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Geology Bites

Alec Brenner on When Tectonic Plates First Moved

4/30/202629 min

A key development in the history of the early Earth is the formation of lithospheric plates that move independently of one another. In this episode, Brenner describes how he used paleomagnetic methods to detect relative motion between two ancient cratons, the East Pilbara and the Kaapvaal, 3.5 billion years ago. This is a full billion years earlier than any previous such detection, and it enables us to narrow down the kind of tectonics operating in the Paleoarchean. Of the candidate regimes, episodic subduction models fit his data best.

Brenner is a Postdoctoral Associate in the Department of Earth & Planetary Science at Yale University.

Clips

Earliest Plate Motions Detected
Not Necessarily Modern Subduction
Oldest Magnetic Reversal Found
Life, Heat, And Moving Plates
Averages Beat A Drunk Compass
Proving Ancient Signals Survive
Pilbara’s Timelessness And Art

Transcript preview

First 90 seconds

  1. Oliver Strimpel· Host0:00

    [ on-hold music] This is Geology Bites with Oliver Strunpe. Since almost all of our modern understanding of the Earth has something to do with the theory of plate tectonics, it is natural to ask when plate tectonics started. This is a very challenging question since so few rocks from the early Earth survived to the present day, and many of those that do have been heavily altered by intervening metamorphic or hydrothermal events. I discussed this topic in an earlier podcast episode with Peter Cawood. One key manifestation of plate tectonics is the relative motion of tectonic plates. My guest today recently succeeded in detecting such motion occurring fully a billion years earlier than any previous such detection. Alec Brenner studies Archean rocks using paleomagnetic and petrographic methods. He is a post-doctoral associate at Yale University. Alec Brenner, welcome to Geology Bites.

  2. Alec Brenner· Guest1:09

    Thanks for having me, Oliver.

  3. Oliver Strimpel· Host1:11

    Let's start with your results. Exactly what motions did you measure and when did they occur?

  4. Alec Brenner· Guest1:18

    We looked at a piece of Earth's crust that's been around for over three and a half billion years. Ancient pieces of crust like that are called cratons, and we specifically were looking at the Pilbara Craton. It's

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