Scientists believe they have found a window into the beginnings of time on Earth beneath the depths of the Pacific Ocean.
A team led by geophysicist Simon Lamb of the University of Wellington and scientist Cornel de Ronde of GNS Science said the key to our past lies in a remote corner of South Africa and deep on the seabed off the coast of New Zealand.
What do these two places on opposite sides of the world have in common?
Together, they shed light on the world in its early days and offer unexpected clues about the origins of the planet we know today – and possibly the origins of life itself.
Writing for The conversationThe scientists explained that they began their work after de Ronde created a new, detailed geological map of an area called the Barberton Greenstone Belt, located in South Africa’s Highveld region.
“Despite many attempts, it has been difficult to decipher the geological formations of this region,” they write.
They claim that the belt’s bedrock is inconsistent with our then generally accepted understanding of plate tectonics.
However, they claim that their new research has provided “the key to cracking this code.”
A section of the South African Barberton Greenstone Belt(International Commission for Geoheritage)
De Ronde’s map revealed a fragment of the ancient deep sea floor in the Barberton Greenstone Belt, which formed about 3.3 billion years ago, when the world was just 1.2 billion years old.
“However, there was something very strange about this seabed,” write Lamb and de Ronde.
“And to understand the whole thing, we needed to study rocks that were deposited in New Zealand, at the other end of Earth’s long history.”
The two experts argue that the common idea of the early Earth as a fiery ball of molten magma whose surface was too weak to form rigid plates – and thus to suffer earthquakes – is wrong.
Rather, they assume that the young planet was continuously shaken by large earthquakes that were triggered each time one tectonic plate slipped beneath another in a subduction zone.
Looking at de Ronde’s map of the Barberton Greenstone Belt, they realized that the “jumbled” rock layers were reminiscent of recent submarine landslides that had occurred in New Zealand.
These landslides were triggered by severe earthquakes along the country’s largest fault, the so-called megathrust in the Hikurangi subduction zone, where the bedrock consists of a mishmash of sedimentary rocks.
The Hikurangi Subduction Zone Projectyoutube.com
These rocks were originally deposited on the seafloor off the coast of New Zealand about 20 million years ago, on the edges of a deep ocean trench where large earthquakes frequently occurred.
By studying the formation of this New Zealand rock layer, experts claim to have solved the mystery behind the formations of the Barberton Greenstone Belt.
These structures, like their more recent successors, were “the remnants of a massive landslide that contained sediments deposited both on land and in very shallow water, mixed with those accumulated on the deep sea floor,” they concluded.
To put it simply: If the rock layers of New Zealand were formed by earthquakes, then the same applies to the rock layers in the Barberton Greenstone Belt. This refutes the theory that the early Earth was not equipped to withstand such earthquakes.
In addition, Lamb and de Ronde believe that their work “may have revealed other mysteries as well,” because, as they point out, “subduction zones are also associated with explosive volcanic eruptions.”
As an example, they cite the Hunga Tonga-Hunga Ha’apai volcano in Tonga, which erupted in January 2022 with the energy of a “60-megaton atomic bomb,” hurling a massive cloud of ash into space, through which more than 200,000 lightning strikes flashed over the next eleven hours.
“In the same volcanic region, underwater volcanoes eject an extremely rare type of lava called boninite. This is the closest modern example of a lava that was widespread on early Earth,” they add.
Clouds of ash pierced by lightning were spewed out by the violent volcanic eruption in 2022(Tonga Geological Services via NOAA)
Lamb and de Ronde argue that the large amounts of volcanic ash found in the Barberton Greenstone Belt “may be ancient evidence of similar volcanic violence.”
And, even more interestingly, they suggest that the associated lightning strikes may have “created the crucible of life in which the basic organic molecules were forged.”
In other words, subduction zones are not only the source of tectonic chaos, they may also have been the spark that ignited the flame of life itself.
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