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Reuters
26-06-2025
- Science
- Reuters
Rocks in Canada's Quebec province found to be the oldest on Earth
June 26 (Reuters) - Along the eastern shore of Hudson Bay in Canada's northeastern province of Quebec, near the Inuit municipality of Inukjuak, resides a belt of volcanic rock that displays a blend of dark and light green colors, with flecks of pink and black. New testing shows that these are Earth's oldest-known rocks. Two different testing methods found that rocks from an area called the Nuvvuagittuq Greenstone Belt in northern Quebec date to 4.16 billion years ago, a time known as the Hadean eon. The eon is named after the ancient Greek god of the underworld, Hades, owing to the hellish landscape thought to have existed then on Earth. The research indicates that the Nuvvuagittuq Greenstone Belt harbors surviving fragments of Earth's oldest crust, the planet's outermost solid shell. The Nuvvuagittuq rocks are mainly metamorphosed volcanic rocks of basaltic composition. Metamorphosed rock is a kind that has been changed by heat and pressure over time. Basalt is a common type of volcanic rock. The rocks tested in the new study were called intrusions. That means they formed when magma - molten rock - penetrated existing rock layers and then cooled and solidified underground. The researchers applied two dating methods based on an analysis of the radioactive decay of the elements samarium and neodymium contained in them. Both produced the same conclusion - that the rocks were 4.16 billion years old. Future chemical analyses of these rocks could provide insight into Earth's conditions during the Hadean, a time shrouded in mystery because of the paucity of physical remains. "These rocks and the Nuvvuagittuq belt being the only rock record from the Hadean, they offer a unique window into our planet's earliest time to better understand how the first crust formed on Earth and what were the geodynamic processes involved," said University of Ottawa geology professor Jonathan O'Neil, who led the study published on Thursday in the journal Science, opens new tab. The rocks may have formed when rain fell on molten rock, cooling and solidifying it. That rain would have been composed of water evaporated from Earth's primordial seas. "Since some of these rocks were also formed from precipitation from the ancient seawater, they can shed light on the first oceans' composition, temperatures and help establish the environment where life could have begun on Earth," O'Neil said. Until now, the oldest-known rocks were ones dating to about 4.03 billion years ago from Canada's Northwest Territories, O'Neil said. While the Nuvvuagittuq samples are now the oldest-known rocks, tiny crystals of the mineral zircon from western Australia have been dated to 4.4 billion years old. The Hadean ran from Earth's formation roughly 4.5 billion years ago until 4.03 billion years ago. Early during this eon, a huge collision occurred that is believed to have resulted in the formation of the moon. But by the time the Nuvvuagittuq rocks formed, Earth had begun to become a more recognizable place. "The Earth was certainly not a big ball of molten lava during the entire Hadean eon, as its name would suggest. By nearly 4.4 billion years ago, a rocky crust already existed on Earth, likely mostly basaltic and covered with shallow and warmer oceans. An atmosphere was present, but different than the present-day atmosphere," O'Neil said. There had been some controversy over the age of Nuvvuagittuq rocks. As reported in a study published in 2008, previous tests on samples from the volcanic rock layers that contained the intrusions yielded conflicting dates - one giving an age of 4.3 billion years and another giving a younger age of 3.3 to 3.8 billion years. O'Neil said the discrepancy may have been because the method that produced the conclusion of a younger age was sensitive to thermal events that have occurred since the rock formed, skewing the finding. The new study, with two testing methods producing harmonious conclusions on the age of the intrusion rocks, provides a minimum age for the volcanic rocks that contain these intrusions, O'Neil added. "The intrusion would be 4.16 billion years old, and because the volcanic rocks must be older, their best age would be 4.3 billion years old, as supported by the 2008 study," O'Neil said.
