Continental drift: supercontinent before Pangea (Introduction)

by David Turell , Wednesday, March 24, 2021, 18:27 (1341 days ago) @ David Turell

Possibly found:

https://phys.org/news/2021-03-clues-earth-supercontinent.html

"Curtin University research has uncovered the first solid clues about the very beginning of the supercontinent cycle of Earth, finding it was kick-started two billion years ago.

"Detailed in a paper published in Geology, a team of researchers from Curtin's Earth Dynamics Research Group found that plate tectonics operated differently before two billion years ago, and the 600 million years supercontinent cycle likely only started during the second half of Earth's life.

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"'Pangea was the first supercontinent scientists discovered early last century that existed some 300 million years ago and lasted until the age of the dinosaurs. Geologists realised more recently that at least two older supercontinents existed before Pangea in the past two billion years (Ga) in a 600 million year cycle. But what happened in the first 2.5 billion years of Earth's history is anybody's guess."

"'Our research was essentially testing two hypotheses—one is that the supercontinent cycle started prior to two billion years ago. Alternatively, the ancient continents (called cratons) only managed to get together in multiple clusters called supercratons, instead of forming a singular supercontinent."

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"'By precisely dating the rocks and measuring the samples' magnetic record, using a technique called palaeomagnetism, we are able to reconstruct where those rocks were (relative to the magnetic North pole) when they formed," Dr. Liu said.

"Co-author John Curtin Distinguished Professor Zheng-Xiang Li, from Curtin's School of Earth and Planetary Sciences, said by analysing their new data from Yilgarn, and comparing it with data available globally for other cratons, one thing became clear.

"'It was clear that we can almost rule out the existence of a long-lived single supercontinent before two billion years ago (2 Ga), although transient supercontinents may have existed" Professor Li said.

"'More likely, there could have been two long-lived clusters of cratons, or supercratons, before 2 Ga that were geographically isolated from each other, never forming a singular supercontinent.'"

Comment: The formation of continents allowed land organisms to develop. But obviously since life is about 3.8 bya life developed under water, unless there were cratons where life developed.