Rocks in the Nuvvuagittuq Greenstone Belt of Northern Quebec May Be the Oldest Known Rocks on Earth at 4.2-4.3 Billion Years Old

  

   The oldest geological eon is known as the Hadean, named after Hades, the Greek god of the underworld. This is due to the intense heat that was present on the Earth then. The Hadean eon began when the Earth was formed about 4.6 billion years ago and ended about 4.03 billion years ago. It is estimated that the first crust cooled down enough to form rock about 4.35 billion years ago. Very little is known about the earliest rocks in the world and possibly the earliest life forms, in sediment accumulated around a hydrothermal vent in the vicinity of these rocks. These are ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates.

      It has recently been confirmed, or perhaps just strongly suggested, that the oldest known rocks on Earth are located in northern Québec. The oldest terrestrial materials ever dated by scientists are zircon minerals discovered in Western Australia. They formed as early as 4.4 billion years ago, but their host rocks have long eroded away. The zircon crystals are thought to have formed in magmas produced by the melting of sediments deposited at the bottom of an ancient ocean. Research on the Hadean zircons also suggests that the earliest Earth rocks were mafic (rich in magnesium and iron).

     In 2008, some of the researchers of the new paper worked on using Neodymium-142 data to date the rocks of the Nuvvuagittuq greenstone belt (NGB) in northern Quebec, Canada, with suggestions that the rock is 4.28 billion years old. These are also oceanic crustal rocks. The most common rocks in the belt are known as Ujaraaluk rocks, meaning “big old solid rock” in Inuktitut. The suggested age of the rocks has been a matter of debate, with some scientists thinking they are younger, perhaps 3.8 billion years old, putting them in the Archaean eon. However, new research suggests they are older, likely older than 4.2 billion years old.

 

   

Mafic Intrusions Dated by Two Methods of Samarium-Neodymium Isotope Dating Show that They are about 4.16 Billion Years Old, Which Means the Rock They Intruded is Older

     In 2017, the researchers collected intrusive metagabbro rocks that intrude the existing greenstone belt rocks. The simple fact that igneous intrusive rocks must be younger than the rocks they intrude gives an age limit to the host rocks.  According to the scientists:

“We combined our field observations with petrology, geochemistry, geochronology and applied two independent samarium-neodymium age dating methods, dating techniques used to assess the absolute ages of magmatic rocks, before they became metamorphic rocks. Both assessments yielded the same result: the intrusive rocks are 4.16 billion years old.”

     As noted, the scientists used long- and short-lived samarium-neodymium isotope systems to determine when the rocks first crystallized. Also, as noted, there is still debate about the age of the rocks. The new dates given for the mafic metagabbro intrusive rocks, however, suggest that the older Hadean age is correct, as explained below by the scientists:

“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.”

 

   

 

References:

 

The oldest rocks on Earth are more than four billion years old.  Hanika Rizo and Jonathan O’Neil. The Conversation. July 6, 2025. The oldest rocks on Earth are more than four billion years old

Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada. C. Sole, J. O’Neil, H. Rizo, J.-L. Paquette, D. Benn, and J. Plakholm. Science. 26 Jun 2025. Vol 388, Issue 6754. pp. 1431-1435. Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada | Science

Evidence for early life in Earth’s oldest hydrothermal vent precipitates. Matthew S. Dodd, Dominic Papineau, Tor Grenne, John F. Slack, Martin Rittner, Franco Pirajno, Jonathan O’Neil & Crispin T. S. Little. Nature. volume 543, pages60–64 (March 2, 2017). Evidence for early life in Earth’s oldest hydrothermal vent precipitates | Nature

Neodymium-142 Evidence for Hadean Mafic Crust. Jonathan O'Neil, Richard W. Carlson, Don Francis, and Ross K. Stevenson. Science. 26 Sep 2008. Vol 321, Issue 5897. pp. 1828-1831. Neodymium-142 Evidence for Hadean Mafic Crust | Science