Plate Tectonics: Intraplate Volcanism

Summary

This Earth Science Classroom video delves into plate tectonics, focusing on intraplate volcanism and hotspots. It explains how oceanic crust interacts with magma plumes, which are stationary sources of magma that rise from the core-mantle boundary. As the oceanic plate moves due to convection currents, it carries volcanic islands formed over these plumes. Over time, a linear sequence of volcanoes forms, grows, and eventually moves off the plume, leading to their degradation into seamounts. The video provides a comprehensive look at the creation and destruction of volcanic islands on the ocean floor.

Takeaways

• 🌍 **Plate Tectonics Focus**: The video discusses plate tectonics, specifically intraplate volcanism and hotspots.
• 🔥 **Magma Plume Concept**: It explains magma plumes as areas of magmatic activity that can occur under both oceanic and continental crusts.
• 🌊 **Oceanic Crust Movement**: The video describes how ocean crust moves in conjunction with magma plumes, influenced by convection currents in the asthenosphere.
• 📏 **Crust Thickness**: Oceanic plates are thin, ranging between 5-15 km thick, composed of basaltic rock.
• 🌋 **Volcanism and Magma Plumes**: Volcanoes form on the ocean floor where magma plumes bring magma to the surface.
• 🏔️ **Stationary Magma Plumes**: Magma plumes remain stationary geographically, while the lithospheric plate moves over them.
• 🌄 **Formation of Volcanic Islands**: Volcanoes grow from the ocean floor to become volcanic islands as long as they are positioned above a magma plume.
• 🌉 **Linear Sequence of Volcanoes**: A sequence of volcanoes forms over a magma plume as the plate moves, creating a chain that moves off the plume over time.
• 📉 **Decay of Volcanoes**: As volcanoes move away from the plume, they decrease in size, degrade, and are eroded to form seamounts.
• 🌐 **Convergent Plate Boundaries**: The video concludes by mentioning how volcanoes and plates are destroyed at convergent plate boundaries through subduction or collision.

Q & A

What is the main topic of the video?

The main topic of the video is plate tectonics, specifically focusing on intraplate volcanism and hotspots.

What are hotspots in the context of the video?

Hotspots are areas of magmatic activity and volcanism on the Earth's surface, mostly under oceanic crust on ocean floors but occasionally on continental crust.

What is the composition of the oceanic plate discussed in the video?

The oceanic plate is thin, between 5-15 km thick, and is composed of basaltic rock, which is an extrusive rock made from lava with a density of about 3 g per cubic centimeter.

What role do convection currents in the asthenosphere play in the movement of the plate?

Convection currents in the asthenosphere continuously work to move the plate, influencing the movement of the oceanic crust.

What is a magma plume and how does it relate to the lithospheric plate?

A magma plume is a concentration of hot rock and magma that rises from the core-mantle boundary through the mantle and into the lithosphere. It connects with the lithospheric plate, which is the crust and lithosphere combined.

How does the magma plume's position change relative to the Earth's surface?

The magma plume remains stationary in terms of its geographical location on Earth. It is the plate that moves due to convection currents, while the plume stays in place and continuously supplies magma.

What happens when a volcano is situated above a magma plume?

When a volcano is situated above a magma plume, it can grow as long as there is magma supply from the plume. The volcano will continuously get bigger as magma reaches the Earth's surface.

How are volcanic islands formed in the context of the video?

Volcanic islands are formed when a volcano grows large enough to break the ocean surface, and it is attached to the ocean floor which is in continuous motion due to convection currents.

What is the process that leads to the formation of a linear sequence of volcanoes?

A linear sequence of volcanoes is formed over time as the oceanic plate moves over a stationary magma plume, creating new volcanoes that move off the plume and eventually degrade.

What happens to the volcanoes that move off the magma plume?

Volcanoes that move off the magma plume slowly get smaller and degrade, becoming seamounts as they are eroded and weathered by the elements and the ocean.

What is the ultimate fate of the volcanic islands and seamounts in the video?

The ultimate fate of the volcanic islands and seamounts is that they may eventually meet a convergent plate boundary where subduction or orogeny occurs, leading to the destruction of the volcano and plate.

