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Scientists have found evidence in ancient rocks in southern Greenland that indicate much of the Earth was once fully melted.
Very little is known about what Earth looked like during the Hadean Aeon, which is characterized by the initial formation of the planet, the stabilization of its core and crust, and the formation of its early atmosphere.
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In a study published Friday in the journal Science Advances, geochemists working together from around the world reported that their analysis of billions of years old rocks of the Isua supracrustal belt – which contains the oldest known rocks on the planet – was found. chemical traces of an ocean of magma.
Their 3.7 billion-year-old basalt rock samples contained high levels of heavy iron isotopes, as measured by chromatography and mass spectroscopy.
Researchers have identified isotopes of hafnium and neodymium, as well as rare tungsten isotopes from an “old parent isotope” that only existed in Earth’s first 45 million years, according to LiveScience.
“It was a combination of some new chemical analyzes we did and previously published data that told us that the rocks of Isua may contain traces of ancient material. The isotopes of hafnium and neodymium were really enticing, because these isotopic systems are very difficult to modify – so we had to look at their chemistry in more detail, ”explained the study co-author and associate professor at the University. Carleton, Dr. Hanika Rizo.
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Isotopes of iron confirmed to the team that Isua’s rocks consist of parts of the Earth’s interior that formed 4.5 billion years ago as a result of the crystallization of oceanic magma. .
They reported that the crystal residue had melted and mixed with other molten rock as it moved into the Earth’s upper mantle, carrying the isotopes with rock from the lower and upper mantle.
It is less clear how they appeared on the surface, but a Cambridge University statement notes that catastrophic collisions during the formation of the Earth and the Moon would have generated enough energy to melt the interior of the planet – which would eventually cool and crystallize – with the isotopes. migrating by crystallization and reflow.
Since then, tectonic changes have “recycled” almost all rocks over four billion years old.
“It is extremely difficult to find the geological evidence of the former molten state of the Earth. Indeed, events of crystallization of the oceans of magma would have occurred more than 4 billion years ago, and much of them. Geological records of this period in Earth’s history have since been lost, “Senior author Helen Williams, professor of geochemistry at Cambridge, told Fox News Saturday.
Additionally, since much of the deep Earth is inaccessible, Williams and the team had to rely on nature to help their research, although she noted that the chemistry of the volcanic rocks was vital to their findings.
“Our results provide tantalizing evidence for the presence of deep magmatic ocean crystals formed at a time when the Earth was almost completely melted,” she said.
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“While the results of our research are very exciting, they also raise other questions. What are the processes responsible for the fusion events that produced the Isua volcanic rocks? Did all the ancient volcanic rocks originate from regions of the Earth’s mantle containing residual crystals formed during the cooling of an ocean of magma? Are any of these materials still present inside modern Earth and if so, can they explain the unique chemistry of magmas that erupted in “hot spots” like Hawaii and Iceland? “
“Obviously, there is still a lot to discover,” she said.
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