According to new research from the Australian National University and the Queensland University of Technology, the supermountains formed twice in Earth’s history: the first between 2 and 1.8 billion years ago and the second between 650 and 500 million years ago; both mountain ranges rose during periods of supercontinent formation; their erosion may be connected to the emergence of the first macroscopic organisms, the radiation of early eukaryotes, the proliferation of chlorophyte algae, and the emergence of large, animal-like organisms.
Zhu et al. suggest rapid supermountain erosion increased atmospheric oxygen and nutrient levels. Image credit: Keith Johnston
Australian National University Ph.D. candidate Ziyi Zhu and colleagues tracked the formation of the ancient supermountains throughout Earth’s history using traces of zircon with low lutetium content — a combination of mineral and rare earth element only found in the roots of high mountains where they form under intense pressure.
They found that the first supermountains formed between 2 and 1.8 billion years ago, during the assembly of the supercontinent Nuna, and the second 650-500 million years ago, during the amalgamation of the supercontinent Gondwana.
“There are links between these two instances of supermountains and the two most important periods of evolution in Earth’s history,” Zhu said.
“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.”
“We call the first example the Nuna Supermountain. It coincides with the likely appearance of eukaryotes, organisms that later gave rise to plants and animals.”
“The second, known as the Transgondwanan Supermountain, 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.”
“What’s stunning is the entire record of mountain building through time is so clear,” said Professor Jochen Brocks, a researcher at the Australian National University.
“It shows these two huge spikes: one is linked to the emergence of animals and the other to the emergence of complex big cells.”
When the mountains eroded they provided essential nutrients like phosphorous and iron to the oceans, supercharging biological cycles and driving evolution to greater complexity.
The supermountains may also have boosted oxygen levels in the atmosphere, needed for complex life to breathe.
“The early Earth’s atmosphere contained almost no oxygen,” Zhu said.
“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.”
There is no evidence of other supermountains forming at any stage between these two events, making them even more significant.
“The time interval between 1.8 billion and 800 million years ago is known as the Boring Billion, because there was little or no advance in evolution,” said Professor Ian Campbell, a researcher at the Australian National University.
“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.”
The research is described in a paper in the journal Earth and Planetary Science Letters.
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Ziyi Zhu et al. 2022. The temporal distribution of Earth’s supermountains and their potential link to the rise of atmospheric oxygen and biological evolution. Earth and Planetary Science Letters 580: 117391; doi: 10.1016/j.epsl.2022.117391
