Variability in the uranium isotopic composition of the oceans over glacial-interglacial timescales

Tezer M. Esat*, Yusuke Yokoyama

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    56 Citations (Scopus)


    Uranium-series mass spectrometric analyses of corals from the uplifted last glacial terraces at Huon Peninsula, Papua New Guinea, that grew from 50,000 years ago to 30,000 years ago show systematically low values of 234U/238U, at the time of coral growth, compared with modern corals. When combined with coral data from other studies a systematic trend emerges indicating shifts in the 234U/238U ratio at times of major glacial-interglacial transitions that involve large variations in sea-levels. From last glacial to Holocene, the rate of change in δ234U is approximately 1‰ per thousand years. The variations in the U budget of the oceans appear to be due to accumulation of excess 234U in near shore areas in anoxic and suboxic sediments, in salt marshes and mangroves, in estuaries, and in continental margins during periods of warm climate and high sea-levels. These near-shore areas are exposed during periods of low sea level resulting in rapid oxidation of U into highly soluble phases. The subsequent release of 234U-enriched uranium into the oceans occurs over a sustained period, in step with rising sea-levels.

    Original languageEnglish
    Pages (from-to)4140-4150
    Number of pages11
    JournalGeochimica et Cosmochimica Acta
    Issue number16
    Publication statusPublished - 15 Aug 2006


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