Neodymium-142 Evidence for Hadean Mafic Crust

@article{ONeil2008Neodymium142EF,
  title={Neodymium-142 Evidence for Hadean Mafic Crust},
  author={Jonathan O’Neil and Richard W. Carlson and Don Francis and Ross K. Stevenson},
  journal={Science},
  year={2008},
  volume={321},
  pages={1828 - 1831}
}
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 (ϵ142Nd = –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 \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin… 

Comment on “Neodymium-142 Evidence for Hadean Mafic Crust”

It is argued 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.

142Nd evidence for an enriched Hadean reservoir in cratonic roots

The mantle sampled by magmatism since 3.6 Gyr ago may be biased towards a depleted composition that would be balanced by relatively more enriched reservoirs that are ‘hidden’ in Hadean crust, the D′′ layer of the lowermost mantle or, as it is proposed here, also within the roots of old cratons.

Hadean silicate differentiation preserved by anomalous 142Nd/144Nd ratios in the Réunion hotspot source

The results show that Réunion magmas tap into a particularly ancient, primitive source compared with other volcanic hotspots, offering insight into the formation and preservation of ancient heterogeneities in Earth’s interior.

Direct evidence for crust-mantle differentiation in the late Hadean

Constraints on the evolution of the silicate Earth between 4.5 and 3.8 billion years ago are limited by the scarcity of pristine geological material from that period. The geodynamic evolution of the

Response to Comment on “Neodymium-142 Evidence for Hadean Mafic Crust”

Andreasen and Sharma raise concerns about the neodymium-142 data and age that we reported for rocks from the Nuvvuagittuq greenstone belt in Quebec, Canada. We agree that the issue of accurate mass

Neodymium isotopes and evolution of early terrestrial crust

Geological records of the earliest history of the Earth are rare; rocks older than 3700 Ma comprise only a few percent of continental surfaces. Evidence is mounting, however, that vestiges of

Potassic, high-silica Hadean crust

Analysis of strontium isotopic composition of apatite inclusions in zircons from Nuvvuagittuq, Canada, shows that its protolith had formed a high Rb/Sr ratio reservoir by at least 4.2 Ga, which implies that the early crust had a broad range of igneous rocks, extending from mafic to highly silicic compositions.
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