The Oldest Rock on Earth?

[Astronuc]

A finding in the Arctic could push the formation of Earth’s crust back by 130 million years
by Elena Kazamia, July 23, 2025

When geologist Hanika Rizo goes into the field she spends most of her time looking at her feet. Simply by trekking across the stark Arctic landscape in Northern Quebec, and paying close attention to the ground, she can glean clues about deep time in the color, texture, and arrangement of the solid outcrops of ancient rock that lie exposed here. Large, bauble-like shapes in the magma—“pillow lava”—speak of contact with water. Finding vestiges of water is always exciting, Rizo says, given that it is one of the requirements for the evolution of life. But the ultimate prize lies in the search for Earth’s oldest rock, which can serve as a window into the embryonic stages of Earth’s formation.

In a publication this summer, together with colleagues, Rizo, a scientist at Carleton University in Ottawa, described rocks at one study site, the Nuvvuagittuq Greenstone Belt, as dating to 4.16 billion years ago, making them some of the oldest rocks ever collected on Earth, possibly the oldest ever to have formed on the planet.

“The chemistry of the rocks tells us that they look very similar to the oceanic crust today,” Rizo says. Their surface is hard and crystalline, made of basalt. Rizo calls them the “first rocks” or the “oldest rocks” interchangeably. Geologists believe that to qualify as a “rock,” a piece of the Earth must be taken from the crust, which first formed once our planet’s mantle stabilized, the upper layer of hot, churned-up magma cooling into a solid shell on which continents and oceans rest.

The gold standard for aging rocks is to look at zirconium crystals, which contain traces of radioactive uranium, whose decay sets the rhythm for measuring time. But the rocks that Rizo and O’Neil work with contain no zirconium. Out of necessity, they chose the rare Earth element Neodymium, instead, which is traditionally used to age asteroids. “If you have a zircon age, no one’s going to dispute it,” Rizo says, but other techniques leave room for doubt.

I was reading about geochronology when reading about some current mineral development projects related to HREEs and zirconium-bearing minerals in the southern hemisphere.

https://en.wikipedia.org/wiki/Nuvvuagittuq_Greenstone_Belt
https://iugs-geoheritage.org/geoheritage_sites/the-hadean-to-eoarchean-nuvvuagittuq-greenstone-belt/

“If [the] Nuvvuagittuq rocks are Hadean, that would make them the only terrestrial rocks from this eon that we know of,” says Martin Guitreau of Clermont Auvergne University, who was not involved with the study.

https://cen.acs.org/physical-chemis...ent-rocks-among-worlds-oldest/103/web/2025/07

 

[Greg Bernhardt]

What do the rocks in the Arctic tell us about when Earth’s crust first formed?

 

[Astronuc]

What do the rocks in the Arctic tell us about when Earth’s crust first formed?

I would hesitate to frame it as "the Earth's crust" forming, but instead consider that regions of the Earth's crust formed (solidified) at different times between 4.7 and 4.0 billion years ago, although it is hypothesized that Earth's surface was molten for some time perhaps between 4.6 to about 4.4 billion years ago. But then one must ponder when did the first region of crust solidify and where, or perhaps first regions of crust.

The article in the OP references, "rocks at one study site, the Nuvvuagittuq Greenstone Belt, as dating to 4.16 billion years ago, making them some of the oldest rocks ever collected on Earth, possibly the oldest ever to have formed on the planet." A much earlier (2008) article indicates older mafic crust (isochron with an age of 4280 +53/-81 million year. ( Neodymium-142 Evidence for Hadean Mafic Crust )

Another article indicates about 4.2 billion years in the (Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada).

Contrast with the 'oldest' rocks found in Western Australia (referenced in Wikipedia):

The oldest dated zircon crystals, enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss terrane of Western Australia, date to 4.404 ± 0.008 Ga. This zircon is a slight outlier, with the oldest consistently dated zircon falling closer to 4.35 Ga—around 200 million years after the hypothesized time of Earth's formation.

See also - https://en.wikipedia.org/wiki/Oldest_dated_rocks

he oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon, which is defined to start with the formation of the oldest intact rocks on Earth.

Archean rocks are exposed on Earth's surface in very few places, such as in the geologic shields of Canada, Australia, and Africa. The ages of these felsic rocks are generally between 2.5 and 3.8 billion years. The approximate ages have a margin of error of millions of years. In 1999, the oldest known rock on Earth was dated to 4.031 ±0.003 billion years, and is part of the Acasta Gneiss of the Slave Craton in northwestern Canada.

Researchers at McGill University found a rock with a very old model age for extraction from the mantle (3.8 to 4.28 billion years ago) in the Nuvvuagittuq greenstone belt on the coast of Hudson Bay, in northern Quebec; the true age of these samples is still under debate, and they may actually be closer to 3.8 billion years old. Older than these rocks are crystals of the mineral zircon, which can survive the disaggregation of their parent rock and be found and dated in younger rock formations.

