Twice in the history of our planet, colossal mountain ranges that rose as high as the Himalayas and stretched for thousands of kilometers, divided the ancient supercontinent in two. These mountain ranges are called “overpasses” by geologists, according to Live Science.
“There is no such thing as two mountains today,” said Ziyi Zhu, a postdoctoral fellow at the Australian National University in Canberra and lead author of a new study on these majestic mountains.
“It's not just their height. To get an idea of the scale, imagine the Himalayas, which are 2,400 kilometers long, repeated three or four times.
These prehistoric peaks were more than just an incredible spectacle, according to new research by Zhu and her colleagues published in the journal Earth and Planetary Science Letters. The formation and destruction of these two giant mountain ranges may also have fueled two of the largest eruptions of life in the history of our planet – the first appearance of complex cells about 2 billion years ago and the eruption of Cambrian marine life before from 541 million years.
It is possible that as these vast mountain ranges eroded, they fed the oceans enormous amounts of nutrients, accelerating energy production and evolution, the researchers wrote.
The rise of the giants
Mountains are formed when the Earth's ever-moving tectonic plates crush two land masses together, pushing surface rocks to enormous heights. Mountains can grow for hundreds of millions of years or more, but even the highest mountain ranges are born with an expiration date, as erosion by wind, water and other natural forces immediately begins to reduce these peaks.
Scientists can compose the history of Earth's mountains by studying the minerals left behind by these peaks in the planet's crust. Zirconium crystals, for example, form under high pressure deep beneath heavy mountain ranges and can survive on rocks for a long time after the disappearance of mountains. The exact elemental composition of each zirconium grain can reveal the conditions in the crust when and where these crystals formed.
In their new study, researchers looked at zirconia with low levels of bathtub, a rare terrestrial element that forms only at the base of high mountains. The data revealed that there were two periods in the history of the Earth during which supernovae formed – one lasting from about 2 billion to 1.8 billion years ago and the second from 650 million to 500 million years ago.
Previous studies have suggested the existence of this second epic mountain range, known as the Transgondwanan Mountains, because it crossed the vast Godwana (a single giant continent containing the arid masses of present-day Africa, South America, South America, South America, South America, of the Arabian Peninsula). However, Mount Nuna had not been located until now.
The distribution of zirconium crystals showed that both of these ancient mountains were enormous – probably extending more than 8,000 miles, or about twice the distance from Florida to California.
Explosion of life
As the two mountains eroded, they fed the oceans enormous amounts of nutrients such as iron and phosphorus, the researchers wrote in their article. These nutrients could have significantly accelerated biological cycles in the ocean. In addition to leaking nutrients, eroded mountains may also have released oxygen into the atmosphere, making the Earth even more hospitable to complex life.
The formation of the supernova Nuna, for example, coincides with the appearance of the first eukaryotic cells on Earth – cells that contain a nucleus and that eventually evolved into plants, animals and fungi. Meanwhile, the Transgondwanan mountain pass probably eroded just as another eruption was unfolding on Earth's seas.
“Mount Transgondwanan coincides with the appearance of the first large animals 575 million years ago and the Cambrian eruption 45 million years later, when most groups of animals appeared in the fossil record,” Zhu said.
In their research, the team also confirmed previous studies that found that mountain formation stopped on Earth about 1.7 billion to 750 million years ago. Geologists refer to this period as the “boring billion” because life on Earth's seas has apparently stopped evolving (or at least evolved painfully slowly), according to Live Science. Some scientists speculate that the lack of new mountain formation may have prevented the release of new nutrients into the oceans during this period, effectively starving sea creatures and halting their evolution.
Although more research is needed to confirm the link between the supernovae and the eruption of life on Earth, this study seems to support the theory that the most productive biological eruptions on our planet occurred in the “shadow” of some truly colossal mountains.
Source: in.gr
