Solar Noble Gases

To resolve the primordial terrestrial noble gas, it would be useful to examine major noble gas reservoirs in the early solar system, which could have supplied noble gases to the Earth. As we discussed in Chapter 3, two major noble gas components occur very widely in the solar system and can be a potential source for the terrestrial noble gas. They are solar noble gas (representative of the sun), which is generally assumed to be best represented by solar wind noble gas implanted on Al-foil target plates on the moon (elemental ratio) and on lunar breccia (isotopic ratio) (e.g., Ozima et al., 1998), and Q phase noble gas (see Wieler, 1994, for a review), which occurs very widely in various chondrites. Next we will compare the bulk Earth noble gas, which we assume to be represented by atmospheric noble gas with these two major noble gas components in the solar system. 

Comparing Q noble gas and solar noble gas (Section 7.3, and also Sections 3.2 and 3.3), we showed that they may be related to each other by Rayleigh distillation. 

The specific model for Earth formation is the crucial assumption in this absorption scenario. If Earth formation proceeded in nebula-free space as was originally postulated by Safronov (1969) and henceforth advocated by various researchers (e.g., Levy Lunine, 1993), the absorption scenario must be abandoned. Also, the Mizuno model predicts that Ne as well as other noble gases in the mantle should have solar noble gas isotopic compositions. However, as we discussed in Chapter 5, the currently available observational data on mantle noble gases show nonsolar isotopic compositions, arguing against the Mizuno model. 

Honda, M., McDougall, I., Patterson, D. B., Doulgeris, A., Clague, D. A. (1991a) Possible solar noble gas component in Hawaiian basalts. Nature, 349, 149-51. 

Wider R. (1998) The solar noble gas record in lunar samples and meteorites. Space Sci. Rev. 85, 303-314. 

Hofmann AW (1997) Mantle geochemistry The message from oceanic volcanism. Nature 385 219-229 Honda M, McDougall I, Patterson DB, Donlgeris A, Clagne DA (1991) Possible solar noble-gas component in Hawaiian basalts. Natnre 349 149-151... 

Honda M, McDougall I, Patterson DB, Doulgeris A, Clague DA (1991) Possible solar noble gas component... 

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