Outlines

00:00

🌏 Plate Tectonics and Volcanism

This paragraph introduces the topic of plate tectonics with a focus on intraplate volcanism and hotspots. It discusses how magma activity occurs mostly under the oceanic crust but can also be found on continental crust. The video aims to explain the movement of ocean crust in relation to magma plumes, which are areas of intense magmatic activity. The upper mantle and lithospheric plate, which includes both crust and lithosphere, are highlighted as key components. Oceanic plates are described as thin, ranging from 5-15 km thick, and composed of basaltic rock. The role of convection currents in the asthenosphere is emphasized, as they drive the movement of tectonic plates. The central concept of the magma plume, or hotspot, is introduced as a stationary source of magma that rises from the core-mantle boundary and interacts with the lithospheric plate to produce volcanic activity on the ocean floor.

Keywords

💡Plate Tectonics

Plate tectonics is a theory in Earth sciences that describes the movement of Earth's lithosphere, which is divided into several tectonic plates. These plates move over the Earth's surface, interacting with each other at their boundaries. In the video, plate tectonics is central to understanding the movement of the oceanic crust and its interaction with magma plumes, which is key to the formation of hotspots and volcanic activity.

💡Intraplate Volcanism

Intraplate volcanism refers to volcanic activity that occurs within a tectonic plate, rather than at the boundaries where plates interact. This type of volcanism is often associated with hotspots, which are areas of intense magmatic activity that can lead to the formation of volcanoes. The video discusses how intraplate volcanism is driven by magma plumes that rise from deep within the Earth, independent of the movement of tectonic plates.

💡Hotspots

Hotspots are regions of intense volcanic and geothermal activity that are not directly related to the boundaries of tectonic plates. They are typically caused by mantle plumes, which are columns of unusually hot rock that rise from deep within the Earth's mantle. In the video, hotspots are highlighted as areas where magma plumes interact with the Earth's surface, leading to the formation of volcanoes on the ocean floor.

💡Magma Plume

A magma plume is a column of molten rock that rises from deep within the Earth's mantle towards the surface. These plumes are thought to be the source of hotspots and can lead to the formation of volcanoes. The video explains that magma plumes are stationary relative to the Earth's surface, while tectonic plates move over them, leading to the creation of a chain of volcanoes as the plate moves away from the plume.

💡Lithospheric Plate

The lithospheric plate refers to the rigid outer layer of the Earth, which includes both the crust and the uppermost part of the mantle. This plate is thin and made of basaltic rock, which is denser and heavier than the rocks found in continental crust. In the video, the movement of the lithospheric plate over a magma plume is described as a key process in the formation of volcanic islands and chains of seamounts.

💡Oceanic Crust

The oceanic crust is the outermost layer of the Earth's surface beneath the oceans. It is thinner and denser than continental crust, primarily composed of basalt. The video discusses how the oceanic crust moves over magma plumes, leading to the formation of volcanic islands and seamounts as the crust interacts with the stationary hotspots.

💡Convection Currents

Convection currents are the flow of material within a fluid, driven by heat. In the Earth's mantle, these currents are caused by the heating from the Earth's core, which causes solid rock to become less dense and rise, while cooler, denser rock sinks. The video explains that convection currents in the asthenosphere drive the movement of tectonic plates, which in turn affects the location of volcanic activity.

💡Volcanic Island

A volcanic island is a landform that is formed from the eruption of magma through the Earth's surface. These islands are typically found in oceanic settings and are the result of volcanic activity associated with hotspots or tectonic plate boundaries. The video describes how volcanic islands form as a result of magma plumes interacting with the oceanic crust, eventually breaking the surface of the ocean.

💡Seamounts

Seamounts are underwater mountains formed by volcanic activity on the ocean floor. They are often the remnants of extinct volcanoes that have been eroded and subsided below the ocean's surface. In the video, seamounts are mentioned as the end stage of volcanic islands that have moved away from the magma plume and have been eroded and weathered by the ocean.

