Posted on 06/04/2016 11:13:08 AM PDT by 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.
"One such large granite body, the 2.62 billion-year-old Wyoming batholith, extends more than 125 miles across central Wyoming." A magma chamber that size, the extent of which and composition of which is preserved in this batholith, is one of many monstrous granite formations that give evidence to the violence of earth's past.
One hopes.
Uh, thermodynamics says the Erf is still cooling, for billions of years.....
If the earth were a closed system, it would long ago have become a cold rock at least. However, the earth gets most of its energy from the sun, we’re not a closed system.
That certainly begs the questions of: How much heat energy is present from the atmosphere on down to the center of the core? What fraction of that is input from the sun per year? What fraction of that is lost to Space per year?
There is no gravity. It is a conspiracy by the elites to keep us down!
Thank goodness for transgendered single-mother bears who are not afraid of discrimination any more. No more “Yogi”.
The correct names are:
Disgi
Whoopgi
Yobian
Cisgi, and
Yodude
Actually, all the heat in the interior is due to radioactivity, right? There is no way solar radiation gets past the first few feet of the earth, and nor past the water envelope of the crust.
Isn't this well known?
From "The seven ages of a planet," 1975, William M. Kaula (1926-2000), Australian-born American geophysicist and professor at the University of California, Los Angeles.
On the basis of almost universally held assumptions concerning the formation of the planets and the isolation of the solar system from outside influences it follows rather plausibly that all terrestrial planets pass in principle through seven stages. The processes involved include the solidification of grains from gas in the condensation stage, planetesimal interactions, and formation processes. Vigorous convection processes lead to the gravitational separation of iron and the outgassing of oceans. Other stages are related to plate tectonics and terminal volcanism. The ultimate stage of quiescence is characterized by a thick lithosphere and no volcanism.
If only leftists would go into an "ultimate stage of quiescence." But I don't think the universe will last long enough for that to happen.
I’m thinking “zero”.
There have been a lot of refinements since 1975 but, the Hadean period and the great bombardmenr, while difficult to document due the scarcity of geological evidence, goes to your point. However the discoveries in plate tectonics and greater understanding of relationships among the core, mantle and crust have revised our understanding of when and how the cooling will progress. In short, there are plenty of processes keeping the heat on. Without them, we would already be like Mars. Studies like this go back a couple of billion years and find incremental changes.
Global warming is killing the volcanoes.
We must save them by crushing SUVs, killing the coal industry, and using George Soros’ railroads whenever possible.
Thanks. Isn’t the heat in the earth’s core resulting from radioactive element decay?
Radioactivity, in part, but also depth and pressure as well as convection to spread the heat around.
The primary energy source for life is the sun. Thermal vents and other earth sources are small but important in comparison.
The earth’s interior heat is due to global warming and it’s millions of degrees! https://www.youtube.com/watch?v=kGV7Dr2iDvU
Many are familiar with the Cascadia Subduction zone now in the news, where an ocean floor plate off the Pacific northwest coast is sliding under North America. As it does so, magma forms under the above Cascade mountain ranges with the result that volcanoes, like pimples, erupt from the chamber of magma below.
Those chambers of magma under the mountains are extensive and interconnected across an area of nearly a thousand miles from the Canadian Cascades down to Mt.Lasson in California.
For those who do not know, magma which never reaches topside in an eruption and is later found exposed by erosion, becomes granite (such as the batholith in Wyoming and much of the Sierra Nevada mountains in California.)
After thinking about this a bit, and doing some quick web research, it appears that the main lines of thought today say that the earth’s internal heat is mainly due to radioactivity, and the primordial heat from the formation of the planet (impacts, gravitational compression, etc.), in roughly equal amounts. (The percentages obviously cannot be quantified today; these are just estimates.)
As the contribution from radioactivity has declined through time, and the contribution from the formation of the planet cannot not change, it is likely that we had higher heat flow from the interior to the surface, thus more volcanic activity, etc.
Obviously, plate tectonics, mantle convection, etc. will complicate untangling the history of this heat flow, but it seem probable to me that a lot of the huge batholiths that date from 1.0 - 2.5 byp (especially the older ones) might be due higher heat flow from the interior of the earth, allowing more partial melting of crustal to form the huge granite implacements.
This sort of thing has always intrigued me, as I think that the deep geologic past, especially the bulk of Precambrian time, was a lot different from what we see today. The same processes occurred, but the drivers (heat flux from the interior, solar energy) and the rocks it worked on at the surface and the interior, are quite different from today. And the results were quite different from what we see today.
Add a little geothermal percolating, faulting and good luck and you’ll have the copper, gold, silver and other metal ore deposits of tomorrow (well several tomorrows down the road.
Granite is able to “float” quite nicely on the surface and is an excellent insulation so we do have some very ancient crust available but nothing but zircon contained in slightly younger sentiment or granite. So we only can model much of the Hadean crust. The ancient plutons found on North America and, particularly South Africa and Australia get you evidence of almost water like lava, kimberlite pipes and nickel deposits from before the core had assumed all its current form. I’d love to go and have a look.
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