New seismic maps of the region’s mantle could lead to better predictions of what will happen to the Antarctic ice sheet because of warming temperatures and global climate change, according to research published recently in the Journal of Geophysical Research: Solid Earth.
The maps were created by Andrew Lloyd, a graduate student in earth and planetary sciences at Washington University in St. Louis, and use data collected from instruments placed across the West Antarctic Rift System and Marie Byrd Land in 2009 and 2010.
According to the university, the study marks the first time that seismometers durable enough to withstand the harsh winter conditions found in these parts of Antarctic have been used to record earthquake-related activity there—and the first time that the region’s mantle was mapped.
The instruments recorded reverberations of distant earthquakes from January 2010 to January 2012, and once that data was collected by Lloyd’s team, they used it to create maps of seismic velocities beneath the rift valley in these parts of the planet’s southernmost continent.
Findings suggest there may be a hidden mantle plume
They discovered a mass of superheated rock about 60 miles below Mount Sidley, which is part of a chain of volcanic mountains in Marie Byrd Land at one end, as well as heated rock located beneath the Bentley Subglacial Trench, a deep basin at the opposite end of the transect.
Mount Sidley, the study authors explained, is the highest volcano in Antarctic and rests directly above a hot spot in the mantle. It is also the southernmost mountain in a volcanic range in Marie Byrd Land, a mountainous region near the coast of West Antarctica.
“A line of volcanoes hints there might be a hidden mantle plume, like a blowtorch, beneath the plate,” said Dr. Doug Wiens, a professor of earth and planetary sciences at WUSTL and one of the study’s co-authors. “The volcanoes would pop up in a row as the plate moved over it.”
However, he admitted that it is “a bit unclear” if that’s what’s actually taking place. One thing that is certain, however, is that the heat flow into the base of the ice sheet is higher in this area. The discovery of a hot zone beneath the Bentley Subglacial Trench was a bit of a surprise, said Lloyd, as it’s the lowest point on Earth that’s not covered by an ocean.
“We didn’t know what we’d find beneath the basin. For all we knew it would be old and cold,” Dr. Weins said. “We didn’t detect any earthquakes, so we don’t think the rift is currently active, but the heat suggests rifting stopped quite recently.” This activity could help explain why heat flow in some parts of Antarctic are four times higher than the global average, he added.
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Feature Image: Thinkstock
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