Mantle plumes

Definition

Mantle plumes are upwellings of abnormally hot rock within the Earth's mantle that can lead to volcanic activity when they reach the lithosphere. These plumes are thought to be responsible for forming hotspots, where magma from deep within the Earth rises and creates volcanic islands and large igneous provinces. Understanding mantle plumes is crucial for comprehending magma composition and properties, as they influence the temperature, pressure, and mineral content of the resulting magma.

5 Must Know Facts For Your Next Test

1. Mantle plumes originate at the boundary between the Earth's core and mantle, where heat is transferred from the core to the mantle.
2. As mantle plumes rise, they can create pressure changes that result in melting rocks, generating magma with distinct chemical compositions.
3. The volcanism associated with mantle plumes can lead to the formation of large igneous provinces, such as the Columbia River Basalt Group in the United States.
4. Unlike tectonic plate boundaries, which are associated with specific types of eruptions, hotspot volcanism from mantle plumes can produce a wide variety of magma types, including basaltic and rhyolitic compositions.
5. The study of mantle plumes has implications for understanding plate tectonics and the thermal evolution of the Earth over geological time scales.

Review Questions

• How do mantle plumes affect magma composition and properties when they rise to the lithosphere?
  • When mantle plumes rise towards the lithosphere, they bring abnormally hot rock that can melt surrounding materials, leading to the formation of magma with varying chemical compositions. The temperature and pressure conditions during this process influence the types of minerals that crystallize as the magma cools. Consequently, this interaction between mantle plumes and surrounding rocks can result in diverse magma types, such as basalt or rhyolite, each with distinct properties.
• Discuss the differences in volcanic activity associated with mantle plumes compared to tectonic plate boundaries.
  • Volcanic activity linked to mantle plumes often results in hotspots that generate isolated volcanic features like islands, such as Hawaii. In contrast, volcanic activity at tectonic plate boundaries usually involves more predictable eruptions tied to subduction or rifting processes. While mantle plume activity can produce a variety of magma types due to its influence on surrounding materials, tectonic boundaries tend to favor specific volcanic rock formations based on their geologic context.
• Evaluate how studying mantle plumes can enhance our understanding of Earth's thermal evolution and plate tectonics.
  • Researching mantle plumes provides valuable insights into Earth's internal processes and thermal dynamics. By examining how these hot upwellings influence volcanic activity and magma generation, scientists can better understand the heat transfer mechanisms within Earth's interior. Additionally, studying the relationship between mantle plumes and plate tectonics helps explain how large igneous provinces form and evolve over geological time, contributing to our knowledge of Earth’s history and geological transformations.

Related terms

hotspots: Locations on the Earth's surface that experience volcanic activity due to mantle plumes, often resulting in the formation of islands or large volcanic structures.

magma:

Molten rock located beneath the Earth's surface, which can rise through cracks and fissures to create lava during a volcanic eruption.

igneous rocks: Rocks formed from the cooling and solidification of magma or lava, which can provide insights into the composition and properties of magma generated by mantle plumes.