Crust Processes and Lanthanide Concentration

Crust-forming processes refer to the geological mechanisms involved in the creation and evolution of the Earth's crust. These processes can lead to the concentration of specific chemical elements in certain geological settings.

Lanthanide Group Properties

The lanthanide group of metals, also known as rare earth elements (REEs), are characterized by their chemical properties. They are primarily lithophile elements, meaning they have a strong affinity for oxygen and tend to occur in oxide minerals within silicate rocks.

Concentration Mechanism

During the cooling and solidification of magma (magmatic differentiation), minerals crystallize sequentially. Lanthanides often exhibit incompatibility during this process. This means they do not readily fit into the crystal structures of common rock-forming minerals that crystallize early (like olivine or pyroxene). As a result, lanthanides tend to remain concentrated in the residual molten material (magma or fluid).

This enrichment becomes particularly significant in the later stages of magmatic differentiation, often leading to their concentration in:

• Felsic igneous rocks (rich in silica).
• Pegmatites (exceptionally coarse-grained igneous rocks).
• Hydrothermal deposits.

Therefore, crust-forming processes like magmatic differentiation naturally concentrate the lanthanide group of metals due to their geochemical behaviour.