[Rockhounds] Study offers new, sharper proof of early plate tectonics, flipping of geomagnetic poles

[Kreigh Tomaszewski]

New research analyzing pieces of the most ancient rocks on the planet adds
some of the sharpest evidence yet that Earth's crust was pushing and
pulling in a manner similar to modern plate tectonics at least 3.25 billion
years ago. The study also provides the earliest proof of when the planet's
magnetic north and south poles swapped places.

The two results offer clues into how such geological changes may have
resulted in an environment more conducive to the development of life on the
planet.

The work, described in *PNAS* and led by Harvard geologists Alec Brenner
and Roger Fu, focused on a portion of the Pilbara Craton in western
Australia, one of the oldest and most stable pieces of the Earth's crust.
Using novel techniques and equipment, the researchers show that some of the
Earth's earliest surface was moving at a rate of 6.1 centimeters per year
and 0.55 degrees every million years.

That speed more than doubles the rate the ancient crust was shown to be
moving in a previous study
<https://phys.org/news/2020-04-tectonic-plates-shifting-earlier-previously.html>
by
the same researchers. Both the speed and direction of this latitudinal
drift leaves plate tectonics <https://phys.org/tags/plate+tectonics/> as
the most logical and strongest explanations for it.

"There's a lot of work that seems to suggest that early in Earth's history
plate tectonics wasn't actually the dominant way in which the planet's
internal heat gets released as it is today through the shifting of plates,"
said Brenner, a Ph.D. candidate in the Graduate School of Arts and Sciences
and member of Harvard's Paleomagnetics Lab. "This evidence lets us much
more confidently rule out explanations that don't involve plate tectonics."

https://phys.org/news/2022-10-sharper-proof-early-plate-tectonics.html