These structures are the location of the dynamo that supports a planet's magnetic field.
The Bullen parameter quantifies the deviation of the density distribution of these structures from the AdamsWilliamson equation. Song and Richards first showed evidence of anisotropy in a part of this structure, which is partially a result of differential rotation. A restriction on the age of formation of these structures can be determined by hafnium/tungsten dating because hafnium is a lithophile and tungsten is a siderophile. Seismic waves traversing this (*) entire structure are denoted with both a capital K and I. Above the upper boundary of this structure lies post-perovskite in the D-double prime layer. These structures are the location of the dynamo that supports a planet's magnetic field. For 10 points, name these structures that form as a consequence of iron and nickel being heavier than silicate minerals, concentrating them in the center of a rocky planet.
The Bullen parameter quantifies the deviation of the density distribution of these structures from the AdamsWilliamson equation.
planetary cores [or: outer core, inner core, Earth's core; prompt on: Earth's interior]