Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada.

Many questions remain regarding Earth's earliest crust owing to the rarity of Hadean (>4.03 billion-year-old) rocks and minerals. The Nuvvuagittuq Greenstone Belt (NGB) in Canada may be the only known remnant of Hadean crust, although its age is debated, ranging from ≥3.75 to 4.3 billion years old. Mafic intrusions within this belt were specifically sampled and analyzed to investigate the timing of their magmatic differentiation. Correlations between samarium/neodymium (Sm/Nd) and Nd/Nd and Nd/Nd ratios correspond to ages of 4157 ± 174 and [Formula: see text] million years for the long-lived Sm-Nd and the short-lived Sm-Nd systems, respectively. The age agreement between both extant and extinct radiogenic systems, in rocks related through igneous fractionation, is compelling evidence for preservation of Hadean rocks in the NGB, opening a rare window into Earth's earliest times.