Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 5 June 1998:
Vol. 280. no. 5369, pp. 1580 - 1582
DOI: 10.1126/science.280.5369.1580
Prev | Table of Contents | Next

Reports

Atmosphere-Surface Interactions on Mars: Delta 17O Measurements of Carbonate from ALH 84001 

James Farquhar, Mark H. Thiemens, Teresa Jackson

Oxygen isotope measurements of carbonate from martian meteorite ALH 84001 (delta 18O = 18.3 ± 0.4 per mil, delta 17O = 10.3 ± 0.2 per mil, and Delta 17O = 0.8 ± 0.05 per mil) are fractionated with respect to those of silicate minerals. These measurements support the existence of two oxygen isotope reservoirs (the atmosphere and the silicate planet) on Mars at the time of carbonate growth. The cause of the atmospheric oxygen isotope anomaly may be exchange between CO2 and O(1D) produced by the photodecomposition of ozone. Atmospheric oxygen isotope compositions may be transferred to carbonate minerals by CO2-H2O exchange and mineral growth. A sink of 17O-depleted oxygen, as required by mass balance, may exist in the planetary regolith.

Department of Chemistry, University of California San Diego, 92093-0356, USA. E-mail: jfarquha{at}ucsd.edu (J.F.), mht{at}ucsd.edu (M.H.T.), tjackson{at}ucsd.edu (T.J.)

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Oxygen Cycle of the Terrestrial Planets: Insights into the Processing and History of Oxygen in Surface Environments.
J. Farquhar and D. T. Johnston (2008)
Reviews in Mineralogy and Geochemistry 68, 463-492
   Abstract »    Full Text »    PDF »
Photochemical Mass-Independent Sulfur Isotopes in Achondritic Meteorites.
V. K. Rai, T. L. Jackson, and M. H. Thiemens (2005)
Science 309, 1062-1065
   Abstract »    Full Text »    PDF »
Mass-independent fractionation of oxygen isotopes during thermal decomposition of carbonates.
M. F. Miller, I. A. Franchi, M. H. Thiemens, T. L. Jackson, A. Brack, G. Kurat, and C. T. Pillinger (2002)
PNAS 99, 10988-10993
   Abstract »    Full Text »    PDF »
Stable Isotope Variations in Extraterrestrial Materials.
K. D. McKeegan, K. D. McKeegan, and L. A. Leshin (2001)
Reviews in Mineralogy and Geochemistry 43, 279-318
   Full Text »    PDF »
Mass-Independent Isotope Effects in Planetary Atmospheres and the Early Solar System.
M. H. Thiemens (1999)
Science 283, 341-345
   Abstract »    Full Text »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)