Noble gases abundances

Noble gas abundances in lunar soils and chondrites, (a) Elemental abundance patterns for trapped solar wind in lunar soils, normalized to solar system abundances, (b) Elemental abundance patterns for planetary trapped noble gases, normalized to solar system abundances. This diagram is intended to illustrate patterns only vertical positions are arbitrary. Modified from Ozima and Podosek (2002). 

Noble gas abundances in planetary atmospheres and Cl carbonaceous chondrites, relative to silicon and solar abundances. After Porcelli and Pepin (2004). 

Table 4.6. Selected data for noble gas abundances (cm3 STP/g) in water...

Figure 5.2 Noble gas abundance (normalized to 36Ar) relative to air abundance. Data are from Table 5.1. The noble gas adsorption curve on pulverized Allende meteorite (Fanale Cannon, 1972) is also shown for comparison.

Dymond, X, Hogan, L. (1973) Noble gas abundance patterns in deep-sea basalts - primordial gases from the mantle. Earth Planet. Sci. Lett., 20, 131-9. 

Ozima, M., Zashu, S., Nitoh, O. (1983) 3He/4He ratio, noble gas abundance and K-Ar dating of diamonds - An attempt to search for the record of early terrestrial history. Geochim. Cosmochim. Acta, 47, 2217-24. 

Zaikowski, A., Schaeffer, O. A. (1979) Solubility of noble gases in serpentine Imphcations for meteoritic noble gas abundance. Earth Planet. Sci. Lett., 45, 141-5. 

One reason is that, at least as far as we know at present, the abundance of identifiable preserved presolar materials in meteorites is low, so that known types of presolar materials do not supply a substantial fraction of the total meteoritic inventory of any elements except for the noble gases. This is another manifestation of the generalization that low noble-gas abundances render prominent some quantitatively small contributions that would be lost in the background sea of other elements. 

Comets are rich in volatile elements, but they probably delivered no more than 10% of Earth s volatile inventory. There are several reasons for this. Comets have a very low impact probability with Earth over their dynamical lifetime ( 10 Levison et al., 2000), limiting the amount of cometary material that Earth could have accreted. In addition, if most of Earth s water was acquired from comets, it seems likely that Earth s noble gas abundances would be higher than observed by several orders of magnitude (Zahnle, 1998). Einally, water measured spectroscopically in comets differs isotopically from that of seawater on Earth, with the cometary D/H ratio being greater by a factor of 2 (Lunine et al., 2000). 

The observed noble-gas abundances and isotopic ratios on Venus are summarized in Tables 3 and 4. The helium mixing ratio is a model-dependent extrapolation of the value measured in Venus upper atmosphere, where diffusive separation of gases occurs. The main differences between Venus and Earth are that Venus is apparently richer in He, Ar, and Kr than the Earth, and the low " Ar/ Ar ratio of — 1.1 on Venus, which is —270 times smaller than on Earth. The low " Ar/ Ar ratio may reflect more efficient solar-wind implantation of Ar in solid grains accreted by Venus and/or efficient early outgassing that then stopped due to the lack of plate tectonics. Wieler (2002) discusses the noble-gas data. Volkov and Frenkel (1993) and Kaula (1999) describe implications of the " Ar/ Ar ratio for outgassing of Venus. 

Thalmann C., Eugster O., Herzog G. F., Klein J., Krahenbiihl U., Vogt S., and Xue S. (1996) History of lunar meteorites Queen Alexandra Range 93069, Asuka 881757, and Yamato 791639 based on noble gas abundances, radionuclide concentrations, and chemical composition. Meteorit. Planet. Sci. 31, 857-868. 

Noble gases and nitrogen in martian meteorites reveal several interior components having isotopic compositions different from those of the atmosphere. Xenon, krypton, and probably argon in the mantle components have solar isotopic compositions, rather than those measured in chondrites. However, ratios of these noble gas abundances are strongly fractionated relative to solar abundances. This decoupling of elemental and isotopic fractionation is not understood. The interior ratio in martian meteorites is similar to chondrites. 

Figure 1 The noble gas abundance patterns of the Earth and Cl chondrites normalized to silicon and the solar composition (reproduced by permission of Mineralogical Society of America from Rev. Mineral. Geochem., 2002, 47, 418).

Matsuda J. and Nagao K. (1986) Noble gas abundance in a deep-sea sediment core from eastern equatorial Pacific. Geochem. J. 20, 71-80. 

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