In a new study, scientists at the Australian National University (ANU) investigated the formation of the giant mountain throughout earth history. They used a combination of mineral and rare earth elements found in the roots of high mountains.
Their analysis suggests that these supermountains, at least as high as the Himalayas and stretching up to 8,000 kilometers across entire supercontinents, played a crucial role in the evolution of early life on Earth.
Lead author, ANU Ph.D. candidate Ziyi Zhu, said there are links between these two instances of supermountains and the two most important periods of evolution in Earth’s history.
“There’s nothing like these two supermountains today. It’s not just their height – if you can imagine the 2,400 km long Himalayas repeated three or four times, you get an idea of the scale,” she said.
“We call the first example the Nuna Supermountain and the second as Transgondwanan Supermountain.”
To identify periods of extensive high mountain (supermountain) formation, scientists used traces of zircon with low lutetium content found in the roots of high mountains where they form under intense pressure.
The data reveal that the first giant mountain formed between 2,000 and 1,800 million years ago and the second between 650 and 500 million years ago. Both mountain ranges rose during periods of supercontinent formation.
Zhu said, “The first supermountain coincides with the likely appearance of eukaryotes, organisms that later gave rise to plants and animals. The second coincides with the appearance of the first large animals 575 million years ago and the Cambrian explosion 45 million years later when most animal groups appeared in the fossil record.”
Co-author Professor Jochen Brocks said: “What’s stunning is the entire record of mountain building through time is so clear. It shows these two huge spikes: one is linked to the emergence of animals and the other to the emergence of complex big cells.”
The erosion of mountains provided vital nutrients like phosphorous and iron to the oceans, supercharging biological cycles and driving the evolution to greater complexity. It may have also increased oxygen levels in the atmosphere, needed for complex life to breathe.
Ms. Zhu said, “The early Earth’s atmosphere contained almost no oxygen. Atmospheric oxygen levels are thought to have increased in a series of steps, two of which coincide with the supermountains.”
“The increase in atmospheric oxygen associated with the erosion of the Transgondwanan Supermountain is the largest in Earth’s history and was an essential prerequisite for the appearance of animals.”
Co-author Professor Ian Campbell said, “The time interval between 1,800 and 800 million years ago is known as the Boring Billion because there was little or no advance in evolution.”
“The slowing of evolution is attributed to the absence of supermountains during that period, reducing the supply of nutrients to the oceans.”
“This study gives us markers, so we can better understand the evolution of early, complex life.”
- Ziyi Zhu et al. The temporal distribution of Earth’s supermountains and their potential link to the rise of atmospheric oxygen and biological evolution. DOI: 10.1016/j.epsl.2022.117391