It is thought that the abundance of 40Ar in the atmosphere represents the time-integrated loss of gases from the interior through partial melting in the mantle followed by melt ascent to the surface and gas exsolution. But data now presented reveal two major difficulties with this simple magmatic degassing scenario: that argon is compatible in the major phases of the terrestrial planets and that argon diffusion in these phases is slow at upper-mantle conditions.
- E. Bruce Watson
- Jay B. Thomas
- Daniele J. Cherniak
