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2021-06-17

What causes convection currents in the asthenosphere?

What causes convection currents in the asthenosphere?

The plastic movement of the mantle material moves like the flow of mountain glaciers, carrying the lithospheric plates along as the convection movement in the mantle moves the asthenosphere. The increased density accelerates the lithospheric plate toward the subduction zone.

What is the result of convection currents in the mantle?

Convection currents play a role in the circulation of fluids. Convection currents are the result of differential heating. Inside Earth, the convection of mantle material is thought to cause the movement of the overriding crustal plates, resulting in events such as earthquakes and volcanic eruptions.

What role does mantle convection play in plate tectonics?

How does mantle convection drive plate tectonics? As mantle convection rises, it breaks apart the Earth to form mid-oceanic ridges (tensional force). When it sinks down, it breaks it apart (compressional force). These tensional and compressional forces are what drives plate tectonics.

What is the original heat source for the mantle?

Radioactive potassium, uranium and thorium are thought to be the three main sources of heat in the Earth’s interior, aside from that generated by the formation of the planet. Together, the heat keeps the mantle actively churning and the core generating a protective magnetic field.

What is the average rate of temperature increase in the mantle?

As a general rule, the crust temperature is rising with depth due to the heat flow from the much hotter mantle; away from tectonic plate boundaries, temperature rises in about 25–30 °C/km (72–87 °F/mi) of depth near the surface in most of the world.

Which rock type makes up most of the mantle?

The rocks that make up Earth’s mantle are mostly silicates—a wide variety of compounds that share a silicon and oxygen structure. Common silicates found in the mantle include olivine, garnet, and pyroxene. The other major type of rock found in the mantle is magnesium oxide.

What is the major source of Earth’s heat?

There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet been lost; (2) frictional heating, caused by denser core material sinking to the center of the planet; and (3) heat from the decay of radioactive elements.

How far into the earth have we gone?

Humans have drilled over 12 kilometers (7.67 miles) in the Sakhalin-I. In terms of depth below the surface, the Kola Superdeep Borehole SG-3 retains the world record at 12,262 metres (40,230 ft) in 1989 and still is the deepest artificial point on Earth.

What is the deepest hole dug on earth?

Kola Superdeep Borehole

How much does temperature increase with depth?

The geothermal gradient (i.e. the increase in temperature with an increase in depth in the Earth) is not equal all over the world. On average, the temperature increases 2°- 3° C per 100 m in depth, however the increase can range from 1° to 5° C/100 m.

Why does temperature increase with depth?

At depth, some of the heat comes from the cooling of the Earth’s core, but most is from decay of radioactive elements, mainly uranium, thorium and potassium, in rocks of the crust. This means that the geothermal gradient (the increase in temperature with depth) varies with the chemical composition and age of the rocks.

What causes convection currents in the asthenosphere?

The plastic movement of the mantle material moves like the flow of mountain glaciers, carrying the lithospheric plates along as the convection movement in the mantle moves the asthenosphere. The increased density accelerates the lithospheric plate toward the subduction zone.

What is the result of convection currents in the mantle?

Convection currents play a role in the circulation of fluids. Convection currents are the result of differential heating. Inside Earth, the convection of mantle material is thought to cause the movement of the overriding crustal plates, resulting in events such as earthquakes and volcanic eruptions.

Which processes are caused by convection currents in the mantle?

Mantle convection causes tectonic plates to move around the Earth’s surface. It seems to have been much more active during the Hadean period, resulting in gravitational sorting of heavier molten iron, nickel, and sulphides to the core and lighter silicate minerals to the mantle.

How do we know there is convection in the mantle?

The mantle is heated from below (the core), and in areas that are hotter it rises upwards (it is buoyant), whereas in areas that are cooler it sink down. This results in convection cells in the mantle, and produces horizontal motion of mantle material close to the Earth surface.

What is the evidence for mantle convection and what is the mechanism that causes it?

It has long been known that throughout the mantle there are convection currents circulating, caused by the difference in temperature at the earth’s interior and surface. Hot material from the earth’s outer core rises very slowly (over millions of years) throughout the mantle.

What is the heat source for convection in the mantle?

The primary sources of thermal energy for mantle convection are three: (1) internal heating due to the decay of the radioactive isotopes of uranium, thorium, and potassium; (2) the long-term secular cooling of the earth; and (3) heat from the core.

