Fractional crystallization

Definition

Fractional crystallization is a process in which different minerals crystallize from a cooling magma at different temperatures, leading to the separation of various components within the melt. This process is crucial in understanding how diverse igneous rocks are formed from a single magma source, revealing insights into both magma composition and the formation of intrusive igneous features.

5 Must Know Facts For Your Next Test

1. Fractional crystallization can lead to the formation of different types of igneous rocks from the same initial magma source by altering its mineral composition as it cools.
2. As certain minerals crystallize out of the magma, they remove elements from the liquid, which changes the chemical composition of the remaining melt.
3. This process is often seen in large plutons where initial crystallization leads to more silica-rich residual magma, resulting in granite formation.
4. Fractional crystallization explains why certain minerals are found together in specific igneous rock formations and helps geologists predict mineral deposits.
5. The process significantly contributes to understanding volcanic activity and the evolution of magmas, influencing the types of eruptions that may occur.

Review Questions

• How does fractional crystallization influence the mineral composition of igneous rocks formed from a single magma source?
  • Fractional crystallization affects the mineral composition by causing different minerals to crystallize out at varying temperatures. As certain minerals solidify and separate from the remaining melt, the elements in those minerals are removed from the magma. This alteration in composition can lead to distinct rock types, such as basalt or granite, even when originating from the same magma source, showcasing how temperature and cooling rates dictate rock diversity.
• Discuss how Bowen's Reaction Series relates to fractional crystallization and its implications for understanding intrusive igneous features.
  • Bowen's Reaction Series provides a framework for understanding fractional crystallization by outlining the sequence in which minerals crystallize from cooling magma. This series shows that as temperature decreases, specific minerals form and solidify at different stages. This is crucial for recognizing intrusive igneous features because it explains how a pluton can evolve into complex compositions, leading to various textures and mineral arrangements within granite or diorite.
• Evaluate the role of fractional crystallization in predicting volcanic behavior and potential mineral deposits associated with igneous processes.
  • Fractional crystallization plays a significant role in predicting volcanic behavior by indicating how magmas evolve over time as they cool and crystalize. As certain minerals are removed, the residual melt becomes enriched in other elements, which can lead to specific types of eruptions and volcanic rock formations. Additionally, understanding this process helps geologists identify potential mineral deposits associated with volcanic activity, as it reveals where certain minerals might concentrate based on their crystallization temperature and composition during magma evolution.

Related terms

Magma: Magma is molten rock located beneath the Earth's surface that can crystallize to form igneous rocks upon cooling.

Bowen's Reaction Series:

Bowen's Reaction Series illustrates the order in which different minerals crystallize from cooling magma, demonstrating how temperature affects mineral formation.

Igneous rock: Igneous rock is formed through the solidification of molten material, either from lava at the surface or magma beneath the Earth's crust.