The new research shows that the Earth's crust was pushing and pulling in a way similar to plate tectonics at least 3.25 billion years ago. The proof of when the north and south poles swapped places was found in the study.
Two results offer clues into how geological changes may have resulted in an environment that is more favorable to the development of life on the planet.
One of the oldest and most stable pieces of the Earth's crust was the focus of the work. Some of the Earth's earliest surface moved at a rate of 6.1 centimeters per year and 0.55 degrees per million years.
The ancient crust was shown in a previous study to be moving at a faster rate than the current one. Plate tectonics is the most logical and strongest explanation for the latitudinal drift.
There is a lot of work that suggests plate tectonics wasn't the dominant way in which the planet's internal heat is released. We can more confidently rule out explanations that don't involve plate tectonics.
There are two phenomena that can cause the Earth's surface to shift but aren't part of modern-style plate tectonics. The higher rate of speed is not consistent with the other two processes.
What's believed to be the oldest evidence of the reversal of the Earth's magnetic field is described in the paper. In the last 83 million years, the pole has reversed many times, and in the last 160 million years, it has reversed many times, according to NASA.
The reversal tells us a lot about the magnetic field on the planet. The magnetic field was strong enough to keep solar winds out of the atmosphere. There are clues to the conditions under which the earliest forms of life developed.
The picture of an early earth is painted by it. It had a lot of the same sorts of dynamic processes that result in an Earth that has a stable environment.
The outer shell of the planet is made up of 15 shifting blocks of plate. Over the course of billions of years, the plates drift into each other, forming new continents and mountains, exposing new rocks to the atmosphere, and leading to chemical reactions that kept the surface temperature stable.
It's difficult to find evidence of when plate tectonics started because the oldest pieces of crust are never to be seen again. Only 5 percent of the rocks on Earth are more than 2.5 billion years old.
The study shows that early forms of life came about in a more moderate environment and that the movement of tectonics occurred relatively early in Earth's 4.5 billion-year history. There were members of the project who went to the Pilbara in the year 2000. They drilled into the primordial and thick slab of crust to get samples that were analyzed for their magnetic history.
The researchers created a suite of new techniques for determining the age and way the samples became magnetized by using magnetometers, demagnetizing equipment, and the quantum diamond microscope. Researchers can determine how, when, and which direction the crust shifted by using this information.
The Departments of Earth and Planetary Sciences and of Physics collaborated on the development of the quantum diamond microscope.
Fu and Brenner plan to study other ancient crusts around the world in the future. When the Earth's magnetic poles flip, they want to find evidence of plate motion.
Fu said that being able to reliably read these ancient rocks opens up many possibilities for observing a time period that often is known more through theory than solid data. We have a good chance of reconstructing how the Earth interior processes that drive plates have changed over time.
More information: Brenner, Alec R., Plate motion and a dipolar geomagnetic field at 3.25 Ga, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2210258119. doi.org/10.1073/pnas.2210258119 Journal information: Proceedings of the National Academy of Sciences
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