Where does the heat come from that drives this convection current in mantle?

Question One: Where does the heat come from that drives this convection current in the mantle? The heat driving the convection current in the mantle comes from the extreme temperature in the earth’s core, and the heat from the mantle itself.

How mantle convection affects the movement of plates?

Geologists have hypothesized that the movement of tectonic plates is related to convection currents in the earth’s mantle. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth’s crust.

Why is the lower mantle not considered part of the lithosphere?

Geologists do not agree about the structure of the lower mantle. Some geologists think that subducted slabs of lithosphere have settled there. Other geologists think that the lower mantle is entirely unmoving and does not even transfer heat by convection.

What is the main difference between the two layers of the mantle?

There are very small differences between the two layers. The upper mantle has Olivine (a very special rock), compounds with silicon dioxide, and a substance called Peridotite. The lower mantle is more solid than the upper mantle.

What is the difference between upper and lower mantle?

The first difference between the upper mantle and lower mantle is their location. The upper mantle adjoins the crust to form the lithosphere, whereas the lower mantle never comes in contact with the crust.

Does the lower mantle move?

The lower mantle is solid rock. The upper mantle is also solid rock, but it has a thin outer layer that is part liquid. This liquid layer moves very slowly. This causes Earth’s surface to change and move, but it moves much too slowly for us to feel it.

What is important about the lower mantle?

Importance of the Lower Mantle The lower mantle is an important player in the geological action we see above the surface, such as earthquakes and volcanoes. The core heats the lower mantle, and the warm lava rises into the upper mantle.

What is the lowest part of the mantle?

asthenosphere

Is the asthenosphere the lower mantle?

Asthenosphere: lower mantle, composed of “plastic solid” akin to playdoh. Outer core: liquid. Inner core: solid.

Is the asthenosphere solid?

The asthenosphere is a solid but it can flow, like toothpaste. The lithosphere rests on the asthenosphere.

Why is upper mantle called asthenosphere?

The upper mantle is called asthenosphere, “astheno” is a Greek word meaning ‘weak’. It is called weak layer because it is in liquid state where rock material deforms more readily, and magma formation takes place.

Is the asthenosphere the same as the upper mantle?

The asthenosphere is a part of the upper mantle just below the lithosphere that is involved in plate tectonic movement and isostatic adjustments. The upper part of the asthenosphere is believed to be the zone upon which the great rigid and brittle lithospheric plates of the Earth’s crust move about.

Why are rocks in the asthenosphere easily deformed?

Because the lithosphere is floating in the asthenosphere which is more ductile than the brittle lithosphere, the soft asthenosphere can flow to compensate for any change in thickness of the crust caused by erosion or deformation.

What is a fact about asthenosphere?

The asthenosphere is the region of the upper earth considered to be mechanically weak. It sits below the lithosphere, reaching from 50 miles to 120 miles below the earth’s surface. The pressure in the asthenosphere is so great that rocks are able to flow as if they were liquid. …

Why is the asthenosphere unique?

The asthenosphere is a soft and fluid layer responsible for driving plate tectonics motion. Earth’s crust (lithosphere) is like a hard, rigid shell and sits on top of the asthenosphere. Then, it rides it like a conveyor belt transporting it slowly from one place to another.

Why is the asthenosphere important?

The asthenosphere is now thought to play a critical role in the movement of plates across the face of Earth’s surface. Some observers have described the asthenosphere as the ‘lubricating oil’ that permits the movement of plates in the lithosphere. …

How thick is the asthenosphere in miles?

The relatively plastic layer of the upper mantle of the Earth on which the tectonic plates of the lithosphere move. The asthenosphere is approximately 200 km [124 miles] thick and, owing to its depth below the Earth’s surface, warm (~ 1,400 degC [2,640 degF]) but not molten.

How hot is the asthenosphere?

2,372°F.

What will happen if there is no convection current in the asthenosphere?

If for some reason convection stopped, air would not circulate, and weather would stop. Air wouldn’t flow over the waters, suck up moisture and then rain it out on land. Without this rain, all plants and crops would die.

What is the asthenosphere made of?

The asthenosphere is also known as the “low velocity” zone of the mantle because seismic waves slow down as they pass through it. This property tells us that the asthenosphere is composed of partially molten rock slushlike material consisting of solid particles with liquid occupying spaces in between.