Iron Partitioning and Density Changes of Pyrolite in Earth’s Lower Mantle

Abstract

Spin Transitions and Mantle Phases The extreme temperatures and pressures at depth can cause mantle minerals to undergo phase transformations. For example, it is thought that an electronic spin transition that occurs at high pressures in the lower mantle leads to the partitioning of various iron mineral phases. Using a multianvil apparatus to study a synthetic material similar in composition to the lower mantle, Irifune et al. (p. 193 , see the Perspective by Hirose ; published online 3 December) demonstrate that the spin transition occurs at lower pressures, and thus shallower depth, than suggested by earlier studies based on simpler compositions. As verification of the material's applicability in lower mantle studies, its density profile with pressure overlaps very well with those predicted by seismological models.