July 15, 2013
Corn Syrup-Fiberglass Model Predicts Yellowstone’s Geophysical Behavior
Brett Smith for redOrbit.com - Your Universe Online
In an experiment that could be described as a science fair exhibit on steroids, researchers from Australia and the United States have created a model explaining the geophysical processes occurring in the Pacific Northwest using corn syrup, fiberglass and a series of pistons.
Before computer models were generated using state-of-the-art processing power, scientists relied on simple models made from everyday materials. According to the international team, which published a paper in Nature Geoscience based on their work, their physical model is just as accurate as a virtual one.
"As far as we know, this is the first experiment looking at how a three-dimensional subduction zone interacts with a three dimensional plume," said co-author Christopher Kincaid, a Professor of Oceanography and geophysical fluid dynamics expert with the University of Rhode Island.
The team used their model to replicate some of the geophysical processes under Yellowstone National Park - a region with geothermal features that fascinate tourists and scientists alike. Researchers still aren't completely sure what drives the volcanic activity behind the park's geysers and hot springs.
Previous theories have cited a mantle plume, which brings heat from the Earth's core toward the surface. However, a conventional plume has a head where lava comes to the surface and a tail, which creates a younger volcanic track - like those seen in the Hawaiian Islands. Citing a 180-mile offset between a lava outpouring along the Columbia River and younger rocks of the Snake River Plain, some experts dismiss the traditional plume model in the case of Yellowstone.
To model the region's geophysical dynamics, Kincaid and his colleagues went to visit a 3D plate tectonics model at the Australian National University. While there, the team heated thick corn syrup to a consistency that replicated fluid activity in the Earth's mantle and then injected it into the model. The system was kept at zero degrees Celsius to create a cold membrane on the exterior of the syrup, replicating Earth's lithospheric plates.
With 1 minute equaling 4 million years and a 1-centimeter per minute flow rate equivalent to 10 kilometers per million years, the system eventually resembled the pattern of volcanism observed in the Pacific Northwest in the form of a bifurcated, or split, plume.
The model showed one half drawn down into the subduction zone, where two tectonic plates meet, while the other half moved north, rising to the surface like the lava flows seen near the Columbia River. The modeled plume's tail sat along where the Snake River Plain would be - as predicted.
"Right off the bat we found that if you put a plume in to the north of the symmetry axis of the subduction zone, it gets ripped apart and deformed by the flow fields being produced by the subduction zone," Kincaid said.
"This is the first quantitative study on the interaction between the mantle plume and the subduction zone," Lijun Liu, a geodynamicist at the University of Illinois at Urbana-Champaign, said in reaction to the news of the study. "Previous work has mainly focused on either a plume or subduction, not the combination of the two."
"Subduction zones are like giant attractors that pull everything toward them," Kincaid explained. "The interaction between the plume and the subduction zone makes the plume behave differently and look different than what it says in the textbook."