Questions tagged [mantle]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
3
votes
1answer
119 views

Why Earth's outer core does not dissolve into the mantle?

It is well accepted that the outer core is made out of liquid iron and nickel, and as everything else it should tend to reach chemical equilibrium with its surrounding. In particular, I would expect ...
0
votes
1answer
39 views

How is the difference in crust and mantle composition explained?

We know that the composition of the crust is SiAl and SiMa and the one of mantle is mostly ophiolites, but why? Which are the geological processes that make this difference exist?
19
votes
4answers
8k views

What is the deepest we have ever gone into the Earth?

I remember Journey to the Center of Earth and wonder: What is the deepest in the Earth surface or below sea level we have traveled either by foot, sub, drill or camera?
2
votes
1answer
90 views

Why the “Mission to Earth’s core” proposal suggests using liquid iron instead of lead?

Nature communications article "Mission to Earth's core — a modest proposal", suggests placing a large volume of liquid iron in a crack and let it sink all the way to the Earth's core, carrying along a ...
1
vote
0answers
17 views

Equations for Mantle Flow and Isostatic Rebound

In my Geomorphology book there is a section on uplift caused by isostatic rebound and it goes over how the viscoplastic nature of the mantle and the mechanically detached asthenosphere allow a long ...
3
votes
0answers
31 views

What is the minimum temperature difference to drive mantle convection?

The condition for convection to cease is that the Rayleigh number $$\mathrm{Ra}=\frac{g\rho\alpha L^3\Delta T}{\kappa\nu}\lessapprox 10^3.$$ For the Earth's mantle I have seen estimates of $\mathrm{Ra}...
5
votes
0answers
40 views

By how much did the Earth's diameter decrease due to cooling, if at all, since it was formed?

The answer to How long until Earth's core solidifies? question cites an estimation that the Earth (as a planet, not the surface of it) has cooled down by about 250K since it was formed. The question ...
0
votes
2answers
67 views

Phase relation for mantle?

I have information about temperature, pressure, normal and shear stresses, viscosity, conductivity, density, heat capacity and adiabatic heating for a particular area of mantle in the form of 2D ...
6
votes
4answers
1k views

Are all natural diamonds made of organic carbon material?

I've read that diamonds are created at a depth of about 180 km. By volcanic activity it comes above. But did plants and trees of 300 million years ago sink so deep? Or is it possible that inorganic ...
3
votes
1answer
119 views

Why is the Lithosphere-Asthenosphere Boundary an Isotherm?

My understanding of the LAB is that it represents the point in the earth where the mantle undergoes a temperature activated mechanical change. The temperature of the boundary depends on the melting ...
3
votes
1answer
39 views

Do there exist reasonable numbers on the density/radius/mass of the various geological layers of the Earth?

I've been doing some math on the radius of the core (inner core in particular), and I keep getting what look like nonsense results. The composition is supposedly nearly all iron, close enough to it ...
12
votes
3answers
3k views

What do continents “lay” on?

It's a simple question.. What do continents "lay" on? Do they float on water? or are they huge bodies that "emerge" from the sea floor/bed? are they connected to the bottom of the oceans? Hope the ...
1
vote
0answers
105 views

Mass balance for calculating mantle composition

I've seen some problem sets given without answers / solutions regarding how to calculate the composition of the mantle given solar composition (and assuming the same would apply to the Earth). For ...
3
votes
2answers
98 views

Need help understanding what an “isostatic model minimizing crustal deviatoric stress” means

Despite the background information coming from another body besides the Earth, the terms I would like to understand are historically geophysical in nature. Background: I just read today's news "...
1
vote
1answer
356 views

How can isostatic compensation of the crust be reconciled with a relatively strong upper mantle?

As I understand it, the outer portion of the Earth can be divided into the crust and mantle on chemical grounds (separated by the Moho), or into the lithosphere and asthenosphere based on mechanical ...
7
votes
2answers
358 views

What fraction of Earth's crustal material survives the supercontinent cycle?

I know that things are not as simple, but for the sake of argument I'll assume a supercontinent cycle of $\sim$400 Myr periodicity is active on Earth. If that is the case, then my naive ...
8
votes
2answers
889 views

What is meant by phase-change in mantle?

Phase transition usually means changing from liquid to solid phase. But in geology literature we come across transitions from one mineral to other mineral. For example olivine-spinel transition at 410 ...
7
votes
1answer
576 views

How straight is the Kola superdeep borehole?

The legendary Kola superdeep borehole is about 12 km deep. To achieve such depth, a major difficulty is to make sure the borehole is vertical straight. Intuitively, when the borehole is deep enough, ...
4
votes
1answer
490 views

What's up with the “jelly sandwich” analogy of the lithosphere, asthenosphere and mesosphere?

