Origin of rare gases in the Earth

Abstract

Although terrestrial rare gases have elemental abundances similar to those of meteorites (planetary-type rare gases), their Ne and Xe isotopic compositions are quite different which suggests that degassing of meteoritic materials alone cannot explain the atmospheric rare gases. The terrestrial rare gases must contain heavily fractionated rare gases captured by planetesimals during a fragmentation process (planetesimal-type rare gases) as well as the planetary type rare gases.