Peridotite

Definition

Peridotite is a dense, coarse-grained igneous rock primarily composed of olivine, along with lesser amounts of pyroxene and other minerals. It is the dominant rock type found in the Earth's upper mantle, playing a crucial role in understanding Earth's internal structure and composition due to its connection to mantle processes and the formation of the crust.

5 Must Know Facts For Your Next Test

1. Peridotite makes up about 90% of the Earth's upper mantle and is crucial for understanding tectonic processes.
2. The high olivine content gives peridotite its characteristic green color, which can be observed in some exposed formations.
3. Peridotite can be brought to the surface through tectonic processes, providing valuable insight into mantle dynamics.
4. It plays a significant role in the generation of basaltic magma when subjected to high temperatures and pressures, leading to volcanic activity.
5. Peridotite is often studied in the context of plate tectonics, as it helps explain the interactions between the Earth's lithosphere and asthenosphere.

Review Questions

• How does peridotite contribute to our understanding of the Earth's upper mantle and its processes?
  • Peridotite, being the primary rock type of the Earth's upper mantle, offers essential insights into the composition and behavior of this layer. Its high olivine content indicates the mineralogical characteristics of the mantle and helps geologists understand temperature and pressure conditions at depth. By studying peridotite, researchers can gain knowledge about mantle convection, plate tectonics, and even how magma is generated beneath tectonic plates.
• Discuss the significance of peridotite in volcanic activity and how it relates to mantle dynamics.
  • Peridotite is significant in volcanic activity as it can partially melt under certain conditions to generate basaltic magma. This process occurs in regions where mantle material rises due to tectonic forces or mantle plumes. The melting of peridotite not only contributes to volcanic eruptions but also provides clues about the thermal state and dynamics of the Earth's upper mantle, highlighting how deep Earth processes can impact surface phenomena.
• Evaluate the implications of peridotite's composition for understanding tectonic plate interactions.
  • The composition of peridotite has profound implications for understanding tectonic plate interactions. As a major component of the upper mantle, its presence influences how plates behave during subduction or rifting. When plates collide, peridotite may be subjected to extreme pressure and temperature conditions, leading to metamorphism or partial melting. This interaction helps explain geological features such as mountain ranges and volcanic arcs, showcasing how deep Earth materials shape surface geology.

Related terms

Olivine: A magnesium iron silicate mineral that is a primary component of peridotite and is significant for understanding mantle composition.

Asthenosphere: The semi-fluid layer of the Earth's upper mantle that lies beneath the lithosphere, where peridotite may partially melt to produce magma.

Mantle Plume: A column of hot, solid material that rises through the mantle, potentially causing melting of peridotite and leading to volcanic activity.