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Nuvvuagtiiuq rock suite

Rocks of Hadean

Four diferent paragneiss from Nuvvuagittuq suite

Aged from 4.03Ga to 4.28Ga !!!

Specimens here have been collected ollected by the team of the Earth and Planetary Science Department of the McGill University, Montreal, Quebec, Canada (traded for meteorites)

Published in Science, 26 september 2008, Vol 321, pages 1828-1831

Thesis Abstract :

The Nuvvuagittuq greenstone belt is an Eoarchean/Hadean succession preserved along the eastern coast of Hudson Bay in the Northeastern Superior Province, Quebec, Canada. It is essentially composed of three major lithological units: 1) mafic cummingtonite-amphibolite, known as the "faux-amphibolite", which is the dominant lithology of the belt, 2) ultramafic and mafic sills that intrude the faux-amphibolite, and 3) chemical sedimentary rocks comprising a banded iron formation (BIF) and a silica-formation. The faux-amphibolite has a basaltic to andesitic composition. It is composed of variable proportions of cummingtonite + biotite + quartz, ± plagioclase ± garnet ± anthophyllite ± cordierite and ranges from cummingtonite amphibolite to garnet-biotite schist. Some rocks from the Nuvvuagittuq greenstone belt have lower 142Nd /144Nd ratios than the terrestrial standard (epsilon142Nd = -0.07 to -0.15). The 142Nd/144Nd ratios for the faux-amphibolite correlate positively with their Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of 4280 +53 –81 million years. The 4.28 Ga faux-amphibolite is intruded by highly deformed gabbro sills yielding a 147Sm-143Nd isochron with a slope corresponding to an age of 4023 ± 110 Ma. The Nuvvuagittuq greenstone belt also comprises 3.8 Ga felsic bands and is surrounded by 3.66 Ga tonalite interpreted to have been produced by the melting of the older mafic faux-amphibolite. The Nuvvuagittuq greenstone belt thus represents an Eoarchean/Hadean crustal section comprising the oldest rocks preserved on Earth. The 4.28 Ga faux-amphibolite is divided into a high-Ti group and a low-Ti group with co-genetic ultramafic sills and separated by a BIF/silica-formation. At the base of the sequence, the high-Ti faux-amphibolite is basaltic in composition and has "tholeitic"

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Each lot is composed by :

Specimen 1 : Garnet-bearing "faux-amphibolite" oldest rock (4.28Ga)

Specimen 2 : Cummingtonite-rich "faux-amphibolite" oldest rock (4.28Ga)

Specimen 3 : Fe-rich amphibolite, intrusive Hadean age rock (4.03Ga)

Specimen 4 : Fe-rich garnet amphibolite, intrusive Hadean age rock (4.03Ga)