Water in Earth’s Deep Mantle

Posted on February 13, 2007  Comments (1)

3-D seismic model of vast water reservoir revealed:

n analyzing the data, Wysession first saw large patterns associated with known areas where the ocean floor is sinking down into the earth. Beneath Asia, the fallen Pacific sea floor piles up at the base of the mantle. Right above that he observed an “incredibly highly attenuating region, that is both very damping and slightly slow,” he said. “Water slows the speed of waves a little. Lots of damping and a little slowing match the predictions for water very well.”

Previous predictions calculated that a cold ocean slab sinking into the earth at 1,200 to 1,4000 kilometers beneath the surface would release water in the rock that would escape the rock and rise up to a region above it, but this was never previously observed.

“That is exactly what we show here, the exact depth and high attenuation amounts right above it,” Wysession said. “I call it the Beijing anomaly. Water inside the rock goes down with the sinking slab and it’s quite cold, but it heats up the deeper it goes, and the rock eventually becomes unstable and loses its water. The water then rises up into the overlying region, which becomes saturated with water.

“If you combine the volume of this anomaly with the fact that the rock can hold up to about 0.1 percent of water, that works out to be about an Arctic Ocean’s worth of water.”

One Response to “Water in Earth’s Deep Mantle”

  1. CuriousCat: Himalayas Geology
    February 25th, 2008 @ 3:18 pm

    “When the massive slab – up to eight times the area of the UK and as thick as a dozen Everests on top of each other – dropped off, the lighter crust above it rebounded upwards like a cork released under water…”

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