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Science 26 September 2008:
Vol. 321. no. 5897, pp. 1828 - 1831
DOI: 10.1126/science.1161925

Reports

Neodymium-142 Evidence for Hadean Mafic Crust

Jonathan O'Neil,1* Richard W. Carlson,2 Don Francis,1 Ross K. Stevenson3

Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower 142Nd/144Nd ratios than the terrestrial standard ({epsilon}142Nd = –0.07 to –0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of Formula million years. These rocks thus sample incompatible-element-enriched material formed shortly after Earth formation and may represent the oldest preserved crustal section on Earth.

1 Earth and Planetary Sciences Department, McGill University, 3450 University Street, Montreal, Quebec, H3A 2A7, Canada.
2 Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015, USA.
3 GEOTOP (Centre de recherche en géochemie et géodynamique), Université du Québec à Montréal, Post Office Box 8888, Succursale Centre-ville, 210, Président-Kennedy Avenue, Montreal, Quebec H3C 3P8, Canada.

* To whom correspondence should be addressed. E-mail: oneil_jo{at}eps.mcgill.ca

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