Australia's Conversation website published on December 3 titled "How Did Plankton Help Form The Earth's Mountain Ranges 2 Billion Years Ago?" article by John Parnell, Professor of Geology and Petroleum Geology at the University of Aberdeen, UK. The full text is excerpted below:
A world without large mountains such as the Himalayas, the Alps, and the Andes is unthinkable, but they are not part of the Earth's landscape from the beginning. Mountains didn't begin to form widely until 2 billion years ago, when halfway through Earth's history. Now, our research reveals how primitive life played a key role in shaping Earth.
While the formation of mountain ranges is often associated with the massive slabs of rock being pushed upwards due to the collision of tectonic plates in the crust, our research suggests that this process was triggered by the abundant nutrients in the ocean that caused the "plankton explosion" 2 billion years ago.
Before mountain ranges formed, plate movements that altered the distribution of oceans and continents occurred only on a limited scale, but these plate movements were essential for the formation of mountains. The pressure generated by one plate pushing another — usually one oceanic plate hitting a continental plate — causes ocean rock slabs to break and stack on top of each other as they are pushed from behind.
Over the course of millions of years, stacked rocks have continued to increase, forming mountains. Just as the Himalayas were formed by oceanic rocks between India and Eurasia, these rocks are pushed north until the ocean disappears, while the rocks it leaves behind are stacked into mountains.
Through fossil marine life found on the Tibetan Plateau at an altitude of thousands of meters, we know that these mountains originally came from the ocean. But stacking huge rock slabs on such a large scale requires a lot of lubrication, otherwise the friction will cause them to stop moving. The lubricant in this is carbon, which becomes part of ocean rock when dead plankton fall to the bottom of the ocean and are buried.
Plankton have lived in our oceans for more than 3 billion years, but by 2 billion years ago, their numbers exploded as enough nutrients entered the water. Life at the time was still only in the form of single cells, but the cells became much larger and contained more carbon than before.
They sink quickly after death and are buried in the dirt, forming rocks with an unprecedented carbon content and turning into graphite under the action of high temperature and pressure, and graphite is a good lubricant.
The large amount of graphite accumulated on the seafloor has a profound effect, lubricating the formation of mountains. While we have long known that lubricants are indispensable to the tectonic process of the Earth's crust, our research shows that it is the large amounts of carbon in the ocean that play a crucial role in the thickening of the crust that forms mountains.
This process has continued ever since. Salt and other geological layers also play a role, but the graphite layers of 2 billion years ago are particularly lubricated, and some have been involved in the formation of mountains more than once.
Our study analyzed 20 mountain ranges that have formed around the world since then. From Australia to China, from South America to the Arctic to northwestern Scotland, where we can see sliding surfaces of graphite-bearing rocks that formed during the earthquakes that occurred during the earliest shaping of the mountains.
Without carbon from countless plankton cells, the distribution of tectonic plates in the Earth's crust might have become very different, and we might not have the mountains we know. Our planet is fundamentally shaped by life.
Source: Reference News Network