Neodymium-142 evidence for hadean mafic crust

Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower Nd-142/Nd-144 ratios than the terrestrial standard (epsilon Nd-142 = - 0.07 to - 0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a Sm-146-Nd-142 isochron with an age of 4280(-81)(vertical bar) (53) 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.