New research confirms that rocks found in Quebec, Canada, specifically in the Nuvvuagittuq Greenstone Belt, are the oldest known rocks on Earth, dating back 4.16 billion years to the Hadean eon. These rocks, characterized by their dark and light green colors with flecks of pink and black, are mainly metamorphosed volcanic rocks of basaltic composition.
Scientists used two different radioactive dating methods (based on samarium and neodymium decay) on intrusions (rocks formed from cooled magma within existing layers) found in the belt, both yielding the 4.16-billion-year age. This finding provides crucial insight into Earth’s earliest crust and geodynamic processes.
Lead researcher Jonathan O’Neil of the University of Ottawa suggests that these rocks, formed partly from the precipitation of ancient seawater, can also reveal details about the composition and temperature of Earth’s primordial oceans, potentially shedding light on the beginnings of life.
While tiny zircon crystals from Australia are even older (4.4 billion years), the Nuvvuagittuq rocks are now the oldest known rocks. This discovery challenges the notion of a perpetually “hellish” Hadean Earth, indicating that by 4.4 billion years ago, a rocky crust and shallow oceans already existed. This new study resolves previous controversies regarding the age of the Nuvvuagittuq rocks by focusing on the intrusions, providing a minimum age for the surrounding volcanic rocks, which are likely even older.
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