What Is A Volcanic HOTSPOT?

Summary

This video explores tectonic hot spots and mantle plumes, which are stationary sources of magma deep within Earth's mantle. It explains how these plumes create volcanism, distinct from plate boundary activity, by rising through the mantle and decompressing to form magma. The video discusses famous hotspots like Hawaii and Yellowstone, describing how they form volcanic islands and domes over millions of years, illustrating Earth's dynamic geological processes.

Takeaways

• 🌋 Tectonic hot spots are areas with magma material under the lithospheric plate that is either hotter or less dense, causing it to rise.
• 🔥 A mantle plume, also known as a diapir, is a large volume of magma material that originates from the core-mantle boundary and rises through the mantle due to thermal or compositional differences.
• 📍 Mantle plumes are generally fixed in one geographic location under the plate and can feed magma to the surface for millions of years.
• 🌊 Mantle plumes are more common in oceanic locations due to the thinner crust, which ranges from 7 to 10 miles thick compared to the continental crust that can reach up to 50 miles thick.
• 🏞️ Famous locations of mantle plumes include Hawaii, the Galapagos Islands, Easter Island, Reunion Islands, and Yellowstone in the continental United States.
• 🌏 Mantle plumes can create both oceanic and continental volcanism, with the former being more common due to plate thickness.
• 🌄 Volcanoes formed by mantle plumes can grow into islands, such as the Hawaiian Islands, if they remain over the plume and receive a constant supply of magma.
• 🏔️ As volcanic islands move away from the plume with plate tectonics, they stop being active and eventually erode, becoming seamounts or extinct volcanoes under the sea level.
• 🔄 Mantle plumes are different from plate boundary volcanism, where the latter occurs along the edges of tectonic plates and is associated with three types of plate boundaries: divergent, convergent, and transform.
• ⛰️ Intraplate volcanism, such as that caused by mantle plumes, occurs in the middle of a tectonic plate and is distinct from the volcanism found at plate boundaries.
• 🌐 The study of volcanic island chains and seamounts can provide insights into the history and activity of mantle plumes and the geological processes involved.

Q & A

What is a mantle plume and how is it related to tectonic hotspots?

A mantle plume is a large volume of magma that originates from the core-mantle boundary and rises through the mantle due to differences in thermal properties or composition, causing it to be less dense. It is related to tectonic hotspots as it creates areas of increased volcanic activity where it reaches the lithosphere, forming volcanoes on the surface.

How does a mantle plume create volcanism?

A mantle plume creates volcanism by rising through the mantle and spreading out beneath the lithospheric plate. This process leads to decompression melting, causing more rock to melt due to the decrease in pressure. The magma from the plume then intrudes into the plate, creating volcanoes on the surface.

What is the difference between hotspot volcanism and plate boundary volcanism?

Hotspot volcanism, or intraplate volcanism, occurs in the middle of a tectonic plate and is driven by stationary mantle plumes. Plate boundary volcanism occurs where tectonic plates interact, such as at divergent boundaries where new crust is formed or at convergent boundaries where one plate is subducted beneath another, leading to volcanic activity.

Why are mantle plumes typically fixed in one geographic location?

Mantle plumes are typically fixed in one geographic location because they are anchored at the core-mantle boundary. As tectonic plates move over these stationary plumes, the volcanic activity remains in the same spot relative to the plume, but the location of the volcanic activity on the Earth's surface can change over time.

What is the role of the oceanic plate in the formation of mantle plumes?

The oceanic plate plays a significant role in the formation of mantle plumes because it is generally thinner than the continental crust, ranging from 7 to 10 miles thick. This thinness allows for more occurrences of mantle plumes and the associated volcanic activity in oceanic locations.

How does the thickness of the tectonic plate affect the occurrence of mantle plumes?

The thickness of the tectonic plate affects the occurrence of mantle plumes because thinner plates, like the oceanic plate, offer less resistance to the upward movement of magma from the mantle plume, making it easier for volcanic activity to occur.

