Mar 17, 2017 06:27 AM EDT
The new research helps to find out the rocks from the eastern shore of the Hudson Bay in Canada. Those rocks contain some elements of Earth's earliest crust.
The rocks themselves are granites that are 2.7 billion old. But they still hold the chemical signals of the precursor rocks. These rocks were melted and recycled to from the rocks that exist today. As per a new study published by Science, these precursors formed around 4.3 billion years ago.
Now Earth is estimated to be about 4.6 billion old. Now researchers say, it is possible that parts of our planet's original crust still remain in place today. Scientist analyzed the isotope ratios of samarium and neodymium rocks from the Superior Province reported by Mail Online.
The new research is an attempt to peek the back into the Hadean on. This is a mysterious and rather molten phase of Earth's history. The Hadean begins with Earth's formation and ends about 4 billion years ago. O'Neil, a geoscientist at the University of Ottawa in Canada said they have a very limited amount of rock sample to understand the first billion years of Earth history.
Some scientists think that both the Jack Hills zircons and the Nuvvuaguittuq greenstone belt contain traces of the earliest life on the planet, though those findings are controversial. O'Neil and his co-author Richard Carlson were interested in 2.7 billion old granite. They knew that rocks of that sort had to be formed by a "parent" rock. Now the question was, how old was that parent rock?
To figure this out, the researchers turned to samarium-neodymium dating method. They found, one molecular variation or isotope of samarium and samarium-146 no longer exists on Earth. Samarium-146 decays into neodymium-142, so any rock that formed after the first 500 million years of Earth's history holds the same ratio. According to the researcher, any rock that shows variation in this neodymium-142 ratio must have formed in the first 500 million years of Earth history.
After detail analysis, the researchers estimate that the parent rock was 1.5 billion years older than the modern granites that survive today. The researchers also found that the parent rock was likely basaltic oceanic crust rather than dry land. The parent rock of the Hudson Bay granites stayed at the surface for more than a billion years before being recycled.