Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Squeezing out mountains, mathematically, on Jupiter's moon Io

18.05.2016

Novel mountain-building mechanism on Io may also have operated on early Earth

Mountains aren't the first thing that hit you when you look at images of Jupiter's innermost moon, Io. But once you absorb the fact that the moon is slathered in sulfurous lava erupted from 400 active volcanoes, you might turn your attention to scattered bumps and lumps that turn out, on closer inspection, to be Io's version of mountains.There are about 100 of them, and they don't look anything like the low lying volcanoes.


A thrust fault rips to the surface of a numerical Io. As it breaches the surface, it pulls on the overhanging crustal block (to the left of the fault), and 'extensional' features such as trenches called graben form there. The fault also provides a conduit for rising magma and collapsing magma chambers form 'patera', or depressions on the surface. The stair-stepping is an artifact; the simulation divides the crust into small elements so that simpler (solvable) functions can be used to describe the rock mechanics.

Credit: Bland and McKinnon

They also don't look like mountains on our home world. While we favor majestic ranges stretching from horizon to horizon, the mountains on Io are isolated peaks of great height that jut up out of nowhere. From space, they look rather like the blocky chips in the fancier kind of chocolate chip cookie.

For planetary geophysicists like William McKinnon, professor of earth and planetary science in Arts & Sciences at Washington University in St. Louis, the mountains of Io are an intriguing puzzle. By what process consistent with everything that is known about Io could these bizarre mountains have formed?

Since Io buries the evidence of its tectonic processes under a continually refreshed coating of lava (adding 5 inches a decade), the scientists have turned increasingly to computer simulations to solve the problem. In the May 16 online advance issue of Nature Geoscience, McKinnon and Michael T. Bland, a research space scientist at the USGS Astrogeology Science Center in Flagstaff, Ariz., publish a computer model that is able to make numerical mountains that look much like the jutting rock slabs on Io.

Putting the squeeze on

"The planetary community has thought for a while that Io's mountains might be a function of the fact that it is continuously erupting lava over the entire sphere," McKinnon said. "All that lava spewed on the surfaces pushes downward and, as it descends, there's a space problem because Io is a sphere, so you end up with compressive forces that increase with depth."

McKinnon and his former student, Paul Schenk, now at the Lunar and Planetary Institute in Houston, wrote a paper explaining this hypothesis in 2001.

The numerical experiment described in Nature Geoscience tests this hypothesis through simulation. "People have been squeezing planetary interiors forever to see what happens," McKinnon said, "but we're applying the squeeze differently, because on Io compression increases with depth; the surface is not in compression. We thought we could mimic this by beveling in the edges of a box, squeezing it as you might an accordion.

The simulations show that the strain localizes to a single fracture, or fault, that starts deep in the lithosphere and rips through the rock all the way to the surface. When it breaches the surface, it actually overshoots, forming a scarp, or cliff, and stretching the surface of the overhanging block.

"It's a neat demonstration of how things might actually work," McKinnon said.

It might explain, for example, why there are often recent eruptions near mountains.

"The compressive forces deep in the crust are incredibly high," Mckinnon said. "When these faults breach the surface, those forces are released, and the entire stress environment around the fault changes, providing a pathway for magma to erupt."

The model might also explain why the mountains are associated with shallow, irregular depressions called patera. "When the stress environment changes," McKinnon said, "a magma chamber can form at midlevel in the crust. When this magma surfaces along the fault, the crust above the chamber collapses, forming the patera."

The model of mountain building also explains some of the "extensional" tectonic features on Io, such as "pull apart" mountains. These are mountains that have split in two parts that have shifted with respect to one another.

It might even explain a subtle feature of Io: the anti-correlation between mountains and volcanoes.

"If you look at a big map of Io," McKinnon said, "there are concentrations of mountains and concentrations of volcanoes, and they kind of nest into one another. Even though mountains and volcanoes are often found together, if you look at all of the mountains and all of the volcanoes, they're anti-correlated. It's a peculiarity of Io."

Why might this be? It's not just the increasing weight of the overlying lava that puts the deep crust in compression McKinnon said, but also the increasing temperature. "Heating at depth causes the rocks to want to expand, and since there's no room to expand, you again get compressive forces," he said.

As long as the volcanoes are erupting, they carry this heat away and thermal stresses are low, reducing the likelihood of mountain formation. But if volcanism stops, the crust heats up, thermal stresses increase, and mountain formation becomes more likely.

Was Earth once like Io?

If all of this seems very alien, it is. "It's a novel mountain-forming mechanism that we don't see elsewhere in the solar system," McKinnon said.

"But the same kind of thing could have happened on Earth, when it was very young and entirely covered by a shallow ocean," McKinnon said.

"Because there was still lots of volcanism, mountains like those on Io might have burst through the ocean. They might have been the first emergent land on Earth," McKinnon said.

So Io might be a time portal to the early Earth.

###

"Mountain building on Io driven by deep faulting," Nature Geoscience, published online May 16, 2016. doi:10.1038/ngeo2711 This work was supported by NASA's Planetary Geology and Geophysics Program (NNX11AP16G) and Solar System Workings Program (NNH15AZ801).

Media Contact

Diana Lutz
dlutz@wustl.edu
314-935-5272

 @WUSTLnews

http://www.wustl.edu 

Diana Lutz | EurekAlert!

More articles from Physics and Astronomy:

nachricht Shape matters when light meets atom
05.12.2016 | Centre for Quantum Technologies at the National University of Singapore

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

IHP presents the fastest silicon-based transistor in the world

05.12.2016 | Power and Electrical Engineering

InLight study: insights into chemical processes using light

05.12.2016 | Materials Sciences

High-precision magnetic field sensing

05.12.2016 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>