Retrieving "Density Instabilities" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Mantle Transition Zone

   Linked via "density instabilities"

   The $\text{MTZ}$ serves as a dynamic barrier or "traffic control point" for mantle convection. Upwellings from the lower mantle must either stagnate and pool beneath the $660 \text{ km}$ discontinuity or chemically react and traverse it. The chemical barrier at $660 \text{ km}$ is thought to be slightly less impermeable than the thermal barrier at $410 \text{ km}$, allowing denser material, such as subducting oceanic lithosphere, to enter the [lo…