Traces Of Earth’s 4.2 Billion-Year-Old Crust Found In Canada

First Posted: Mar 21, 2017 03:50 AM EDT

The chemical signatures of primordial Earth’s crust in rock samples have been unearthed recently in Quebec, Canada. The discovery of the ancient crust’s remnants has offered scientists an insight into the planet’s crustal past, something that has proven to be difficult for geologists.

The composition of Earth is unlike any other known planet or moon. Rocky crusts form and move over the Earth’s surface, which has forced older evidence of such crusts -- both continental and oceanic -- deep below the planet’s surface. “Finding remnants of this ancient crust has proven difficult, but a new approach offers the ability to detect the presence of truly ancient crust that has been reworked into ‘merely’ really old rocks,” Carnegie Institution for Science geologist Richard Carlson sad in a news release.

The team of researchers found an abundance of neodymium-142 in 2.7 billion years old granite rocks that were discovered from the Hudson Bay’s east shore. In fact, geologists found the ancient crust by locating neodymium-142, which is an elemental isotope created by the decay of samarium-146. It is a rare elemental isotope that ceased to exist when the planet was around 4 billion years old. The scientists analyzed the ratios of neodymium isotopes to identify the ancient rock remnants.

The findings of the research team, published in the journal Science, imply that the Canadian rocks are derived from ancient rocks that were formed-melted-recycled around 4.2 billion years ago. Incidentally, Earth’s early crust was formed shortly after its formation and survived for 1.5 billion years. Scientists say that the primordial crust was quite similar in appearance to the basaltic rock found in oceanic plates today.

The geologists, who recently discovered the chemical signatures, have suggested that their tool of examining neodymium-142 variation to understand the role of primordial crust to create younger, but still old, sections of the planet’s continental crust can help in investigating whether plate tectonics was not at work during the earliest part of Earth’s.

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