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Science 19 March 1993:
Vol. 259. no. 5102, pp. 1733 - 1736
DOI: 10.1126/science.259.5102.1733
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Articles

The 18O/16O Ratio of 2-Billion-Year-Old Seawater Inferred from Ancient Oceanic Crust

C. Holmden 1 and K. Muehlenbachs 1

1 Department of Geology, University of Alberta, Edmonton, Alberta, Canada T6G 2E3

An oxygen isotope profile of the 2-billion-year-old Purtuniq ophiolite overlaps with similar profiles of younger ophiolites and the modern oceanic crust. This overlap implies (i) that there was a similar style of seawater—ocean crust interaction during the past 2 billion years; (ii) that the oxygen isotope composition of early Proterozoic seawater was similar to the modern value; (iii) that early Proterozoic sea-floor spreading rates were similar to, or greater than, average modern rates; and (iv) that early Proterozoic carbonate rocks and cherts with low 18O/16O ratios do not reflect global-scale 18O depletion of early Proterozoic oceans.

Submitted on October 5, 1992
Accepted on January 5, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Regional 18O-depletion of Neoproterozoic igneous rocks from Avalonia, Cape Breton Island and southern New Brunswick, Canada.
J. Potter, F.J. Longstaffe, and S.M. Barr (2008)
Geological Society of America Bulletin 120, 347-367
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A Vestige of Earth's Oldest Ophiolite.
H. Furnes, M. de Wit, H. Staudigel, M. Rosing, and K. Muehlenbachs (2007)
Science 315, 1704-1707
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Atmospheric composition and climate on the early Earth.
J. F Kasting and M. T. Howard (2006)
Phil Trans R Soc B 361, 1733-1742
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Palaeoclimates: the first two billion years.
J. F Kasting and S. Ono (2006)
Phil Trans R Soc B 361, 917-929
   Abstract »    Full Text »    PDF »
High Archean climatic temperature inferred from oxygen isotope geochemistry of cherts in the 3.5 Ga Swaziland Supergroup, South Africa.
L. P. Knauth and D. R. Lowe (2003)
Geological Society of America Bulletin 115, 566-580
   Abstract »    Full Text »    PDF »
Ophiolites and global geochemical cycles: implications for the isotopic evolution of seawater.
R. T. Gregory (2003)
Geological Society, London, Special Publications 218, 353-368
   Abstract »    PDF »
Ophiolites as faithful records of the oxygen isotope ratio of ancient seawater: the Solund-Stavfjord Ophiolite Complex as a Late Ordovician example.
K. Muehlenbachs, H. Furnes, H. C. Fonneland, and B. Hellevang (2003)
Geological Society, London, Special Publications 218, 401-414
   Abstract »    PDF »


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