title: Structure and dynamics of Earth's lower mantle.
abstract: 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.
authors.affiliation: School of Earth and Space Exploration, Arizona State University, Box 871404, Tempe, AZ 85287, USA. garnero@asu.edu
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Garnero
authors.forename: Allen K
authors.initials: AK
authors.lastname: McNamara