The new research from Harvard geologists Alec Brenner and Roger Fu reports that Earth's crust has been pushing and tugging about 3.2 billion years ago, much like modern plate tectonics. Their study also offers the earliest evidence of when the planet's magnetic north and south poles switched places.
The findings of the study, titled "Plate motion and a dipolar geomagnetic field at 3.25 Ga," published in the journal PNAS, may offer clues as to how such geological changes may have resulted in an environment that allows life to exist on Earth.
In between North American and Eurasian tectonic plates, Iceland's Silfra fissure is one of the world's most famous dive sites, popular with tourists who venture into its icy waters.
Finding Evidence of Early Plate Tectonics
The team of geologists explored a portion of one of the oldest and most stable parts of Earth's crust by focusing on a region of Pilbara Craton in Western Australia, The Harvard Gazette reports.
They used innovative methods that combined magnetometers, demagnetizing tools, and the Quantum Diamond Microscope to figure out when, how, and in which direction the crust shifted to identify the magnetic influence from the geomagnetic poles. They found that some of the oldest crust was shifting at 6.1cm per year and 0.55 degrees every several million years.
The team argues that the speed and direction of ancient crust movement are the earliest evidence of plate tectonics. Previous studies found that the ancient crust was moving slower than their current study's findings.
Brenner, a member of Harvard's Paleomagnetics Lab, said in the press release that a lot of work seems to suggest that plate tectonics in Earth's history was not the dominant way in which the internal heat of the planet is released, unlike today. But their evidence says otherwise and helps researchers rule out explanations that do not involve plate tectonics.
They can now argue against the "true polar wander" and "stagnant lid tectonics" that explain the cause of the shift on Earth's crust that is not part of modern plate tectonics. The new study's results lean more toward plate tectonic motion because the newly discovered higher rate of speed does not coincide with aspects explained by the two processes.
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New Study Supports Theory That Earth's Geomagnetic Fields Were Reversed
Aside from plate tectonics, researchers also discussed the possible earliest proof that Earth's geomagnetic fields were reversed, which caused the flipping of positions of the North and South poles.
According to NASA, this type of flipping magnetic field is typical throughout the planet's geological history. In fact, the geomagnetic pole has reversed 183 times in the past 83 million years and perhaps several hundred times more in the last 160 million years.
The reversal of the North and South poles revealed much of Earth's magnetic field about 3.2 billion years ago. Per Interesting Engineering's report, the magnetic field was probably steady and powerful enough to prevent solar winds from destroying the atmosphere and create an environment that could support life.
Through this understanding of the flipping magnetic field and findings on plate tectonics, researchers believe it provides hints on the conditions in which the earliest life forms originated.
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