Giant blob of superheated rock under West Antarctica

A new seismic survey shows there is a blob of superheated rock 60 miles below West Antarctica. To describe it, the researchers use the phrase “like a blow-torch”. Of course, just because the parts of Antarctica that are warming are near or over this hot blob does not mean it’s causing the melting. It could be a coincidence. ; -)

… this is the first detailed look at the Earth beneath this region.

Not surprisingly, the maps show a giant blob of superheated rock about 60 miles beneath Mount Sidley, the last of a chain of volcanic mountains in Marie Byrd Land at one end of the transect. More surprisingly, they reveal hot rock beneath the Bentley Subglacial Trench, a deep basin at the other end of the transect.

The Bentley Subglacial Trench is part of the West Antarctic Rift System and hot rock beneath the region indicates that this part of the rift system was active quite recently.

The study really highlights how little we know about heat flow in Antarctica:

While heat flow through the Earth’s crust has been measured at at least 34,000 different spots around the globe, in Antarctica it has been measured in less than a dozen places. In July 2015, scientists reported the heat flow at one of these spots was four times higher than the global average.

Ever since then, scientists have been wondering why the reading was so high. “Recent extension in the Bentley Subglacial Trench might explain these readings,” Wiens said.

The IPCC says the West Antarctic is melting thanks to CO2.

Though they can’t explain why the rest of Antarctica doesn’t appear to be melting as well.

Naturally we don’t have any idea if the heat flows have gotten stronger lately since we didn’t know about the hot rocks before, and rather oddly, the volcanoes are going in the “wrong direction”:

“A line of volcanoes hints there might be a hidden mantle plume, like a blowtorch, beneath the plate,” said Doug Wiens, PhD, professor of earth and planetary sciences and a co-author on the paper. “The volcanoes would pop up in a row as the plate moved over it.”

“But it’s a bit unclear if this is happening here,” he said. We think we know which direction the plate is moving, but the volcanic chain is going in a different direction and two additional nearby volcanic chains are oriented in yet other directions.

The Full press release

REFERENCE

Lloyd et al (2015) A seismic transect across West Antarctica: Evidence for mantle thermal anomalies beneath the Bentley Subglacial Trench and the Marie Byrd Land Dome. Journal of Geophysical Research: Solid Earth, 2015; DOI: 10.1002/2015JB012455

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