Nuvvuagittuq greenstone belt
The Nuvvuagittuq greenstone belt is mainly composed of cummingtonite-plagioclase-biotite-garnet mafic amphibolites called the Ujaraaluk unit (formerly called the "Faux-amphibolite" due to its unusual color).
There are few detailed maps of the region, but this belt is only known to occupy a small part of Hudson's Bay
Rocks from the Ujaraaluk unit have a neodymium-142 isotopic signature that can only be acquired in the Hadean, prior to 4 billion years ago. This isotopic tool has been used to date these rocks at up to 4.4 billion years old.
The mafic rocks from the Nuvvuagittuq belt are interpreted to be volcanic rocks that were hydrothermally altered and includes a banded iron formation between a lower basalt and an upper unit which includes basalt and andesite.
In 2014, a detailed geochemical analysis, revealing layered gradients of ytterbium and niobium, suggested that this formation consists of pillow lavas from a tectonic subduction zone, similar to the modern Mariana trench.
- O'Neil et al., Formation age and metamorphic history of the Nuvvuagittuq Greenstone Belt, Precambrian Research, V. 220-221 (2012) pp. 23 - 44 abstract
- Implications of the Nuvvuagittuq “faux-amphibolite” for the formation of Earth’s early crust, American Geophysical Union, Fall Meeting 2009
- O'Neil et al., Implications of the Nuvvuagittuq Greenstone Belt for the Formation of Earth’s Early Crust, Journal of Petrology, Vol. 52 (2011) pp. 985 - 1009
- Regan, Mark, The Dawn of Plate Tectonics, Science NOW, 19 February 2014
- S. Turner et al., Geochemical Fingerprinting of the Earth's Oldest Rocks, Geology, vol. 42 (2014) pp. 175-176
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