Pluton

Definition

A pluton is a large, intrusive igneous rock body that forms from the cooling and solidification of magma beneath the Earth's surface. These formations can vary in size and shape, and they contribute significantly to the geological features of an area, often leading to the creation of mountain ranges and other landforms. Plutons are primarily classified based on their size and relationship to surrounding rock, which helps in understanding the geological history and processes involved in their formation.

5 Must Know Facts For Your Next Test

1. Plutons can be formed from different types of magma, including granitic and dioritic compositions, leading to various mineral content and textures.
2. As plutons cool slowly underground, they tend to develop coarse-grained textures with visible crystals, contrasting with volcanic rocks that cool quickly on the surface.
3. Many mountains around the world, such as the Sierra Nevada in California, are composed largely of exposed plutons that have been brought to the surface through erosion.
4. The study of plutons provides insights into tectonic processes, as their formation is often related to subduction zones or continental collisions.
5. Plutons can influence local geology by altering surrounding rocks through processes like metamorphism due to their heat and mineral composition.

Review Questions

• How do plutons contribute to the geological landscape and what features do they help create?
  • Plutons play a significant role in shaping the geological landscape by contributing to the formation of mountain ranges and other landforms. As these large bodies of igneous rock cool and solidify beneath the Earth's surface, they can exert pressure on surrounding rocks, leading to uplift and deformation. Over time, erosion may expose these plutons, creating prominent geological features that can dominate the local topography.
• Compare and contrast batholiths and stocks as types of plutons in terms of their size and formation.
  • Batholiths and stocks are both types of plutons characterized by their formation from solidified magma, but they differ significantly in size. Batholiths are massive plutons that cover an area greater than 100 square kilometers, often comprising multiple intrusions. In contrast, stocks are smaller plutons, typically less than 100 square kilometers. Both share similar origins related to tectonic processes but differ mainly in their scale and impact on the surrounding landscape.
• Evaluate the importance of studying plutons for understanding Earth's tectonic processes and geological history.
  • Studying plutons is crucial for gaining insights into Earth's tectonic processes and geological history because they serve as indicators of past magmatic activity related to plate tectonics. By analyzing their composition, size, and relationship with surrounding rocks, geologists can infer information about ancient subduction zones or continental collisions. This knowledge not only enhances our understanding of geological evolution but also aids in predicting future geological events related to tectonic movements.

Related terms

Intrusive Igneous Rock: Rock formed from the solidification of magma that cools slowly beneath the Earth's surface, resulting in larger crystals.

Batholith: A massive, deep-seated pluton that covers an area greater than 100 square kilometers and is often formed from multiple intrusions of magma.

Stock: A smaller pluton, typically less than 100 square kilometers in area, that often has a similar origin to batholiths but is more limited in extent.