edward J. Garnero* and
Allen K. McNamara
Processes within the lowest several hundred kilometers of Earth's rocky mantle play a critical role in the evolution of the planet. Understanding Earth's lower mantle requires putting recent seismic and mineral physics discoveries into a self-consistent, geodynamically feasible context. Two nearly antipodal large low-shear-velocity provinces in the deep mantle likely represent chemically distinct and denser material. High-resolution seismological studies have revealed laterally varying seismic velocity discontinuities in the deepest few hundred kilometers, consistent with a phase transition from perovskite to post-perovskite. In the deepest tens of kilometers of the mantle, isolated pockets of ultralow seismic velocities may denote Earth's deepest magma chamber.
School of Earth and Space Exploration, Arizona State University, Box 871404, Tempe, AZ 85287, USA.
* To whom correspondence should be addressed. E-mail: garnero{at}asu.edu