What are some examples of locations with mantle plumes?

Examples of locations with mantle plumes include Hawaii, the Galapagos Islands, Easter Island, French Polynesia, Reunion Islands in the Indian Ocean, the Azores in the Atlantic, and Yellowstone in the United States.

How do mantle plumes contribute to the formation of volcanic islands?

Mantle plumes contribute to the formation of volcanic islands by providing a constant flow of magma from deep within the Earth. Over time, this magma accumulates on the ocean floor, forming volcanic seamounts that can eventually rise above sea level to become volcanic islands.

What happens to a volcanic island once it moves away from the mantle plume?

Once a volcanic island moves away from the mantle plume, it no longer receives the constant supply of magma. The volcanic activity ceases, and the island becomes extinct. Over time, it will be eroded by natural forces such as weather, wave action, and exposure to elements, potentially becoming a seamount or subducting if it reaches a plate boundary.

How can the movement of tectonic plates over a mantle plume create a chain of volcanic islands?

As tectonic plates move over a stationary mantle plume, a series of volcanic islands can form in a chain. The islands closest to the plume are active, while those that have moved away become extinct. This creates a sequence of islands of varying ages, reflecting the history of the mantle plume's activity.

What is the significance of the Emperor Seamounts in understanding mantle plumes?

The Emperor Seamounts are a chain of volcanic islands and seamounts in the Pacific Ocean that date back 80 to 100 million years. They provide a geological record of the movement of the Pacific Plate over a mantle plume, illustrating the progression and history of volcanic activity associated with the plume.

Outlines

00:00

🌋 Mantle Plumes and Volcanism

This paragraph introduces the concept of mantle plumes, which are columns of hotter, less dense magma that rise from the core-mantle boundary into the lithosphere, causing decompression melting and creating volcanoes. Mantle plumes are distinct from plate boundary volcanism, as they are fixed in one geographic location and can persist for millions of years, feeding magma to the surface. Examples of locations with mantle plumes include Hawaii, the Galapagos Islands, and Yellowstone. The paragraph also explains the difference between mantle plumes and diapir, emphasizing the thermal and compositional characteristics of mantle plumes.

05:00

🌿 Formation of Volcanic Islands

Paragraph 2 discusses the process by which mantle plumes lead to the formation of volcanic islands. It explains how a fixed mantle plume can feed magma into the crust, creating a volcano on the ocean floor. Over time, this volcano grows as more lava is erupted and solidifies into basaltic rock. Eventually, the island may break the ocean surface, forming a volcanic island. The paragraph also describes how these islands can grow into island chains, such as the Hawaiian Islands, and how they can move away from the plume over time, becoming extinct volcanoes or seamounts. The concept of intraplate volcanism is introduced, contrasting it with the more common plate boundary volcanism.

10:01

🏞️ Plate Tectonics and Volcanism

The final paragraph contrasts interplate volcanism, which is associated with mantle plumes, with the volcanism that occurs at plate boundaries. It explains that while mantle plumes are stationary and create specific volcanic features like domes or islands, plate boundary volcanism is characterized by chains of volcanoes along divergent and convergent boundaries. The paragraph highlights the differences in the location and movement of volcanic activity between these two types of volcanism, emphasizing the unique characteristics of mantle plumes and their role in creating distinct geological features.

Keywords

💡Mantle Plume

A mantle plume is a large volume of magma originating from deep within the Earth, at or near the core-mantle boundary. It is characterized by its hotter than usual temperature or its less dense composition, allowing it to rise through the mantle. In the context of the video, mantle plumes are responsible for creating hotspot volcanism, which is not directly associated with plate boundaries. An example from the script is the Hawaiian Islands, which are formed due to a mantle plume that has been active for millions of years.

💡Volcanism

Volcanism refers to the geological process of magma reaching the Earth's surface, resulting in the formation of volcanoes and the release of gases. The video discusses two types of volcanism: hotspot volcanism caused by mantle plumes and plate boundary volcanism. The script uses volcanism to explain how mantle plumes create surface features like the Hawaiian Islands and Yellowstone.

