Planetary differentiation

Iron, the most common element that is likely to form a very dense molten metal phase, tends to congregate towards planetary interiors.

Diapirs of molten low-density silicate rocks such as granite are abundant in the Earth's upper crust.

The hydrated, low-density serpentinite formed by alteration of mantle material at subduction zones can also rise to the surface as diapirs.

For example, the hafnium-tungsten system demonstrates the decay of two unstable isotopes and possibly forms a timeline for accretion.

Heating due to radioactivity, impacts, and gravitational pressure melted parts of protoplanets as they grew toward being planets.

The compositions of some meteorites (achondrites) show that differentiation also took place in some asteroids (e.g. Vesta), that are parental bodies for meteoroids.

[3] In the outer Solar System, a similar process may take place but with lighter materials: they may be hydrocarbons such as methane, water as liquid or ice, or frozen carbon dioxide.

Core formation utilizes several mechanisms in order to control the movement of metals into the interior of a planetary body.

[3] Examples include percolation, diking, diapirism, and the direct delivery of impacts are mechanisms involved in this process.

[3] A sufficient amount of pressure must be met for a metal to successfully travel through the fracture toughness of the surrounding material.

The size of the metal intruding and the viscosity of the surrounding material determines the rate of the sinking process.

[3] The direct delivery of impacts occurs when an impactor of similar proportions strikes the target planetary body.

Based on the studies of short lived radionuclides, the results suggest that core formation process occurred during an early stage of the solar system.

However, in most cases, accretion requires multiple collisions of similar sized objects to have a major difference in the planet's growth.