Imagine drifting on the icy stretch of Antarctica. A white continent stretches below you, and it is smothered in enough icy water to drown each and every coast of the world in a wave of 216 feet (66 meters) if it were to melt. But scientists now believe that, deep under almost 2 kilometers of ice and a relatively thin slice of rocky crust, a frozen region of the continent is hiding a column of red magma, stretched to the surface, according to a new study.
Usually, the magma approaches the surface only on the edges of the tectonic plates. And Marie Byrd Land of West Antarctica, where the plume is believed to exist, is far from these border regions. However, there are places in the world where magma reaches the surface away from tectonic border regions, NASA scientists said in a statement on Nov. 7. Yellowstone National Park is one of them. Hawaii is another. All this magma pushes against the crust in these parts of the world, causing it to swell and pump heat through the ground.
This heat gave scientists early clues that the Antarctic plume exists. [Photo Album: Antarctica, Iceberg Maker]
Despite its apparent calm, the Antarctic is alive with the movement. Huge masses of frozen water slide, slide and move with enormous pressure against the continent below, their constant movement being lubricated by a complex system of rivers and lakes under the ice.
But in Marie Byrd Land, researchers found even more of this activity than known regional heat sources could explain. Something else was cooking the ice shelf. About 30 years ago, researchers began to suspect that a plume of magma could be the cause, given the dome-shaped crust in this region.
Now scientists know for sure.
Investigators in the study Hélène Seroussi and Erik Ivins of NASA's Jet Propulsion Laboratory built a model of all known melting and freezing under the ice in the region. Researchers do not have probes under ice, but they can detect activity thanks to meticulous measurements of the rise and fall of NASA's ICESat satellite surface and IceBridge flyover missions . [Extreme Antarctica: Amazing Photos of Lake Ellsworth]
Their model confirmed the existence of a plume of magma pumping out about 150 milliwatts per square meter (or about 11 square feet) of heat up to the surface, and reaching up to 10 percent. at 180 milliwatts per square meter in a region where a fault in the crust may exist. (A milliwatt is one-thousandth of a watt.) For comparison, a typical land extent in the United States receives about 40 to 60 milliwatts per square meter of geothermal heat, and Yellowstone receives about 200 milliwatts per square meter.
This magma plume is not another possible cause of recent increases in the melting of the western Antarctic icecap attributed to man-made climate change. . The plume is much older than the recent period of atmospheric warming; Indeed, between 50 and 110 million years ago, it is older than our species and the western Antarctic ice sheet itself. The plume has played a role in the behavior of the ice cap throughout its history, and recent outbreaks in the melt are the result of all the extra heat that humans have pumped into it.
The study was published online Sept. 4 in the Journal of Geophysical Research: Solid Earth.
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