💡Lithospheric Plate

The lithospheric plate is the rigid outermost layer of the Earth, comprising the crust and the upper part of the mantle. In the script, it is mentioned that mantle plumes create volcanism by spreading magma under the lithospheric plate, leading to the formation of volcanoes at the surface.

💡Decompression Melting

Decompression melting occurs when rising magma experiences a decrease in pressure, causing the solid rock around it to melt. The script explains that as the mantle plume's magma rises towards the lithospheric plate, decompression melting occurs, contributing to the formation of more magma and the creation of volcanoes.

💡Mesosphere

The mesosphere is a layer of the Earth's mantle located between the lower mantle and the asthenosphere. The script describes how mantle plumes rise through the mesosphere, part of their journey from the core-mantle boundary towards the surface.

💡Convection Currents

Convection currents are the movement of material within a fluid or gas due to differences in temperature and density. In the Earth's mantle, these currents help to transport the magma from mantle plumes towards the lithospheric plate, as mentioned in the script.

💡Oceanic Plate

An oceanic plate is a tectonic plate composed of the Earth's oceanic lithosphere, which is thinner and denser than continental crust. The script notes that oceanic plates are more prone to the formation of mantle plumes and associated volcanism due to their thinner nature, as seen in locations like Hawaii and the Galapagos Islands.

💡Continental Crust

The continental crust is the Earth's outermost solid layer beneath the continents, which is thicker and less dense than oceanic crust. The script contrasts the continental crust with the oceanic plate, explaining that the thicker continental crust is less likely to have mantle plumes, although examples like Yellowstone are mentioned.

💡Afar Triple Junction

The Afar Triple Junction is a geological feature in East Africa where three tectonic plates meet. The script uses this as an example of how mantle plumes can push up under the crust, causing elevated areas like the Ethiopian Dome and the Kenyan Dome.

💡Seamount

A seamount is an underwater mountain formed by volcanic activity. In the script, seamounts are mentioned as the result of volcanic islands that have moved away from the active mantle plume and are no longer receiving magma, eventually eroding and sinking below sea level.

💡Intraplate Volcanism

Intraplate volcanism refers to volcanic activity that occurs within a tectonic plate, rather than at the boundaries between plates. The script explains that mantle plumes are a form of intraplate volcanism, as they are stationary and can cause volcanic activity in the middle of a plate, such as in Yellowstone or the Hawaiian Islands.

Highlights

Tectonic hot spots are locations with hotter magma material beneath the lithospheric plate.

A mantle plume is a large volume of magma that rises from the core-mantle boundary due to thermal and compositional differences.

Mantle plumes create decompression melting as they rise, causing surrounding rock to melt.

Mantle plumes have a tail and a connected pipe of magma that extends from the core-mantle boundary to the surface.

Mantle plumes are generally fixed in one geographic location under the plate.

Mantle plumes can feed volcanism for millions of years in specific locations.

Mantle plumes are found in both oceanic and continental locations, with a higher occurrence in thinner oceanic plates.

Examples of mantle plume locations include Hawaii, the Galapagos Islands, and Yellowstone.

Mantle plumes can create volcanic islands as they feed magma to the crust.

Volcanic islands grow over time as more lava forms into igneous rock.

As tectonic plates move, volcanic islands can become inactive and erode into seamounts.

The Hawaiian Islands and Emperor Seamounts showcase a chain of islands formed by a mantle plume.

Mantle plumes are stationary and different from plate boundary volcanism, which occurs along plate edges.

Intraplate volcanism, caused by mantle plumes, occurs in the middle of a plate, unlike plate boundary volcanism.

Mantle plumes can create domes or calderas, as seen in Africa and Yellowstone.

Key terms related to mantle plumes include magma, decompression melting, and lithospheric plate interaction.

