Supervolcanoes like Yellowstone may have been more active in the past

National Science Foundation ^ | 6/2/2016 | Carol Frost, Davin Bagdonas

[JimSEA]

Magma located under areas that include the Yellowstone region and the western margin of North and South America can erupt violently, spewing vast quantities of ash into the air, followed by slower flows of glassy, viscous magma.

[A] new study by University of Wyoming researchers suggests scientists can go back to the past to study present-day solidified magma chambers where the erosion has removed overlying rock, exposing granite underpinnings.

One such large granite body, the 2.62 billion-year-old Wyoming batholith, extends more than 125 miles across central Wyoming.

University of Wyoming earth scientist Davin Bagdonas traversed the Granite, Shirley and Laramie Mountains to examine the batholith. He found remarkable uniformity, with similar minerals throughout.

Says Bagdonas, who worked on the project with Frost, "only minor variations were observed in granite near the roof and margins."

That homogeneity, or sameness, indicates the crystallizing magma was well-mixed. However, more subtle variations across the batholith show that the magma formed by the melting of multiple rock sources that rose through several conduits.

Large bodies composed of biotite granite, such as the Wyoming batholith, are more common in the Neoarchean era (2.8 billion-2.5 billion years ago) than in younger terrains. The reason may relate to higher radioactive heat production in the past, which provided power to drive extensive granite formation.

"If these ancient rocks are analogs for the magma systems underlying modern supervolcanoes, then explosive volcanism may have been far more abundant in Earth's past than it is today," the researchers conclude in their paper.

[Caipirabob]

Fascinating!!!

[LaRueLaDue]

Yeah, it would be very cool go and see all that first hand... Very cool indeed!

If I am remembering right, I think that they believe that those kimberlites are from the middle to lower mantle, not the core area. And they wouldn’t be from before the core was formed, as it was formed 30-50 million years after the formation of the solar system/earth, predating the oldest rocks and these rocks in particular by many millions to billions of years. The ages of emplacement of the south african kimberlites is approximately 120 million years BP and the australian ones 1.2 billion years BP.

[Fightin Whitey]