Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally finds
Earth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
Tau.Neutrino said:
Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally findsEarth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
OK, so how come no-one noticed before?
Scientists, ay?
8 now, and he is on a hat-trick first ball of the 2nd innings.
stands to give round of applause
party_pants said:
8 now, and he is on a hat-trick first ball of the 2nd innings.stands to give round of applause
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+1
tauto said:
party_pants said:
8 now, and he is on a hat-trick first ball of the 2nd innings.stands to give round of applause
-
+1
+60
The Rev Dodgson said:
Tau.Neutrino said:
Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally findsEarth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
OK, so how come no-one noticed before?
Scientists, ay?
Quick reaction before I read the article. The temperature of the centre of a moon or planet is notoriously difficult to calculate. Impossible to calculate even approximately in some cases.
When it comes to the Earth, what helps is our knowledge of temperature increase with depth at the surface, seismic study of the Earth’s layers and high pressure experiments on minerals. The largest unknown is the concentration of uranium and thorium in the Earth’s inner core, which could result in an error of that magnitude. Now I’ll see if that’s what the article is about.
This is a bit of a weird article because the range of prior estimates was greater than 60 K anyway. This is just another dot point in the graph of estimates.
The Rev Dodgson said:
Tau.Neutrino said:
Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally findsEarth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
OK, so how come no-one noticed before?
Scientists, ay?
“The melting point of mantle rock — the layer between Earth’s crust and its (outer) core. While we did not necessarily set out to measure the mantle temperature, our experimental results on the melting point of mantle rock showed us the new mantle temperature. In fact, (the inner boundary of the) mantle must be 60 degrees Celsius hotter than current estimates. That’s a very significant jump.”
Perhaps I should have paid more attention to this. I had noticed that the mantle-core boundary is normally presented as a huge change in composition, not just in phase, from solid magnesium-silicate perovskite-like structure in the mantle to molten iron with impurities in the core. An immediate conclusion is that the mantle rock at the core-mantle boundary doesn’t have to melt, all it has to do is be colder than the melting temperature. What that means is that, while the new discovery is significant, it doesn’t tell us the temperature of the core-mantle boundary. All it does is give us an upper limit on the temperature of the core-mantle boundary. If the upper limit on this temperature has increased by 60 degrees then all that does is give more wiggle room for mathematical models.
“Previous experiments estimating the temperature encountered the problem of water in their synthetic rock from the atmosphere, which causes it to melt it at a lower temperature and made a rock’s melting point appear lower than it actually is. Ms Sarafian said she constructed her experiment the same as researchers before her, but added grains of olivine — which naturally occurs in the mantle — to the synthetic rock. The olivine grains would reach equilibrium with the synthetic rock, then after the experiment, we could measure the water content of the olivine grains using Secondary Ion Mass Spectrometry (SIMS) and calculate how much total water was in our experiment. This way, we could correct for the water content of our experiments and get an accurate model of the dry mantle solidus.”
Good work, but I would be extremely surprised if olivine grains could exist intact at the pressures and temperatures found at the bottom of the mantle.
mollwollfumble said:
The Rev Dodgson said:
Tau.Neutrino said:
Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally findsEarth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
OK, so how come no-one noticed before?
Scientists, ay?
“The melting point of mantle rock — the layer between Earth’s crust and its (outer) core. While we did not necessarily set out to measure the mantle temperature, our experimental results on the melting point of mantle rock showed us the new mantle temperature. In fact, (the inner boundary of the) mantle must be 60 degrees Celsius hotter than current estimates. That’s a very significant jump.”
Perhaps I should have paid more attention to this. I had noticed that the mantle-core boundary is normally presented as a huge change in composition, not just in phase, from solid magnesium-silicate perovskite-like structure in the mantle to molten iron with impurities in the core. An immediate conclusion is that the mantle rock at the core-mantle boundary doesn’t have to melt, all it has to do is be colder than the melting temperature. What that means is that, while the new discovery is significant, it doesn’t tell us the temperature of the core-mantle boundary. All it does is give us an upper limit on the temperature of the core-mantle boundary. If the upper limit on this temperature has increased by 60 degrees then all that does is give more wiggle room for mathematical models.
