Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by McKeegan, K. D. Articles by Leshin, L. A. Search for Related Content GeoRef GeoRef Citation

Stable Isotope Variations in Extraterrestrial Materials

Department of Earth & Space Sciences, University of California, Los Angeles, Los Angeles, California 90095

Laurie A. Leshin

Department of Geological Sciences, Arizona State University, Tempe, Arizona 85287

The first 20% of the full text of this article appears below.

	INTRODUCTION

 
The materials of the planets and the small bodies of the solar system contain a rich record of stable isotope variations in the light elements. As in terrestrial isotope geochemistry, this record reflects physical and chemical processes involving isotopic mixing among different reservoirs as well as fractionations arising in chemical reactions. The processes that influence the isotopic records of extraterrestrial materials range widely in environmental conditions from very high-energy events such as formation of refractory inclusions and chondrules by evaporation, condensation and melting in the solar nebula to lower temperature fluid-rock interactions in asteroids and planets. In addition, however, stable isotope cosmochemistry must consider issues that are beyond the scope of isotope geochemistry. For example, in the terrestrial sphere one may assume the existence of an isotopic reservoir that was originally homogenized during planet formation and the actual isotope compositions of the bulk earth do not need to be known in order to study the differences in stable isotope compositions that have been generated subsequently by various geochemical processes.

This assumption of homogenization cannot be made for extraterrestrial samples, and in fact stable isotopes in meteorites preserve some of the most dramatic evidence for the incomplete nature of the mixing of distinct presolar materials during formation of the solar system. Such ‘isotopic anomalies’ are present in the isotopic distributions of H, C, N, and O on all spatial scales—from microscopic zoning in certain meteoritic minerals to the bulk compositions of asteroids and planets. Thus, some of the isotopic heterogeneities of ‘primitive’ solar system materials represent vestiges of primordial differences that could not be fully erased during the processing of presolar materials. In other cases, isotopic heterogeneities reflect the preservation of unique clues to processes occurring during formation of the solar system and planetary accretion, including early ‘geologic activity’ on planetesimals . . . [Full Text of this Article]

This article has been cited by other articles:

				R. E. Criss and J. Farquhar Abundance, Notation, and Fractionation of Light Stable Isotopes Reviews in Mineralogy and Geochemistry, January 1, 2008; 68(1): 15 - 30. [Abstract] [Full Text] [PDF]

				H. Yurimoto, A. N. Krot, B.-G. Choi, J. Aleon, T. Kunihiro, and A. J. Brearley Oxygen Isotopes of Chondritic Components Reviews in Mineralogy and Geochemistry, January 1, 2008; 68(1): 141 - 186. [Abstract] [Full Text] [PDF]

				K. D. McKeegan, J. Aleon, J. Bradley, D. Brownlee, H. Busemann, A. Butterworth, M. Chaussidon, S. Fallon, C. Floss, J. Gilmour, et al. Isotopic Compositions of Cometary Matter Returned by Stardust Science, December 15, 2006; 314(5806): 1724 - 1728. [Abstract] [Full Text] [PDF]