Like today’s high mountains, supermounts arose when the tectonic plates of the Earth’s crust collide with each other. But even today’s great mountain ranges pale in comparison to the two great mountains the earth has ever known. The first time this happened was between 2 and 1.8 billion years ago, said Zhi Zhou, a geologist at the Australian National University. This mountain is known as Nouna Super Mountain† Supermounts II, and Transgondwana Super MountainIt arose between 650 and 500 million years ago. Both supermounts were at least three to four times larger than the Himalayas.
Chu and her team studied the formation of supermountains using zircon, a mineral that is particularly resistant to weathering and forms, among other things, when mountain ranges form. Zircon is popular with geologists because the mineral contains radioactive isotopes that allow the exact age of the rock to be dated.
However, the dating of these two super-mountains surprisingly and accurately coincided with two pivotal moments in the evolution of life on Earth, says Chu. The super mount Nuna overlaps with the emergence of eukaryotes, the first organisms to have a nucleus in every cell, and the basic building blocks for the later evolution of plants and animals. The second super mountain, the giant Transgondwana, coincides with the Cambrian explosion, a period when a large number of new species appeared, including the first large animals.
Zhou said that the coincidence of two key moments in Earth’s geological and biological history does not mean that there is a causal relationship. We argue that there is, however, such an association. The formation and erosion of super-mountains brought a huge amount of nutrients into the oceans, more than in other periods. The higher the height of the mountains, the faster the erosion and the greater the volume of sediment.
The sediments brought essential nutrients into the life cycle, such as iron and phosphorous. This surplus of nutrients caused an explosion of new primitive organisms such as algae and cyanobacteria. For example, the bottom of the food pyramid has expanded significantly, benefiting other, more complex life forms. In addition, the expanding web of life increases the chance of mutations and evolution.
Indirectly, giant mountains also had an impact on the evolution of the atmosphere. Because the additional influx of nutrients into the oceans and the resulting explosion of organisms led to an increase in photosynthesis, the process that turns carbon dioxide into oxygen. As a result, Zhou explained, the oxygen content in the atmosphere increased dramatically.
Chu says that the hypothesis that giant mountains played an important role in the evolution of life on Earth arose by chance. “Our geological data has remarkably coincided with the evolution of life and helps to better understand this complex story.”
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