Latest news with #ancientrocks
Yahoo
8 hours ago
- Science
- Yahoo
Earth's oldest rocks date back 4.16 billion years
While rocks are not exactly living things, they are not immune to Earth's fury. Ever-shifting tectonic plates constantly devour and pulverize them, or some rocks get turned into diamonds from the immense pressure underneath our feet. While life on Earth has almost been wiped out at least five times, some rocks pre-date life on Earth and have stood the ultimate test of time. Gray rocks uncovered in northern Nunavik, Quebec, Canada may be the ultimate primordial find. The stones date back 4.16 billion years to the Hadean era and are the oldest known rocks on the planet. They are described in a study published June 26 in the journal Science. Earth was a ball of molten lava when it first formed about 4.5 billion years ago. Scientists originally believed that Earth's first eon–the Hadean–ended when the first rocks formed. A golden spike–a geological marker indicates a boundary between time periods–that ended the Hadean eon is about 4.03 billion years old and located in Canada's Northwest Territories. The Nuvvuagittuq Greenstone Belt, located over 1,000 miles southeast of the Hadean's golden spike, has long been known for its ancient rocks. However, researchers have disagreed about the true age of these plains of gray stone that line the eastern shore of Hudson Bay in Quebec. In 2008, researchers proposed that these rocks dated back 4.3 billion years. Other scientists using a different dating method contested, saying that contaminants from ages ago were altering the rocks' age and they were only 3.8 billion years old. 'For over 15 years, the scientific community has debated the age of volcanic rocks from northern Quebec,' study co-author and University of Ottawa geologist Jonathan O'Neill said in a statement. 'Our previous research suggested that they could date back 4.3 billion years, but this wasn't the consensus.' [ Related: How old is Earth? It's a surprisingly tough question to answer. ] This new study used rock samples from a different part of the Nuvvuagittuq Greenstone Belt. The samples were collected in 2017 near the municipality of Inukjuak, Nunavik, by study co-author Christian Sole, while was completing his Master's degree. To determine the age of these rocks, the team combined geochemistry with petrology–a branch in geology that focuses on the composition, texture, and structure of rocks and the conditions under which they form. They also applied two radiometric dating methods to see how radioactive isotopes of the elements samarium and neodymium change over time. [ Related: Ancient rocks tie Roman Empire's collapse to a mini ice age. ] They found that both chronometers indicated that the rocks are 4.16 billion years old. Since the planet Earth formed roughly 4.5 billion years ago, this puts the rocks within a few hundred million years of our planet's earliest day–somewhat close in geological time. Typically, primordial rocks like these are melted and used over and over again by Earth's moving tectonic plates. While scientists uncovered some 4 billion-year-old rocks in Canada's Acasta Gneiss Complex, finding them at the surface is not common. According to the team, this discovery opens a unique window on the early Earth, potentially offering up clues to its existence. 'Understanding these rocks is going back to the very origins of our planet,' O'Neill said. 'This allows us to better understand how the first continents were formed and to reconstruct the environment from which life could have emerged.'
Forbes
21 hours ago
- Science
- Forbes
New Study Confirms That The Oldest Rocks On Earth Are Canadians
Iron-rich chert from the Nuvvuagittuq Supracrustal Belt, Québec, Canada, containing tubular and ... More filamentous microfossils. A team of Canadian and French researchers has confirmed that Nunavik/Quebec in Northern Canada is home to the oldest known rocks on Earth, dating back over 4.16 billion years. The rocks of the Nuvvuagittuq Greenstone Belt, a rock formation preserved in a fold of the Canada shield, are believed to be over 4.3 billion years old, forming just 200 million years after Earth formed. They include the oldest known examples of sheeted dikes and pillow basalts. Such a succession of volcanic rocks is typically found in a spreading zone of a mid oceanic ridge, forming today Earth's oceanic crust. However, since first age estimates were published over 20 years ago, Various phases of tectonic deformation and chemical alteration makes it difficult to find pristine rock samples. There are also uncertainties involving the applied methods used at the time to date the rocks. In a new study, researchers sampled a new section of the greenstone belt, using modern dating methods they confirmed the high age of the entire formation. Samples were collected in 2017 near the municipality of Inukjuak, Nunavik, as part of Christian Sole's thesis, who completed a master's at the University of Ottawa in 2021. After preliminary analysis, additional work was carried out at the University of Ottawa and Carleton University, to confirm the age of the rocks. First age estimates were based on volcanic rocks — deposited as lava flows on the bottom of an ancient ocean — chemically altered as they came into contact with water. The researches focused on magmatic rocks, rocks crystallized before reaching the surface. Radioactive elements are trapped in the forming crystals, slowly decaying providing a natural timer for the rock's formation age. From left: Christian Sole, Professor Hanika Rizo and Professor Jonathan O'Neil collecting rock ... More samples. To establish the age of these rocks, the researchers combined petrology and geochemistry and applied two radiometric dating methods using different isotopes of the elements samarium and neodymium. The new dates 'gave exactly the same age,' says study author Jonathan O'Neil, University of Ottawa, in an interview to AP. The current study shows that dikes of magmatic rocks crossing these volcanic formations are 4.16 billion years old, which confirms that the volcanic rocks must be older, and thus, that this region of the Canadian north is indeed home to the oldest known rocks on Earth. 'Understanding these rocks is going back to the very origins of our planet. This allows us to better understand how the first continents were formed and to reconstruct the environment from which life could have emerged,' concludes O'Neil. The study,"Evidence for Hadean mafic intrusions in the Nuvvuagittuq Greenstone Belt, Canada," was published in the journal Science. Additional material and interviews provided by the University of Ottawa.
