"This piece of crust has survived multiple mountain-building events between Australia, India and Antarctica," Droellner said. This period set the stage for the planet as it is today, but few hints of the earliest Earth have survived the constant upheaval of the planet's surface. Understanding the formation of crust 4 billion years ago can help researchers understand how the continents first formed, the researchers wrote. The boundary of the ancient crust is associated with gold and iron ore deposits, the researchers found, hinting at the importance of this very old crust in controlling the formation of rocks and minerals in the region. It is buried "tens of kilometers" below the surface, Droellner said. The old crust covers an area of at least 38,610 square miles (100,000 square kilometers), the researchers wrote in their paper, published online June 17 in the journal Terra Nova (opens in new tab). Earth's crust is way, way older than we thought Oldest evidence of tectonic plates sealed in ancient crystals This gravity data revealed a thick segment of crust in the southwestern part of Western Australia, likely to be the site of the buried ancient crust.
By measuring these variations in gravity, scientists can figure out how thick the crust is in different locations. Because Earth's crust varies in thickness, gravity varies slightly across the surface of the planet. To learn about where these minerals came from, the researchers turned to data collected by Earth-orbiting satellites. This dating revealed that the rocks holding these minerals formed between 3.8 billion and 4 billion years ago. Published January 1st 1972 by American West Independent Publishing. The relative amounts of each version, or isotope, tells researchers how long the elements have been decaying, providing a "clock" on the age of the zircons. Start by marking This Living Earth as Want to Read. The versions of these elements trapped in these zircons decay over billions of years. To do this, the researchers vaporized the zircons with powerful lasers, then analyzed the composition of two pairs of radioactive elements that the lasers had freed, uranium and lead and lutetium and hafnium. The sediments on this plain erode out of deeper rocks on the Australian continent. So Droellner and his colleagues decided to test the zircons in sediments from the Scott Coastal Plain, south of Perth. Geochemical hints in the sediments near this region suggested that there might be even older crust buried under newer rocks and sediments at the surface. The rocks around the Jack Hills, known as the Narryer Terrane, are no newbies, either: Some date back 3.7 billion years. These minerals have survived even as the rocks that once held them have eroded away. In Australia's Jack Hills, researchers have discovered tiny minerals called zircons dating back 4.4 billion years. Taxes, fees not included for deals content.The hidden piece of ancient crust is near where the oldest minerals on Earth have previously been found. If you have any questions or suggestions regarding this matter, you are welcome to contact our customer support team.īusinessYab is not a booking agent, and does not charge any service fees to users of our site.īusinessYab is not responsible for content on external web sites.
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