Visitors Now:
Total Visits:
Total Stories:
Profile image
By Alton Parrish (Reporter)
Contributor profile | More stories
Story Views

Now:
Last Hour:
Last 24 Hours:
Total:

Popcorn-Rocks Solve the Mystery of The Magma Chambers

Thursday, November 3, 2016 6:45
% of readers think this story is Fact. Add your two cents.

(Before It's News)

A magma chamber is a large underground pool of liquid rock found beneath the surface of the Earth. The molten rock in such a chamber is under great pressure, and given enough time, that pressure can gradually fracture the rock around it creating outlets for the magma.
 
 If it finds a way to the surface, then the result will be a volcanic eruption; consequently, many volcanoes are situated over magma chambers. Magma chambers are hard to detect, and most of the known ones are therefore close to the surface of the Earth, commonly between 1 km and 10 km under the surface. In geological terms, this is extremely close to the surface, although in human terms, it is considerably deep underground.
 

Since the 18th century, geologists have struggled to explain how big magma chambers form in the Earth’s crust. In particular, it has been difficult to explain where the surrounding rock goes when the magma intrudes. Now a team of researchers from Uppsala University and the Goethe University in Frankfurt have found the missing rocks – and they look nothing like what they expected.

B4INREMOTE-aHR0cHM6Ly80LmJwLmJsb2dzcG90LmNvbS8tN3FJaDdXOGhqSmsvV0JzMktVdkNhZkkvQUFBQUFBQUJRSEkvcElKWGx5d2NyNDhQTWw0c2tra0FXVWIyU3pwMDNXVFVRQ0xjQi9zNjQwLzEyNjEwN193ZWIuanBn
Credit: Börje Dahrén
Researchers have previously proposed that the roofs and walls of magma chamber were either melted and assimilated into the magma, or that they would sink to the bottom of the magma chamber. However, enough evidence for either of these hypotheses have not been forthcoming, and researchers now propose a third possibility.

“We show that rock fragments from the roof of the magma chambers could have been expelled, similar to popcorn that is thrown out of a hot pan! We have found them in rocks that have been ejected in volcanic eruptions. The rock fragments are full of bubbles and have very low densities, and they look a lot like popcorn,” says Steffi Burchardt, researcher at the Department of Earth Sciences, Uppsala University.

 
This is Steffi Burchardt in front of Payun in Argentina.
B4INREMOTE-aHR0cHM6Ly8xLmJwLmJsb2dzcG90LmNvbS8tSlNldFlueDVjX1EvV0JzMmRWNTJOREkvQUFBQUFBQUJRSE0vWk1VWmxIcmVTOEkzeXdDLVU0UmdGT0lIRC1uNjNwd1V3Q0xjQi9zNjQwLzEyNjEwOF93ZWIuanBn

Credit: Karen Mair

When rock fragments fall into the magma chamber, they are rapidly heated by several hundred degrees, and all fluids inside boil instantly. This is similar to what happens when a grain of corn is put into the pan and the water inside boils – and we get popcorn.

Steffi and her colleagues have now managed to show how the popcorn-effect makes the rock fragments float and rise to the top of magma chambers rather than sink to the bottom. The floating rock fragments are then found among the erupted volcanic rocks, instead of inside the frozen magma chambers as previously expected. Furthermore, the gases released from the rock fragments as they boil also contribute to a higher pressure in the magma which can help explain some of the more explosive eruptions.

“Sometimes you can find the solution to age-old puzzles by looking in new places – in this case literally looking outside the box! The frozen magma chambers proved to be the wrong place to look,” Steffi Burchardt explains.

 
 
Contacts and sources:

Steffi Burchardt

Uppsala University
 

Citation: Erupted frothy xenoliths may explain lack of country-rock fragments in plutons Steffi Burchardt, Valentin R. Troll, Harro Schmeling, Hemin Koyi & Lara Blythe Scientific Reports 6, Article number: 34566 (2016) doi:10.1038/srep34566 http://dx.doi.org/10.1038/srep34566

Report abuse

Comments

Your Comments
Question   Razz  Sad   Evil  Exclaim  Smile  Redface  Biggrin  Surprised  Eek   Confused   Cool  LOL   Mad   Twisted  Rolleyes   Wink  Idea  Arrow  Neutral  Cry   Mr. Green

Top Stories
Recent Stories

Register

Newsletter

Email this story
Email this story

If you really want to ban this commenter, please write down the reason:

If you really want to disable all recommended stories, click on OK button. After that, you will be redirect to your options page.