Earth got unusually quiet and shut down geological activity 2 billion years ago but no one knows why

Around 2.3 to 2.2 billion years ago, the Earth experienced a geological lull, almost like a mid-life crisis, which saw an almost complete shutdown of continental magmatism. The lull in rock-forming activities took place during the Palaeoproterozoic geologic era.

The Palaeoproterozoic geologic era was a much simpler time for our planet. This is when the Earth's atmosphere began getting the very first hint of oxygen and our planet's very first supercontinent Nuna was in the process of beginning to be formed. However, it is still unclear as to what caused the Earth's geological lull and what impact the phase may have had over our planet's geological evolution.

According to a new study that backs the theory that the Earth experienced a geological slowdown, the Earth's so-called mid-life crisis "profoundly shaped" our planet's geological record to date. According to the new research, the number of volcano eruptions, tectonic plate movements and more slowed down during this period.

"Our research shows a bona fide gap in the Palaeoproterozoioc geologic record, with not only a slowing down of the number of volcanoes erupting during this time, but also a slow-down in sedimentation and a noticeable lull in tectonic plate movement," the lead researcher of the study, Dr. Christopher Spencer from the School of Earth and Planetary Sciences at Curtin University, said in a statement.

"The early Paleoproterozoic was a significant time in Earth history. It was at this time when the atmosphere got its first whiff of oxygen and also the first global glaciation event," Dr. Spencer added. "But this was also a period where other geologic processes effectively shut down. It's almost as if the Earth experienced a mid-life crisis."

The research gathered massive amounts of geological data and involved the analysis of rocks from Western Australia's Stirling Ranges, China, Northern Canada and Southern Africa.

"The more rocks and data we collected the clearer it is that there is very little preserved record for this period," Dr. Spencer said.

According to the study's lead scientist, the Earth's mantle was once much hotter than it is at present. However, the mantle cooled over time, thanks to volcanoes, which eventually led to a slowing down of geological processes. The new study indicates that this steady slowdown led to "dramatic geological changes".

"This 'dormant' period lasted around 100 million years and signalled what we believe was a shift from 'ancient-style' tectonics to 'modern-style' tectonics more akin to those operating in the present day," Dr. Spencer said. "Following this dormant period Earth's geology started to 'wake-up' again around 2.2 to 2.0 billion years ago with a 'flare-up' of volcanic activity and a shift in the composition of the continental crust."

This unusually dormant phase in the Earth's history likely indicates a significant impact in our planet's tectonic movements. The new research could likely refuel the debate over how the Earth's continents formed.

The new research has been published in the journal Nature Geoscience.