In the Wikipedia article on the Hadean period

The Hadean is the first and oldest of the four geologic eons of Earth's history, starting with the planet's formation about 4.6 Ga (estimated 4567.30 ± 0.16 Ma (see note 1) set by the age of the oldest solid material in the Solar System—protoplanetary disk dust particles—found as chondrules and calcium–aluminium-rich inclusions in some meteorites about 4.567 Ga) and ending 4.031 Ga, the age of the oldest known intact rock formations on Earth as recognized by the International Commission on Stratigraphy..

See notes 1, 4, 5, 6, 7
1. https://www.episodes.org/journal/view.html?doi=10.18814/epiiugs/2024/024002
4. https://ui.adsabs.harvard.edu/abs/2001GSLSP.190..205D
5. https://pubs.usgs.gov/gip/geotime/age.html
6. Strachan, R.; Murphy, J.B.; Darling, J.; Storey, C.; Shields, G. (2020). "Precambrian (4.56–1 Ga)". In Gradstein, F.M.; Ogg, J.G.; Schmitz, M.D.; Ogg, G.M. (eds.). Geologic Time Scale 2020. Amsterdam: Elsevier. pp. 482–483. doi:10.1016/B978-0-12-824360-2.00016-4. ISBN 978-0-12-824360-2.
7. "Global Boundary Stratotype Section and Point". International Commission of Stratigraphy. Retrieved 21 April 2023. https://stratigraphy.org/gssps/

So, some crustal regions developed (solidified) during the Hadean period (maybe) or during the early (older) Archean period, and possibly during the transition (which is arbitarily defined).

In the Wikipedia article on the Crust

Earth formed approximately 4.6 billion years ago from a disk of dust and gas orbiting the newly formed Sun. It formed via accretion, where planetesimals and other smaller rocky bodies collided and stuck, gradually growing into a planet. This process generated an enormous amount of heat, which caused early Earth to melt completely. As planetary accretion slowed, Earth began to cool, forming its first crust, called a primary or primordial crust. This crust was likely repeatedly destroyed by large impacts, then reformed from the magma ocean left by the impact. None of Earth's primary crust has survived to today; all was destroyed by erosion, impacts, and plate tectonics over the past several billion years.

Since then, Earth has been forming a secondary and tertiary crust, which correspond to oceanic and continental crust, respectively.

Subsequently,

. . . , the bulk of the continental crust is much older. The oldest continental crustal rocks on Earth have ages in the range from about 3.7 to 4.28 billion years and have been found in the Narryer Gneiss terrane in Western Australia, in the Acasta Gneiss in the Northwest Territories on the Canadian Shield, and on other cratonic regions such as those on the Fennoscandian Shield.

If one looks at phase diagrams of complex ceramics, one finds solidi dependent on the composition, and the more components, the more complex the system with some parts solidifying well before others. There is also the partitioning of denser components from lighter components, as well as differences in solubility.

 

[Astronuc]

With regard to Western Australia, I meant to menton the Jack Hills, which "are best known as the source of the oldest material of terrestrial origin found to date: Hadean zircons that formed around 4.404 billion years ago. These zircons have enabled deeper research into the conditions on Earth in the Hadean eon. Potentially biogenic carbon isotope ratios have been identified for graphite embedded within a 4.1 billion-year-old zircon from the site."
https://en.wikipedia.org/wiki/Jack_Hills

The Jack Hills are located in the Narryer Gneiss terrane of the Yilgarn craton, Western Australia, and comprise an 80 kilometres (50 mi) long northeast-trending belt of folded and metamorphosed supracrustal rocks.

The major lithology contains sedimentary siliciclastic rock with minor mafic/ultramafic rocks and banded iron formation (BIF) found in the sequence.

The overall sequence is generally considered to be a granulite gneiss, which has undergone multiple deformations and multiple metamorphic episodes. The protolith age of the Narryer Gneiss terrane is variable, but generally considered to be in excess of 3.6 Ga (billion years).

Siliciclastic rocks are sedimentary rocks composed primarily of silicate minerals like quartz and feldspar, formed from the broken fragments (clasts) of older rocks.

Zircon is Zr silicate ZrSiO₄, perhaps with some lanthanides, (Zr_1–y, REE_y)(SiO₄)_1–x(OH)_4x–y. Hf is often found with Zr, since they are chemically similar from the same group in the Periodic Table.
https://en.wikipedia.org/wiki/Zircon
There is also an interesting article on Hadean Zircons, as distinguished from later zircons.
https://en.wikipedia.org/wiki/Hadean_zircon

I thought the banded iron formations was interesting.
https://en.wikipedia.org/wiki/Banded_iron_formation

I was trying to remember what the evolution of the continents was like. Pangea and Godwana are the most recent, and information seems more readily available. But going back to Archean, one finds Vaalbara "a hypothetical Archean supercontinent consisting of the Kaapvaal craton (in present-day eastern South Africa) and the Pilbara Craton (in present-day north-western Western Australia)."
https://en.wikipedia.org/wiki/Supercontinent#Cycles
https://en.wikipedia.org/wiki/Vaalbara