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Science 17 July 2009:
Vol. 325. no. 5938, p. 267
DOI: 10.1126/science.1169604
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Technical Comments

Comment on "Neodymium-142 Evidence for Hadean Mafic Crust"

Rasmus Andreasen1,* and Mukul Sharma2

O'Neil et al. (Reports, 26 September 2008, p. 1828) presented neodymium-142 data for rocks from northern Quebec, Canada, and suggested that these rocks may represent the oldest preserved crustal section on Earth. We argue that the age of the rocks is based on a spurious correlation between rocks that are probably not co-genetic and negative 142Nd anomalies that may be the result of an analytical artifact.

1 Imperial College London, Department of Earth Science and Engineering, South Kensington SW7 2AZ, UK.
2 Dartmouth College, Department of Earth Sciences, Hanover, NH 03755, USA.

* To whom correspondence should be addressed. E-mail: r.andreasen{at}imperial.ac.uk

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