💡Subduction

Subduction is a geological process in which one tectonic plate moves under another, sinking into the mantle. This process is often associated with the destruction of oceanic crust and can lead to the formation of deep-sea trenches and volcanic arcs. The video briefly mentions subduction as the eventual fate of volcanic islands and seamounts that reach a convergent plate boundary.

Highlights

Introduction to the concept of plate tectonics and its relation to intraplate volcanism.

Exploration of hotspots as areas of magmatic activity and volcanism on Earth's surface.

Discussion on the movement of ocean crust in conjunction with magma plumes.

Description of the upper mantle and lithospheric plate, including their composition and thickness.

Explanation of the composition of oceanic plates and their density.

Role of convection currents in the asthenosphere in moving tectonic plates.

Focus on the magma plume as a stationary source of magma that rises through the mantle.

Magma plumes' interaction with the lithospheric plate and their contribution to volcanic activity.

Stationary nature of magma plumes geographically while the plate moves due to convection currents.

Process of magma reaching the ocean floor and forming volcanoes.

Growth of volcanic islands as a result of continuous magma supply from beneath the ocean surface.

Formation of a volcanic island chain as the oceanic plate moves over a stationary magma plume.

The movement of volcanoes away from the plume and their eventual degradation into seamounts.

Long-term geological process of volcano formation, movement, and destruction at convergent plate boundaries.

Importance of understanding the life cycle of volcanic islands for studying Earth's geological history.

Encouragement for viewers to subscribe and engage with the channel for more Earth science content.

Transcripts

this is the earth science

classroom welcome back to the channel

this is the earth science classroom

we're looking at in this video today

plate tectonics looking at intraplate

volcanism and looking at hotspots so

areas of magmatic activity and volcanism

on the Earth's surface mostly under

oceanic crust on Ocean Floors but

occasionally on continental crust and

this video we're looking at how the

ocean crust is moving in conjunction

with the magma

plume and here we have the upper mantle

and the lithospheric plate which is the

crust and lithosphere combined and this

is an oceanic plate so it's thin between

5 15 km thick it is made or composed of

ptic rock the ous extrusive rock made

from lava which is about three G per C

cubed and we have also the convection

currents in the Asos spere that are

continuously working to move the

[Music]

plate now one of the focus points of

this whole diagram is the magma plume or

the dear which is the balloon or

concentration of hot rock and magma

that's going to rise up from the core

mantle boundary all through the mantle

all through the mesosphere into the

osphere up to and touch in and kind of

connect in with the lithos plate the

oceanic plate and eventually going to

burn through and move the magma up to

the surface of the Earth on the ocean

floor an important part or point to

remember about this diagram with

interplate volcanism is that the magma

plume is going to rise up it's going to

be St stationary it's going to be moving

magma up towards the surface towards the

plate but in terms of location on the

earth it's going to stay in a stationary

position

geographically and relative to the plate

it's going to stay still the Plate's

going to move and be pushed and pulled

by the convection currents but the

actual magnet plume itself is going to

stay exactly where it is and

continuously flow of

magma

this flow of magma is going to reach the

ocean floor the Earth's surface and

produce a volcano on that ocean floor

which will continuously get bigger and

bigger and bigger as long as that

volcano is situated or positioned above

the magma plume which is the source of

magma as long as there magma you can get

a volcano so this volcano is going to

grow until the point where it goes large

enough to to get above the ocean surface

and it becomes a volcanic island so

these little islands are formed through

this process with a magma

plume once the volcano has been

established and formed on this magma

plume it's going to be attached to the

ocean floor which is the plate which is

in continuous motion according to the

contion currents it's going to move move

to One Direction at a certain speed and

then it's going to move off the plume

and a new section of oceanic crust will

be on that plume and it's going to form

a new volcano So eventually over time

you get this sequence this linear

sequence of volcanoes that are formed

over the plume and then move off the

plume and slowly get smaller and small

and smaller and degraded and broken down

and weathered and eroded by the elements

and the ocean to form sea mounts

so these volcanoes become a long

production line of creating these

volcanoes and then move them off the

plume to slowly break down and go back

towards the ocean

floor and eventually go to a point where

it meets a convergent plate boundary and

there's seduction or there's or ogyny

and the volcano and plate gets

[Music]

destroyed

[Music]

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