Daily Mail
26-05-2025
- Science
- Daily Mail
Earth's core holds a vast reservoir of gold - and it's leaking towards the surface
You might think the Earth's largest gold reserves are locked up at Fort Knox. But Earth's core is rich with the precious metal – and it's slowly making its way up towards us, according to a new study. Ultra-high precision analysis of volcanic rocks show Earth's core is 'leaking' into rocks above. And it's bringing gold and other precious metals with it. Dr Nils Messling, at Göttingen University's Department of Geochemistry, said: 'When the first results came in, we realised that we had literally struck gold! 'Our data confirmed that material from the core, including gold and other precious metals, is leaking into the Earth's mantle above.' More than 99.999 per cent of Earth's stores of gold lie buried under 2,900km (1,800 miles) of solid rock, locked away within the Earth's metallic core and far beyond the reaches of humankind. The team analysed rocks on the island of Hawaii, specifically looking at traces of the precious metal ruthenium (Ru). Compared to the Earth's rocky mantle, the metallic core contains a slightly higher abundance of a particular isotope called 100Ru. That's because this ruthenium, which was locked in the Earth's core together with gold and other precious metals when it formed 4.5 billion years ago, came from a different source than the scarce amount that is contained in the mantle today. These differences are so small it was impossible to detect them in the past. Now, new procedures developed by the research team made it possible to analyse them. The unusually high 100Ru levels they found in lava on the Earth's surface can only mean that these rocks ultimately originated from the boundary between the Earth's core and mantle. Professor Matthias Willbold, who also worked on the study, said: 'Our findings not only show that the Earth's core is not as isolated as previously assumed. 'We can now also prove that huge volumes of super-heated mantle material – several hundreds of quadrillion metric tonnes of rock – originate at the core-mantle boundary and rise to the Earth's surface to form ocean islands like Hawaii.' The findings mean that at least some of the precarious supplies of gold and other precious metals that we currently have access to may have come from the Earth's core. It's believed that when the Earth was forming, gold and other heavier elements sank down into its interior. As a result, the majority of gold we currently have access to on the Earth's surface was delivered here by meteors bombarding our planet. Other elements that could currently be 'leaking' out of the core include palladium, rhodium and platinum. Despite the findings it's unlikely these precious metals are emerging at a particularly fast rate. It would also be impossible to drill down to where the Earth's core begins – approximately 2,900km (1,800 miles) - to access the gold contained down there. The findings were published in the journal Nature. Earth has an unusually high proportion of precious metals near the surface, which is surprising, as they would usually be expected to settle down near the core of the planet. Until now, this has been explained by the 'late veneer' theory, which suggests that foreign objects hit Earth, and in the process deposited the precious metals near the surface. New computer simulations from the Tokyo Institute of Technology took into account the metal concentrations on Earth, the moon and Mars, and suggests that a huge collision could have brought all the precious metals to Earth at once. The researchers believe that this happened before the Earth's crust formed – around 4.45 billion years ago. The findings suggest that Earth's history could have been less violent than previously thought.
The Independent
23-05-2025
- Science
- The Independent
Scientists stunned to find Earth's core leaking gold and other precious metals
A first-of-its-kind analysis of Hawaiian volcanic rocks has revealed that the Earth 's core is leaking gold and other precious metals into the surface above. Over 99.99 per cent of the Earth's deposits of gold and precious metals like Ruthenium lie locked away in its metallic core beneath 3,000km of solid rock and far beyond the reach of humankind. The precious metals were locked in the core when the planet formed 4.5bn years ago. 'Precious metals such as ruthenium are highly concentrated in the metallic core but extremely depleted in the silicate mantle,' researchers said in the analysis published on Wednesday in the journal Nature. The researchers, using new techniques, detected Ruthenium in volcanic rocks on the Earth's surface in levels that indicated their origin lay in the core-mantle boundary. The study found that volcanic basalt rocks from Hawaii had a much higher concentration of precious metals than the mantle did. 'Our data confirms that material from the core, including gold and other precious metals, is leaking into the mantle above,' study co-author Nils Messling from the University of Göttingen said. 'When the first results came in, we realised that we had literally struck gold!' The findings reveal that the Earth's core is not as isolated as previously believed. Once thought inaccessible, material from the core is ejected towards the surface during volcanic eruptions and could be studied in the future through such leaks. Forms of Ruthenium could act as a new tracer to further study core-mantle interaction, the researchers said. The new analysis shows that several hundred quadrillion metric tonnes of superheated material from near the core-mantle boundary rise to the Earth's surface to form ocean islands like Hawaii. This also means that at least some of the world's supplies of gold and other precious metals that we rely on now come from the core. However, researchers said, it remained to be seen whether the core-leaking process observed in the study existed in the past as well. 'Our findings open up an entirely new perspective on the evolution of the inner dynamics of our home planet,' the study noted.
