# Tag Info

31

As Chris Mueller said, in short: it isn't, or at least highly infeasible. Projects to drill into the mantle, such as the Kola Superdeep Borehole, have all failed because drilling equipment can't withstand the heat at only ~15km deep. Even if we were to come up with some sort of cooling system that's able to cool to 6400km or 12800km deep (depending on ...

31

Probably a bit over 4 km, in this South African mine: https://en.wikipedia.org/wiki/Mponeng_Gold_Mine But as the link mentions, the mine operators go to considerable lengths to reduce the mine temperature to endurable levels from the 66°C/151°F of the surrounding rock. Note: This answer is for the original question, where the OP asked for the deepest ...

22

Matan, the continents where we all live "float" on the Earth's mantle. The continents are made out of relatively brittle rock called the "Crust" and the mantle is made out of much more ductile material. The mantle, however, is NOT liquid. It is just much more ductile than the crust so, in geologic time, it can flow (like silly putty). Also, the mantle is ...

20

Short answer: No. Long answer: Our deepest drills failed around 12km down when the drill bits were having to cope with temperatures hot enough to melt the drills. 12km down is only a tiny distance into the earth. The average distance to the center is over 6300km. So didn't even get to half of a percent of the way to the center. To do so, we'd have to ...

19

Since you termed it based on sea level, the gold mines in South Africa are not the deepest, they begin at an elevation of ~1500 m, meaning their 4 km depth is only 2.5 km below sea level. The Kidd mine in Canada is 2.9 km deep and is located at an elevation of only ~250 m above sea level making it's depth 2.65 km below sea level. https://en.wikipedia.org/...

13

One permanent threat to plate tectonics is the oceans vanishing. The scientific jury may still be out on this matter, but most geologists and geophysicists consider water to be the lubricant that makes plate tectonics possible. In a billion years or so, the Sun will have become 10% more luminous. This is conjectured to make the Earth to undergo an ...

12

There is one vaguely plausible method that has been proposed: blow open a crack in the Earth's crust using a hydrogen bomb and then fill the crack with molten iron. The iron then sinks to the core, and a small probe can sit on top of it and ride it all the way down. There's no way to get it back again, of course, but it could transmit its data back to the ...

11

It is still a little known fact that radiation play an important role in the Earth's mantle. Experiments show that mantle-material becomes transparent to infrared radiation at increasing pressures (http://www.esrf.eu/news/general-old/general-2004/earthbadro/index_html). I would also say that the mantle is currently not understood in a way where estimates of ...

10

First of all, the idea of a fixed "hotspot" reference frame is (albeit reluctantly) falling out of favour on a geological timescale; see e.g. http://onlinelibrary.wiley.com/doi/10.1029/GM121p0339/summary ("As studies of plate motions have advanced, however, it has become clear that the global hotspots do not stay fixed relative to each other...") and http://...

9

The boundary between the upper and lower mantle is today believed to be due to the phase change because of increasing pressure of: $$\text{Ringwoodite} \xrightarrow{\text{660 km, about 24.5 GPa}} \text{Mg-Perovskite} + \text{Mg-Wüstite}$$ The boundary was originally found in the form of a seismic discontinuity (the "660 km discontinuity"). This information ...

8

Is the mantle solid? It's all a matter of timescales. The mantle is undoubtedly solid (except locally in the uppermost regions where melting can occur) but on a long enough timescale it can display plastic behaviour under high temperatures and pressures, with a viscosity on the order of $\text{~}\mathrm{10^{21}~Pa~s}$ (based on estimates from isostatic ...

8

Unfortunately, you intuition about subterranean ground temperatures is incorrect. Basements and cellars do provide cooler conditions to store perishable items because the near surface rock insulates against surface heat. Go deeper however and temperature increases. Near the Earth's surface, within the crust, and away from tectonic boundaries, the rate of ...

7

Absolutely. Lithospheric flexure due to volcanic edifice emplacement is well-documented. Not only do you get isostatic depression near the volcano, but further afield you actually can have uplift due to a "hinging" sort of effect. Lithospheric flexure drives the growth of underwater coral atolls through subsidence at a recently emplaced volcano (coral forms ...

7

Yes, they can. Hawaiian Trough is a good example. The impact on thin oceanic crust is naturally larger/faster than on stiff continental crust. Generally the lithosphere will always respond to load, even if it's sediments, ice or water. The process also works the other way, exhumation by erosion ease the load and cause uplift.

