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A Brown University study provides new evidence that the icy shell of Jupiter's moon Europa may have plate tectonics similar to those on Earth. The presence of plate tectonic activity could have important implications for the possibility of life in the ocean thought to exist beneath the moon's surface.

The study, published in Journal of Geophysical Research: Planets, uses computer modeling to show that subduction -- when a tectonic plate slides underneath another and sinks deep into a planet's interior -- is physically possible in Europa's ice shell. The findings bolster earlier studies of Europa's surface geology that found regions where the moon's ice shell looks to be expanding in a way that's similar to the mid-ocean spreading ridges on Earth. The possibility of subduction adds another piece to the tectonic puzzle.

"We have this evidence of extension and spreading, so the question becomes where does that material go?" said Brandon Johnson, an assistant professor in Brown's Department of Earth, Environmental and Planetary Sciences and a lead author of the study. "On Earth, the answer is subduction zones. What we show is that under reasonable assumptions for conditions on Europa, subduction could be happening there as well, which is really exciting."

Part of the excitement, Johnson says, is that surface crust is enriched with oxidants and other chemical food for life. Subduction provides a means for that food to come into contact with the subsurface ocean scientists think probably exists under Europa's ice.

"If indeed there's life in that ocean, subduction offers a way to supply the nutrients it would need," Johnson said.

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Category: Science