Here's what I know: The lithosphere is hard because it is cold and low-pressure. The asthenosphere is more deformable because of higher temperatures and pressures. The mesosphere is below the ...
14
votes
4answers
6k views

Can we really travel through earth's core?

Inspired by the movie, "The Core". Can we really travel through earth's core? I will provide 2 sub questions: Is there any substance that can resist the heat of earth's core? Between the crust and ...
3
votes
2answers
128 views

Why do buoyantly rising mantle minerals melt, yet buoyantly rising atmospheric waters condense?

In the mantle, minerals contained in buoyant plumes of rock undergo phase changes from solid to liquid (decompression melting). In the atmosphere, waters contained in buoyant plumes of air undergo ...
2
votes
0answers
68 views

What is the structure of the hot spot under Hawaii?

The Hawaiian Islands are formed by volcanic activity over a hotspot in the Earth's mantle. What is the shape of this hotspot in the mantle? Is it like a pyramid or a pillar or an upside-down pyramid?
16
votes
2answers
2k views

At what point does plate tectonics stop?

As the core and mantle of the earth cools, it will reach a point where new crust cannot be produced. How can this point be calculated? If we can, has anyone done such calculations? Thanks!
8
votes
1answer
124 views

Magma resultant from group 1 and group 2 elements?

I was recently speaking with a geology professor over lunch at a university who has a theory that I've never heard before. His postulation was quite compelling and I was hoping to do a little digging ...
2
votes
2answers
1k views

Which one is the correct concept of Continental Crust and Oceanic Crust?

I knew so far that, the classification of crust as SiAl-SiMa, vs. classification of crust as Continental-Oceanic; are completely different, as told in my school geography and university paleobiology ...
2
votes
2answers
778 views

How is dense magma able to rise and punch through continental crust?

I am trying to understand how a dense basaltic lava is able to rise and punch through the continental crust, such as in mantle plumes or the Great East African Rift. My understanding of plate ...
5
votes
3answers
822 views

How can we have “floating” and convection currents in a non-liquid mantle?

I've always thought the earth's layers were as follows: Crust, a few dozen KM think in most places Mantle, completely composed of liquid rock and molten metals, a few thousand KM thick Outer Core, ...
8
votes
2answers
2k views

How viscous is the Earth's mantle?

I'm posting here to get some more expert information based on this question. If the Earth were to stop rotating, removing the centrifugal force causing the equatorial bulge, how long would it take ...
1
vote
1answer
215 views

What is the earth's core temperature?

What is the earth's core temperature and is it really directly related to the earth's mantle?
4
votes
1answer
214 views

Source of sub-surface ringwoodite water

I was reading about the discovery of vast amounts of water locked up in ringwoodite (see here). The authors of the study seem to suggest that previous ideas, involving water deposits being delivered ...
10
votes
3answers
45k views

How is heat transferred from the core through the mantle to the crust?

So, there are three main methods of transferring heat: radiation, convection/mass transfer, and conduction. Presumably radiation is not a major method of heat transport between the core and the crust, ...
6
votes
1answer
2k views

What's the difference between the upper & lower mantle?

Recently I checked a picture about the geologic layers of the Earth, and I saw that the mantle is divided into upper and lower mantle. What's the reason of this differentiation?
6
votes
1answer
192 views

Can the crust be compared to an arch?

Since tectonic plates are held together by lateral stress, friction, and gravity, and the Earth is a sphere, they work just like a full-circle arch or full-sphere dome. So can the crust be compared to ...
4
votes
2answers
125 views

Using current technology, is it possible to directly measure magma flow in the mantle?

Can a device or radioactive tracer be inserted into a volcanic lava lake, sunk to the mantle, and study the flow of magma within the mantle?
8
votes
2answers
204 views

Can volcanos cause isostatic depression

Isostatic depression is normally associated with glaciation, but can other geologic processes result in similar behavior of the lithosphere? Especially, can the weight of a volcano cause the ...
13
votes
1answer
201 views

Is Mars' mantle homogeneous or heterogeneous and what might this say about mantle convection?

A supervisor of mine made an off-hand comment about the fact that Mars used to have plate tectonics, and there is evidence that Mars used to have plate tectonics, however now it does not. The theory ...
11
votes
1answer
483 views

Are mantle plumes distributed around the core randomly or in a known pattern?

Background: The theory of mantle plumes is useful (although controversial) in explaining the occurrence of intra-plate volcanoes. The website here suggests that "hotspots" exist in fixed locations ...