7

So let's break it down part by part: He sets forth that magma is not actually created from heat / pressure buildup, etc. There is not a single mechanism for magma formation in the Earth. Magma can form by heating, decompression, infiltration of fluids (such as water), fluxing (by light elements e.g. B, F, P etc) and more. These are all well established ...

7

An arch is a poor analogy for tectonic plates. The lithosphere is supported beneath by the mantle, unlike an arch which is unsupported beneath. If the lithospheric plates were only held together only by lateral stress, friction with surrounding plates and gravity, how would they move relative to each other? How would forces at the plate interfaces vary? ...

7

Diamond isn't made of organic C at all. Organic matter would rather become oil, gas, coal or dissolve entirely. C itself isn't very common in earth's mantle, but subducted eclogites and peridotites can lead to the needed C-accumulation. But also meteorite impacts can lead to the genesis of so called micro-diamonds due to the very short lasting but extreme ...

6

Humans have difficulty visualizing how rocks flow because the required conditions are outside our everyday experience. We are familiar with surface temperatures and pressures, and geologically short time-frames, where the distinction between solid and liquid is obvious. Under very high temperatures and pressures, and especially over longer time periods, ...

6

Your intuition is quite correct: Other factors being equall, a dense magma will not rise through lighter rocks. The exception is if it is under pressure, in which case a fluid magma will escape through 'pressure release' pathways, either laterally or vertically (or in complex geologic structures, in a variety of irregular pathways). Magmas may begin to ...

6

The inner core of the Earth is a large sphere of nickel-iron alloy. Surrounding this is the molten inner core which has a temperature of approximately 5400 ℃. The source of heat that keeps the Earth's core hot and molten is the decay of radioactive elements, predominantly uranium, thorium and potassium. The Mantle and Crust act as insulators for the Earth'...

6

The mantle of Mars is heterogeneous. While there are many things that are unknown about the Martian mantle and the entire internal structure of Mars, this is not one of them. The source of this finding comes from the analysis of meteorites originating from Mars. Analysis shows that 4.5 billion years ago - when Mars was forming along with the rest of the ...

6

Borehole drifted from straight vertical by ~840 meters over 12,000 meters. All drill-bore wander side to side some and Kola borehole did not drift much until depth exceeded 5000 meters. See page 102 in the linked document. Typical rotatory drill heads designed for vertical drilling can be steer to a small degree by using a simple concept: point the bit ...

6

First, note that this plot is normalized to a reference, here the composition of CI chondrites (your version lacks the Y axis label, it's figure 2.1 from Walker 2016). So if the concentration of highly siderophile elements (HSE) seems uniform, it's partly because it is a relative concentration, not an absolute one. If you look at the raw data (Table 1.1), ...

5

Not so fast, we can't say that 'no diamond is made of organic carbon'. There are two types of diamond, based upon the relative abundance of $^{12}C$ and $^{13}C$ isotopes. The 'lighter' carbon (relatively $^{13}C$ depleted) are thought to arise from crustal carbon-bearing rocks, possibly including some organic carbon, that was subducted into the mantle, ...

5

The viscosity of the mantle varies largely with depth (because depth primarily controls temperature, pressure, and composition), but from the details of your question you seem particularly interested in the deformation time-response to large-scale changes in the stress distribution. The closest analogue to your imaginary scenario is the so called post-...

5

The mantle viscosity is likely to be non-linear, e.g., it could be as low as $10^{18} \textrm{Pa}\cdot\rm s$ (over shorter time scales) or as high as $10^{21} \textrm{Pa}\cdot\rm s$ (over longer time scales). In any case the values reported in the literature are somewhere between $10^{18}-10^{21} \textrm{Pa}\cdot\rm s$ and these are based on studies from ...

5

I'd like to add to Gordon's answer. A phase change in this context does not only refer to the change in the state of matter (e.g. liquid to solid) but a change in different solid states as well. Olivine, $\ce{(Mg,Fe)2SiO4}$, is the stable magnesian silicate in pressures down to those prevailing at a depth of ~410 km below the surface of the Earth. As the ...

5

Because it is not the strong portion that gets displaced. The mantle just below the crust bends, just like the crust above it, together they make up the lithosphere, It is not the thing being displaced it is the thing doing the displacing. The asthenosphere is being displaced. Your image is missing something important. Images courtesy of http://www....

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