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Summary: Primary U distribution in scleractinian corals and its
implications for U series dating
Laura F. Robinson
California Institute of Technology, MS 100-23, 1200 East California Boulevard, Pasadena, California 91125, USA
Now at Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institute, Woods Hole,
Massachusetts 02543, USA. (lrobinson@whoi.edu)
Jess F. Adkins, Diego P. Fernandez, Donald S. Burnett, S.-L. Wang, Alexander C. Gagnon,
and Nir Krakauer
California Institute of Technology, MS 100-23, 1200 East California Boulevard, Pasadena, California 91125, USA
[1] In this study we use microsampling techniques to explore diagenetic processes in carbonates. These
processes are important as they can affect the accuracy of U series chronometry. Fission track maps of
deep-sea scleractinian corals show a threefold difference between the minimum and maximum [U] in
modern corals, which is reduced to a factor of 2 in fossil corals. We use micromilling and MC-ICP-MS to
make detailed analyses of the [U] and d234
Uinitial distributions in corals from 218 ka to modern. Within
each fossil coral we observe a large range of d234
Uinitial values, with high d234
Uinitial values typically
associated with low [U]. A simple model shows that this observation is best explained by preferential
movement of alpha-decay produced 234
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