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  • Scientists have thought for a while now that there may be water trapped within the earth's

  • mantle.

  • Yeah, a secret ocean--underneath our oceans--inside the earth!

  • This would change our common understanding of what the earth looks like on the inside.

  • Now, there's new evidence that provides even more support for this idea, and has geoscientists

  • of all kinds wondering how Earth's hidden oceans could have formed.

  • And get this--the new evidence...it's diamonds.

  • Back in 2014, scientists discovered diamonds that contain water-bearing minerals.

  • These diamonds were brought up into human range from deep within the earth's transition

  • zone, around 400 miles below the earth's surface, so this was pretty remarkable.

  • How did water get trapped in something that far down?

  • Well, when we're talking about water here, we're not talking about the liquid water

  • we're familiar with.

  • They're actually the different elements that make UP water--hydrogen and oxygen--bound

  • into the crystalline structure of a solid mineral, which is where we get water-bearing

  • minerals.

  • See, the earth's mantle moves by convection, meaning hot magma rises and pushes other parts

  • of the mantle down further into the earth.

  • When these water-bearing minerals get pushed down because of this convection activity,

  • the increased pressure literally wrings the water out of them--this time, as water we

  • would probably recognize.

  • The initial conjecture that there might be some water deep within the earth was confirmed

  • by the 2014 diamond discovery, and then backed up with seismic data.

  • The seismic readings were consistent with the idea that there was water in the mantle,

  • and it contributes to the mantle's behavior.

  • More recently?

  • Even more diamonds!

  • These new jewels pulled from the earth's depths actually do contain water...but in

  • a TOTALLY new form that we've never observed before.

  • These diamonds, from several locations across southern Africa and China, contain tiny inclusions

  • of a form of water called ice-VII, an extremely high pressure form of water that scientists

  • refer to as water-ice . This is the first time we've ever actually observed this form

  • of water in nature.

  • The researchers say these new diamonds support the presence of, at least what they're calling,

  • 'aqueous pockets' of water throughout the mantle.

  • So not only is there water DEFINITELY inside the earth, but also, it may be in a totally

  • novel form of water.

  • Who knew water came in different forms?!?

  • I feel like that leads us to two important questions: 1.)

  • So what?” and 2.)

  • How did it get there?”

  • Well, one answer kind of addresses both.

  • The main theory for how we have water on earth at all is that it got brought to us by rogue

  • asteroids containing water-bearing minerals crashing into us from the far-reaches of our

  • solar system.

  • The theory goes that when the earth was forming, our solar system was probably too hot for

  • any water molecules to survive and cling to the space dust that would become the earth,

  • so water had to have been brought to us from off-planet after the earth formed.

  • But these new diamonds could upend that.

  • Some scientists now estimate that the mantle might contain more water than all the earth's

  • oceans combined, which is way more water than could have been pulled, via convection, from

  • the surface of the earth into the mantle in the given time frame.

  • We may need to re-examine our theories about the state of the solar system at the time

  • the earth was forming--maybe it was possible for water to survive and cling to dust and

  • rock as it coalesced to form the earth.

  • Maybe there's an entirely different theory that we haven't thought of yet!

  • We're still unsure of the exact amount of water in the mantle though, or what form it

  • might be in.

  • Scientists plan to keep exploring, though, both with seismic measurements and lab experiments

  • that try to simulate the materials and pressures that we would find inside the earth.

  • And, of course, keep looking for and examining diamonds--not the kind you want to put in

  • a ring, but of course the kind that contain hydrous minerals.

  • A girl's true best friend.

  • Fun fact: the materials that primarily make up the earth's mantle are called Wadsleyite

  • and Ringwoodite, both water-bearing minerals whose structure leaves them prone to gapping,

  • letting researchers think of them a bit like a sponge that's holding the mantle's water.

  • For more awesome earth science, subscribe to Seeker, and check out this video here about

  • the massive asteroid currently headed for earth.Thanks for watching!

Scientists have thought for a while now that there may be water trapped within the earth's

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A New State of Water Reveals a Hidden Ocean in Earth’s Mantle

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    joey joey に公開 2021 年 04 月 15 日
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