Earth’s mantle is the thick layer of silicate rock between Earth’s crust and its molten core, making up about 84% of our planet’s volume.
Earth’s mantle is the thick layer of silicate rock between Earth’s crust and its molten core, making up about 84% of our planet’s volume. The mantle is predominantly solid but, on geologic time scales, it behaves as a viscous fluid — as difficult to stir and mix as a pot of caramel.
But, sticking with candy comparisons, maybe think more about malt balls and not gooey caramels. A new study from Washington University in St. Louis suggests that the deep part of the ancient mantle closest to the Earth’s core started out substantially drier than the part of the mantle closest to the young planet’s surface.
By analyzing noble gas isotope data, Rita Parai, assistant professor of earth and planetary sciences in Arts & Sciences, determined that the ancient plume mantle (the deep part) had a water concentration that was a factor of 4 to 250 times lower when compared with the water concentration of the upper mantle.
The resulting viscosity contrast could have prevented mixing within the mantle, helping to explain certain long-standing mysteries about Earth’s formation and evolution. The research is published the week of July 11 in the Proceedings of the National Academy of Sciences (PNAS).
Read more at Washington University in St. Louis
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