“Previous experiments estimating the temperature encountered the problem of water in their synthetic rock from the atmosphere, which causes it to melt it at a lower temperature and made a rock’s melting point appear lower than it actually is. Ms Sarafian said she constructed her experiment the same as researchers before her, but added grains of olivine — which naturally occurs in the mantle — to the synthetic rock. The olivine grains would reach equilibrium with the synthetic rock, then after the experiment, we could measure the water content of the olivine grains using Secondary Ion Mass Spectrometry (SIMS) and calculate how much total water was in our experiment. This way, we could correct for the water content of our experiments and get an accurate model of the dry mantle solidus.”
Good work, but I would be extremely surprised if olivine grains could exist intact at the pressures and temperatures found at the bottom of the mantle.
well, how else could they overcome the issue brought about the water content marring the results previously?
mollwollfumble said:
The Rev Dodgson said:
Tau.Neutrino said:
Earth’s interior temperature 60 degrees hotter than previously thought, student accidentally findsEarth’s interior temperature is about 60 degrees Celsius hotter than previously thought and could explain how tectonic plates move on Earth’s surface, research by a 28-year-old United States PhD student has found.
More…
OK, so how come no-one noticed before?
Scientists, ay?
“The melting point of mantle rock — the layer between Earth’s crust and its (outer) core. While we did not necessarily set out to measure the mantle temperature, our experimental results on the melting point of mantle rock showed us the new mantle temperature. In fact, (the inner boundary of the) mantle must be 60 degrees Celsius hotter than current estimates. That’s a very significant jump.”
Perhaps I should have paid more attention to this. I had noticed that the mantle-core boundary is normally presented as a huge change in composition, not just in phase, from solid magnesium-silicate perovskite-like structure in the mantle to molten iron with impurities in the core. An immediate conclusion is that the mantle rock at the core-mantle boundary doesn’t have to melt, all it has to do is be colder than the melting temperature. What that means is that, while the new discovery is significant, it doesn’t tell us the temperature of the core-mantle boundary. All it does is give us an upper limit on the temperature of the core-mantle boundary. If the upper limit on this temperature has increased by 60 degrees then all that does is give more wiggle room for mathematical models.
“Previous experiments estimating the temperature encountered the problem of water in their synthetic rock from the atmosphere, which causes it to melt it at a lower temperature and made a rock’s melting point appear lower than it actually is. Ms Sarafian said she constructed her experiment the same as researchers before her, but added grains of olivine — which naturally occurs in the mantle — to the synthetic rock. The olivine grains would reach equilibrium with the synthetic rock, then after the experiment, we could measure the water content of the olivine grains using Secondary Ion Mass Spectrometry (SIMS) and calculate how much total water was in our experiment. This way, we could correct for the water content of our experiments and get an accurate model of the dry mantle solidus.”
Good work, but I would be extremely surprised if olivine grains could exist intact at the pressures and temperatures found at the bottom of the mantle.
You can visualise the core-mantle boundary by thinking of blast furnace slag (mantle) floating on molten iron (outer core). In a blast furnace, iron melts at 1535 °C, and the blast furnace slag melts at about 1600 °C*. So the analog of the core-mantle boundary, the boundary between molten iron and solid slag in a blast furnace can be anywhere between 1535 °C and 1600 °C. It doesn’t have to be as high as 1600 °C.
In the high pressures of the Earth’s interior the temperatures will be different, but the principle remains the same.
In reading http://ethesis.nitrkl.ac.in/3868/2/output.pdf about the melting characteristics of blast furnace slag, I note that this material (and hence by analogy the inner mantle) actually has four different temperatures that can be considered “melting temperature”. From coldest to hottest these are:
IDT – Initial deformation temperature
ST – Softening temperature
HT – Hemispherical temperature
FT – Flow temperature
It would be interesting to see how the transitions through these four different temperatures affect seismic S-wave propagation (S waves pass through solid but not through liquid) and how they relate to the “melting temperature” measured in the student experiment.
> well, how else could they overcome the issue brought about the water content marring the results previously?
How do you know that the water content of lower mantle rocks is zero?
mollwollfumble said:
> well, how else could they overcome the issue brought about the water content marring the results previously?How do you know that the water content of lower mantle rocks is zero?
How would the water remain contained within the mantle? I would’ve thought that the tectonic plates ensure that the mantle and the environment within the mantle is not a closed system.
monkey skipper said:
mollwollfumble said:
> well, how else could they overcome the issue brought about the water content marring the results previously?How do you know that the water content of lower mantle rocks is zero?
How would the water remain contained within the mantle? I would’ve thought that the tectonic plates ensure that the mantle and the environment within the mantle is not a closed system.
Good answer. Would have to look at the timescale of mantle convection.