Iron meteorites likely hidden below Antarctic ice

by Lucas Joel
Thursday, June 16, 2016

Antarctica has yielded two-thirds (about 35,000) of all the meteorites that have ever been discovered on Earth. Credit: NASA.

Despite the fact that meteorites fall relatively evenly across the surface of the planet, most meteorites retrieved by humans have come from Antarctica. This is because meteorites are easily buried and preserved in Antarctic ice; over time, the ice melts and exposes the dark-colored fallen rocks for relatively easy recovery on the continent’s white surface. But iron-rich meteorites, common among specimens found in other parts of the planet, are unusually rare in Antarctica. Researchers may now have figured out why.

After meteorites are buried in Antarctica, they are sometimes transported back to the surface by upwelling glacial ice in regions known as Meteorite Stranding Zones (MSZ). Meteorites “transported up toward the surface of a MSZ will be exposed to an increasing level of solar warming,” wrote mathematician Geoffrey Evatt of the University of Manchester in England and colleagues in a new study in Nature Communications. “If the rising meteorite could reach a shallow-enough depth for the solar energy to enable melting of its surrounding ice, the meteorite would sink relative to the upwelling ice.” Iron-rich meteorites, being more efficient conductors of heat than stony meteorites, called chondrites, may thus melt and sink preferentially, the authors explained.

Knowing where to look for iron-rich meteorites and retrieving them has the potential, the authors noted, to help us better understand the chemical makeup of the early solar system from which the rocks likely originated.

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