How a fracturing supercontinent forged rare volcanic rocks
With an unmolved eye, a rock on the side of the road is only that: a modest rock. For geologists, these are time capsules filled with data of some of the most turbulent days of our planet. Now scientists unravel a dramatic history secreted in rare volcanic rocks of around 800 million dollars called carbonatites. Discovered deep in central Australia, these apparently banal rocks start from geologists at a time when continents have torn violently.
The basic samples and the isotopic date of carbonatites rich in metals recently discovered on the northern territory of Australia indicate that the rocks have traveled near the surface of the earth between 830 and 820 million years. Meanwhile, the former supercontinent Rodinia separated. Rodinia incorporated almost all the masses of the earth for approximately 450 million years during the Eon Protrozoic (2.5 billion to 541 million years), more than a billion years before the last supercontinent, pangea, formed.
While the tectonic plates torn Rodinia about a billion years ago, the magma has risen from the mantle that changes the earth. Finally, this magma cooled, crystallized and solidified, creating these rare Australian carbonatites.
“This tectonic framework allowed the magma of carbonatitis to rise through flaw zones which had remained open and active for hundreds of millions of years, offering cast iron metals in the coat in the crust,” explained the university of study of Göttingen Geochemilian Dröllner in a press release. In other words, these rocks are probably directly from the deep median layer of the earth. Dröllner is also the co-author of a recent study published in the journal Geological magazine which describes the rocks.
The rocks of magma or lava, called ignful rocks, are common around the world. But carbonites like these are rare.
“Carbonatites are rare igneous rocks known to accommodate major global deposits of critical metals such as niobium and rare earth elements,” added the co-author and geologist Chris Kirkland. “But to determine when and how they formed were historically difficult due to their complex geological stories.”
To unlock their stories, the team used high resolution imaging to rebuild more than 500 million years of geological events that the rocks have experienced. With this approach, the team estimated that carbonatites formed 830 and 820 million years ago. Imaging and analysis of isotopes also helped the team to separate when the rocks have undergone more subtle changes compared to the most dramatic events, as when Rodina was tearing himself apart and the magma fled to the surface of the earth.
These carbonatites also contain one of the oldest deposits in the world of an important metal called Niobium. Nobium is a silver metal which is very resistant to heat and corrosion. As such, it is useful for producing high -resistant steel and energy technologies.
“These carbonatites are different from everything that is previously known in the region and contain significant concentrations of niobium, a strategic metal used to make steel lighter, a stronger steel for planes, pipelines and electric vehicles, and a key component in a new generation battery and suppactive technologies,” said Dröllner.
The team’s research puts new light on how these rare metals rich in metals can reach the surface of the earth. Even if this carbonatite deposit has billions of years, it could still play a role in protecting the future of our planet for hundreds of years to come.
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