Peridotite

Definition

Peridotite is a dense, coarse-grained igneous rock primarily composed of olivine and is commonly found in the Earth's upper mantle. It serves as the main source of magnesium and iron in the mantle and plays a vital role in understanding the composition and behavior of the mantle during geological processes such as plate tectonics and volcanic activity.

5 Must Know Facts For Your Next Test

1. Peridotite is mostly found beneath continental crust and is significant in understanding the Earth's mantle composition.
2. It typically contains around 70% olivine, with other minerals like pyroxene and garnet present in smaller amounts.
3. This rock type is essential for studying the processes that occur in the mantle, including convection and melting.
4. Peridotite can be brought to the surface through volcanic eruptions, particularly in regions with oceanic crust or rift zones.
5. The study of peridotite contributes to our understanding of plate tectonics, as it helps explain how materials are cycled within the Earth.

Review Questions

• How does peridotite's composition relate to its role in the Earth's upper mantle?
  • Peridotite's composition, primarily made up of olivine along with pyroxene and garnet, directly influences its density and physical properties. This makes it a significant rock type in the upper mantle, where it provides insights into the geochemical processes that shape our planet. Understanding peridotite helps geologists piece together how the mantle behaves under different conditions, particularly during tectonic activity.
• Discuss the significance of peridotite in understanding mantle convection and its impact on plate tectonics.
  • Peridotite plays a crucial role in understanding mantle convection because its mineral composition impacts its melting point and viscosity. This affects how heat is transferred within the Earth, driving the movement of tectonic plates. The study of peridotite also sheds light on how material is recycled between the surface and the mantle, influencing geological features like mountain ranges and ocean basins.
• Evaluate how studying peridotite can enhance our knowledge of volcanic activity and its relationship to mantle dynamics.
  • Studying peridotite enhances our knowledge of volcanic activity by revealing how this rock type can ascend through the mantle to reach the surface during eruptions. The melting of peridotite due to pressure changes or temperature increases generates magma, which feeds into volcanic systems. By analyzing how peridotite behaves under various conditions, scientists can better predict volcanic eruptions and understand their connection to broader mantle dynamics and tectonic movements.

Related terms

Olivine:

A greenish mineral that is a primary component of peridotite, consisting mainly of magnesium iron silicate.

Asthenosphere: The semi-fluid layer of the upper mantle located beneath the lithosphere, which allows for the movement of tectonic plates.

Mantle Plume: A localized column of hot magma rising from deep within the mantle, which can cause volcanic activity when it reaches the surface.