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.