Transcripts

foreign

this is the earth science classroom

welcome back to the channel so this

video is in the playlist for both

tectonics and volcanoes and looking at

tectonic hot spots which is some

locations around the world that have

hotter magma material right under the

lithospheric plate and this video is

going to discuss what is a mantle plume

where do these metal plumes occur on the

earth and how a mantle plume creates

volcanism and finally how this hot spot

volcanism or interplate volcanism is

different to volcanoes that form on a

plate boundary whether you have a

convergent plate boundary and one plate

is subducting

so geologically a mantle plume oil magma

plumer is occasionally known as is a

form of diaper now diaper is a large

amount or large volume of magnetic

material that is either

different to the Australian rock through

thermal properties being hotter or

through the composition where it's just

less dense and can rise based on density

so this large amount of generally magma

this large volume of magma is under the

surface generally at the core mantle

boundary heated by the insane heat from

the core the outer core and send in

large volumes of magnetic material

to rise up through the lower mantle or

mesosphere into the acetosphere or the

upper mantle and go through the

convection currents and on its way

towards the lithospheric plate which is

the lithosphere and the crust towards

the surface and that also create

decompression melting which would cause

more of the rock around it to melt as it

goes into an area of less pressure so

the liquid has an area to move now this

diaper or plume has a tail and a

connected pipe or continued volume of

magma that is coming from the core

mantle boundary up through the mantle

and the layers out towards the surface

and it's connected and at the head or

top of the deer Pier or plume you're

going to have this spreading out effect

of the magma right underneath the

lithospheric plate and send in magma

into the plate and creating volcanoes on

the surface

now these mantle plumes are special

because they are generally fixed in one

geographic location under the plate

around the world and these may stay for

an extended period of time so this

mantle plume could be feeding hot fluid

magma basaltic magma and mafic magma

from deep down in the lower mantle up

towards the surface in a certain

location around the world for in excess

of hundreds of thousands if not hundreds

of millions of years and feeding this

volcanism on the surface from this

mantle plume just below the plate so

locations around the world are both

found in Oceanic locations and on

continents and mostly Oceanic because

the oceanic plate is generally thinner

even though it's dense made up of salt

it's generally thinner between 7 and 10

miles thick compared to the continental

crust which could be in some areas of

rogeny belts or Mountain belts could be

as as 50 miles

So based on the plate thickness the

oceanic plate and the oceans around the

world have more occurrence of these

mantle plumes and the volcanism

occurring so areas like the Southern

Pacific South Pacific Northern Pacific

areas like Hawaii the Galapagos Islands

Easter Island and various areas around

French Polynesia they look at the Indian

Ocean and reunion islands and the

Atlantic with the Azores or Azores or on

the continents you have areas like

Yellowstone which is a classic National

Park in the US but also is a location of

a massive mantle plume that has moved

great distances since its formation or

Discovery millions of years ago and the

other locations famous is in Africa on

the African continental plate with the

afar Junction triple Junction caused by

two large domes where the Magna plume is

pushing up under the crust pushing

across higher elevation and causing

these two domes the Ethiopian Dome and

the king and Dome you can check more

about those domes on my East African

Rift videos

[Music]

