Earth evolution models

Ozima, M., Igarashi, G. (2000) The Primordial noble gases in the Earth A key constraint on Earth evolution models. Earth Planet. Sci. Lett., 176, 219-32. 

One implication of Earth - degassing models of metallogenesis is that there should be links between the formation of the Earth s resources, secular changes in architecture and geochemistry of the planet over some 4.5 billion years of evolution and phenomena such as mass extinction events, global anoxia, and atmospheric evolution. 

Hamano, Y., Ozima, M. (1978) Earth atmosphere evolution model based on Ar isotopic data. In Terrestrial Rare Gases. Jr. E. C. Alexander, M. Ozima, Eds., pp. 155-72. Tokyo Center... 

Ozima, M., Alexander, Jr., E. C. (1976) Rare gas fractionation patterns in terrestrial samples and the earth-atmosphere evolution model. Rev. Geophys. Space Phys., 14, 385-90. 

Ozima, M., Kudo, K. (1972) Excess argon in submarine basalts and an earth-atmosphere evolution model. Nature Phys. Sci., 239, 23-4. 

Ozima M. (1975) Ar isotopes and Earth-atmosphere evolution models. Geochim. Cosmochim. Acta 39, 1127-1134. 

Venus. Venus is characterized only by the immensely valuable but still incomplete and relatively imprecise reconnaissance data from the Pioneer Venus and Venera spacecraft missions of the late 1970s. Additional in situ measurements, at precisions within the capabilities of current spacecraft instrumentation, are now necessary to refine atmospheric evolution models. Unfortunately, the possibilities of documenting the volatile inventories of the interior of the planet are more remote. A significant question that must be addressed is whether nonradiogenic xenon on Venus is compositionally closer to SW-Xe (as seen on Mars) or to the U-Xe that is seen on the Earth and so is expected to have been present within the inner solar system. Also, the extent of xenon fractionation will be an important parameter for hydrodynamic escape models if intense solar EUV radiation drove hydrodynamic escape on the Earth, it would also impact Venus, while losses from the Earth driven by a giant impact would not be recorded there. 

This review will first examine the controls on Earth s modern atmosphere, to give a uniformi-tarian basis then consider parallel worlds. Next, models of Earth evolution are built, on unifor-mitarian grounds by looking at the early abiotic Earth and by considering biogeochemical processes in the Archaean. To provide experimental constraint, the Belingwe area is examined in detail. The operation of the Archaean atmosphere is discussed then the links between air and ocean, and the links with the mantle and interior. Lastly, the overall controls are considered. 

Current results of this exercise, using the Xe component compositions listed in Table 1, are reviewed in Pepin (2000). Applied to Earth, a modeling procedure involving derivation of fractionation relationships between nonradiogenic terrestrial and meteoritic Xe compositions simultaneously identifies a composition named U-Xe as primordial Xe, and establishes the presence of an atmospheric Xe component due principally to fission of extinct as noted earlier in this chapter. Hydrodynamic escape of U-Xe leaves its fractionated residue on Earth. Evolution of atmospheric Xe from this early composition to its present isotopic state by subsequent degassing of fission and radiogenic... 

Halliday AN, Davidson JP, Holden P, DeWolf C, Lee D-C, Fitton JG (1990) Trace-element fractionation in plumes and the origin of HIMU mantle beneath the Cameroon line. Nature 347 523-528 Hamano Y, Ozima M (1978) Earth-atmosphere evolution model based on Ar isotopic data. In Alexander EC, Ozima M (eds) Terrestrial Rare Gases. Center for Academic Publications Japan, Tokyo, p 155-171 Hamelin B, Dupre B, Allegre C-J (1984) Lead-strontium isotopic variations along the East Pacific Rise and the Mid-Atlantic Ridge a comparative study. Earth Planet Sci Lett 67 340-350 Hanan BB, Graham DW (1996) Lead and helium isotope evidence from oceanic basalts for a common deep source of mantle plumes. Science 272 991-995... 

Nier AO, Hayden JL (1971) A miniature Mattauch-Herzog mass spectrometer for the investigation of planetary atmospheres. Inti J Mass Spectrom Ion Phys 6 339-346 Nier AO, McElroy MB (1977) Composition and stmctuie of Mars upper atmosphere results from the neutral mass spectrometers on Viking 1 and 2. J Geophys Res 82 4341-4349 Ott U (2002) Noble gases in meteorites- trapped components. Rev Mineral Geochem 47 71-100 Ozima M, Kudo K (1972) Excess argon in submarine basalts and an earth-atmosphere evolution model. Nature Phys Sci 239 23-24... 

Method Theoretically, the best way to correct the data for common-Pb is to use the only nonradiogenic Pb isotope, Pb, because it involves the fewest assumptions. The main assumption is related to the knowledge of the common-Pb composition at the time of the closure of the system, which presupposes that an estimate of this time is available and to refer to a model of earth evolution [21]. 

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