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Retraction of Baldini et al., Science 296 (5576) 2203-2206.

Science 10 August 2007:
Vol. 317. no. 5839, p. 748
DOI: 10.1126/science.317.5839.748b
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Letters

Retraction of an Interpretation

In the Report "Structure of the 8200-year cold event revealed by a speleothem trace element record" (1), we presented a 7762-μm-long ion probe trace element traverse chosen to include the 8200-year event as detected in a previously published laser ablation oxygen isotope study from the same stalagmite (2). The oxygen isotope anomaly was distinct and dropped 8‰ below baseline values to a low value for the entire Holocene of -12‰ and was reproducible on a reverse track. However, recent reanalysis of the calcite believed to contain the oxygen isotope anomaly suggests that the anomaly was probably an analytical artifact possibly caused by laser ablation-induced fracturing during the original analysis (3). Consequently, without the original delta18O "marker," the precise location in the stalagmite of calcite deposited during the 8200-year event is uncertain.

The trace element data in this Report, previously believed to correspond precisely with the entire 8200-year event, are now believed to represent the hydrological and bioproductivity response in western Ireland to a cold/dry event of uncertain provenance and intensity. The U-Th-derived dates of the event correspond approximately with the 8200-year event in Greenland ice cores, but without the additional guidance of the delta18O anomaly, the precise timing in relation to the 8200-year event is now somewhat ambiguous. Unfortunately, it is now unlikely that the approximately 114-year duration ion probe track coincides with the entire 8200-year event (if at all); thus, the ~37-year estimate derived for its duration is probably no longer accurate. However, the trace element data remain robust and are interpreted as reflecting colder and drier conditions in western Ireland, followed by the return to more maritime conditions at the end of the first-order trace element anomaly. Additionally, the novel application of annual trace element cycles to build a high-resolution chronology and reconstruct paleoseasonality remains unchanged.

James U. L. Baldini
Department of Earth Sciences
Durham University
South Road
Durham DH1 3LE, UK

Frank McDermott
Department of Geology
University College Dublin
Dublin 4, Ireland

Ian J. Fairchild
School of Geography
Earth and Environmental Science
University of Birmingham
Birmingham B15 2TT, UK

References

  1. J. U. L. Baldini, F. McDermott, I. J. Fairchild, Science 296, 2203 (2002).
  2. F. McDermott, D. P. Mattey, C. Hawkesworth, Science 294, 1328 (2001).
  3. I. J. Fairchild et al., Earth Sci. Rev. 75, 105 (2006).




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