at some points around the world as I

discussed like Hawaii and the Galapagos

you have this fixed mantle plume feeding

hot magmac material which is mafic in

composition that is basaltic magma and

it's feeding into the play into the

crust and flowing onto the ocean floor

and providing the ocean floor with this

constant flow of of magma and lava turn

into basaltic igneous rock and forming a

volcano on the ocean floor now over time

that volcano is going to grow and

develop as more and more lava comes out

and forms into igneous rock and it grows

eventually it's going to reach the top

of the ocean surface and go above the

ocean's surface and become a volcanic

island this island is going to grow as

long as it's on top of the mantle plume

being fed this constant magma and over

the course of thousands of years the

volcano Island's going to grow and grow

into a large island series like the

Hawaiian Islands or the Galapagos

Islands or the Azores in Atlantic and

the island that's on top of the plume is

going to grow and develop and as it

moves with the tectonic plate in the

direction of the convection currents by

the Pacific Oceans moving certain

direction according to the oceanic crust

then that island that volcanic island

will no longer be active and just become

an island and it'll move off the plume

and it will just start to exist as an

island but slowly break down due to the

forces of weather and erosion out in the

exposure to the elements over a long

period of time and the wave action and

that Island's going to start to break

down and that solid

saltic rock is going to break down and

that Island's going to get smaller and

smaller and smaller until it eventually

gets under the sea level under the ocean

and become what we call a seamount so an

extinct volcano a seamount and it's you

get small and small and smaller and you

can see it through sonar and radar and

satellites but you see this long chain a

long sequence of

currently active volcanoes over the

plume and then a long sequence of chain

of increasingly older islands and

extinct volcanoes that have been moved

by the plate motion and a long sequence

of these Island chains that you can see

now the classic one is the Hawaiian

islands and the emperor sea mounts here

is thousands of miles long chain of

islands dating back 80 to 100 million

years and you see where some of the

islands have actually been subducted at

the edge of the Pacific Ocean where it's

going to descend underneath the carnival

crust of the Eurasian plate or the the

North American plates but in particular

the Eurasian plate and be partially

melted back into magma that's going to

erupt through a continental volcanic

chain or volcanic Arc and the cycle of

the rock cycle is going to continue but

these amazing Islands in this long chain

of sequence

based on age and how fast it's moving

off the plume and the current active

volcanoes on the plume are a fantastic

way to see the progression and the

history of this area and of the mantle

plume how long it's been there how

active it is and how much it produces to

create these large volcanic islands

so a mantle plume an intraplate

volcanism intra means in the middle or

inside so in the middle of this massive

Atomic plate you have volcanism and it's

different to the volcanism that occurs

on the plate boundary now plates

boundaries come in three types we know

Divergent where you have the mid-ocean

ridge or Rift Valley and you have

convergent plate boundaries where you

have two plates converging towards each

other and you have subduction based on

density differences of each plate and

you also have transform where they slide

past each other now volcanism generally

occurs with divergent plate boundary

where you have the lava coming out the

ridge the ocean ridge that has found in

63 and you also have volcanism that

happens where one plate the denser plate

is going to subduct under the subduction

or subducting slab will partially melt

due to friction and temperature

increases back down towards the

asthenosphere and you'd have partial

melting of this starting to subduct him

play but mostly the melting of the plate

that's going to float on top generally

is going to be that lighter Dent lighter

less dense

plate which is going to be Continental

or sometimes Oceanic and that's going to

create magma it's going to rise up on

the edge or

coastlines of these plates and form

either volcanic island chains on the

boundary of the two plates a certain

distance away from the subduction zone

or more commonly like the ring of fire

on the edge of continental plates where

you have this long chain or Arc of

volcanoes that are actually a certain

distance and parallel to the coastline

which is showing you where the

subduction zones are located and the

trenches so it's different because this

mantle plume is a certain location and

it's fixed whereas the plate boundaries

and subduction you have this long chain

that is the volcanoes are usually fixed

in location whereas the mantle plume the

volcanoes can move with the plate but

the actual magma is in the same location

so there's some differences between the

interplate volcanism and the volcanism

you get with plate boundaries

so in conclusion a interplate volcanism

or a mantle plume is a stationary plume

of magma rising up from the core mantle

boundary rising up through the mantle

into the upper mantle and reaches the

plate spreads out and pours Mythic

basaltic magma into that lithospheric

plate creating volcanoes on the surface

with this ocean floor or vacant Islands

or pushing up the

ground the surface of the Earth into a

dome where the magma pushes up and it's

going to increase the elevation of the

above crust and cause domes like in

Africa or volcanism like you see in

Yellowstone with the geysers and the

flow of magma

under the National Park to create a

Caldera volcano so there are certain key

terms we know with plumes it is that

long tailed magmatic material rising up

and creating volcanism on the surface

[Music]

thank you