14 DAY TRIAL // A new study by investigators at the Massachusetts Institute of Technology (MIT) manages to reveal the intricate and ancient history of the North American craton, a section of our planet's crust that has been around for a very long time, and that lies right in the middle of the continent.
Earth's rocky layer, the lithosphere, is in a constant process of renewal, as evidenced by plate tectonics. Huge pieces of crust are constantly colliding with each other, submerging in the mantle or raising tall mountains and causing earthquakes or volcanic eruptions.
Entire continents and oceans lie atop such massive plates. What is interesting to note about some of them is that certain sections have never been recycled through the mantle for billions of years. These extremely ancient sections are called cratons.
The core of the North American continent contains such a craton, right beneath Wyoming Province. This section of the crust contains the oldest rocks on the continent, and some of the oldest in the world.
Analyzing it could reveal some of our planet's deepest secrets, scientists say, which is why the MIT team decided to investigate its composition in detail. Details of their work appear in the January 6 issue of the top journal Science.
The group developed a method for detecting when continents transition from high to low rates of erosion. This helped them determine that the continental crust at the North American craton experienced a brief, intense period of erosion between 1.8 and 1.5 billion years ago.
After that, it became much more stable, and that state continued all the way to the present. “In our continental masses, the most stable regions have been exactly this way for billions of years,” MIT Department of Earth, Atmospheric and Planetary Sciences expert Terrence Blackburn explains.
The graduate student was the lead author of the new study. “Today the North American craton is eroding very slowly, and our data tell us regions like that have been behaving like that for vast amounts of Earth’s history,” he adds.
The main application this research has is in developing models for reconstructing the evolution of other continental masses and cratons. This could prove to be very important for determining some of our planet's rich tectonic history.