Europium points to new suspect in continental mystery

first_imgShare7Jeff [email protected]  Jade [email protected] points to new suspect in continental mysteryStudy: Rare earth element implicates garnet for continents’ missing ironHOUSTON — (May 16, 2018) — Clues from some unusual Arizona rocks pointed Rice University scientists toward a discovery — a subtle chemical signature in rocks the world over — that could answer a long-standing mystery: What stole the iron from Earth’s continents?The find has weighty implications. If the iron content of continental rocks was a bit greater, as it is in the rocks beneath Earth’s oceans, for example, our atmosphere might look more like that of Mars, a planet so littered with rusty, oxidized rocks that it appears red even from Earth. Return to article. Long DescriptionA garnet pyroxenite xenolith from Sierra Nevada, Calif. (Image courtesy of C. Lee/Rice University)“There is a relationship between iron depletion and the garnet fractionation signatures, which means magmas that fractionate more garnet are more depleted in iron,” Tang said. “This is born out in the global record, but the evidence is something that wouldn’t be obvious from looking at just one or two cases. It’s the kind of thing that requires a global database, and those have only recently become available.”Lee said the find has important implications for Earth’s ability to sustain an oxygen-rich atmosphere.“Photosynthesis produces oxygen, but the primary thing that takes oxygen out of circulation for a long time is oxidation with the crust,” Lee said. “If what comes out of volcanoes to form the continents is effectively already rusted, then it won’t immediately react with and deplete the oxygen in the atmosphere.”After submitting their results for peer-reviewed publication, Tang and Lee found that renowned Australian petrologist Ted Ringwood and colleagues had implicated garnet rather than magnetite in a few papers published 50 years ago.“Many of the people in our field have a scientific lineage that goes back to Ringwood,” Lee said. “I’m sure many of them may take one look and think this is a crazy idea, but considering that their great-great-grandfather, academically speaking, had speculated on this, perhaps we’re in good company.”The research was supported by a Frontiers of Earth Systems and Dynamics grant from the National Science Foundation.-30-High-resolution IMAGES are available for download at: The Cordillera Huayhuash in the Peruvian Andes as seen from the International Space Station in May 2008. (Image courtesy of ISS Expedition 17/NASA)” alt=”last_img” />