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Plate tectonics may have been active on Earth since the very beginning

Date:
September 26, 2018
Source:
University of Tennessee at Knoxville
Summary:
A new study suggests that plate tectonics -- a scientific theory that divides the earth into large chunks of crust that move slowly over hot viscous mantle rock -- could have been active from the planet's very beginning. The new findings defy previous beliefs that tectonic plates were developed over the course of billions of years.
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A new study suggests that plate tectonics -- a scientific theory that divides Earth into large chunks of crust that move slowly over hot viscous mantle rock -- could have been active from the planet's very beginning. The new findings defy previous beliefs that tectonic plates were developed over the course of billions of years.

The paper, published in Earth and Planetary Science Letters, has important implications in the fields of geochemistry and geophysics. For example, a better understanding of plate tectonics could help predict whether planets beyond our solar system could be hospitable to life.

"Plate tectonics set up the conditions for life," said Nick Dygert, assistant professor of petrology and geochemistry in UT's Department of Earth and Planetary Sciences and coauthor of the study. "The more we know about ancient plate tectonics, the better we can understand how Earth got to be the way it is now."

For the research, Dygert and his team looked into the distribution of two very specific noble gas isotopes: Helium-3 and Neon-22. Noble gases are those that don't react to any other chemical element.

Previous models have explained Earth's current Helium-3/Neon-22 ratio by arguing that a series of large-scale impacts (like the one that produced our moon) resulted in massive magma oceans, which degassed and incrementally increased the ratio each time.

However, Dygert believes the scenario is unlikely.

"While there is no conclusive evidence that this didn't happen," he said, "it could have only raised the Earth's Helium-3/Neon-22 ratio under very specific conditions."

Instead, Dygert and his team believe the Helium-3/Neon-22 ratio raised in a different way.

As Earth's crust is continuously formed, the ratio of helium to neon in the mantle beneath the crust increases. By calculating this ratio in the mantle beneath the crust, and considering how this process would affect the bulk Earth over long periods of time, a rough timeline of Earth's tectonic plate cycling can be established.

"Helium-3 and Neon-22 were produced during the formation of the solar system and not by other means," Dygert said. "As such, they provide valuable insight into Earth's earliest conditions and subsequent geologic activity."


Story Source:

Materials provided by University of Tennessee at Knoxville. Note: Content may be edited for style and length.


Journal Reference:

  1. Nick Dygert, Colin R.M. Jackson, Marc A. Hesse, Marissa M. Tremblay, David L. Shuster, Jesse T. Gu. Plate tectonic cycling modulates Earth's 3He/22Ne ratio. Earth and Planetary Science Letters, 2018; 498: 309 DOI: 10.1016/j.epsl.2018.06.044

Cite This Page:

University of Tennessee at Knoxville. "Plate tectonics may have been active on Earth since the very beginning." ScienceDaily. ScienceDaily, 26 September 2018. <www.sciencedaily.com/releases/2018/09/180926192044.htm>.
University of Tennessee at Knoxville. (2018, September 26). Plate tectonics may have been active on Earth since the very beginning. ScienceDaily. Retrieved April 18, 2024 from www.sciencedaily.com/releases/2018/09/180926192044.htm
University of Tennessee at Knoxville. "Plate tectonics may have been active on Earth since the very beginning." ScienceDaily. www.sciencedaily.com/releases/2018/09/180926192044.htm (accessed April 18, 2024).

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