Outgassing

The term “degassing” (or outgassing) refers to the process of release of atmospheric gas present in the mantle or in magmas when its amount exceeds the solubility limit. The distribution of volatile elements, such as carbon dioxide (CO₂) or argon (Ar), between a solid (or a liquid) and a gas, reaches equilibrium when further transfer from one phase to another entails an overall increase of the system energy. Henry’s law states that, at equilibrium, the amount of volatile element dissolved is proportional to its partial pressure in the gas phase at a specific temperature. Outgassing of planetary mantles by volcanic activity is viewed as a major pathway to formation of secondary atmospheres on telluric planets.

 Earth's Atmosphere, Origin and Evolution of

 Earth, Formation and Early Evolution

 Mantle Volatiles

 Noble Gases