Fractional crystallization

Definition

Fractional crystallization is a process where different minerals crystallize from magma at different temperatures, leading to the separation of solid minerals from the liquid phase. This method is crucial in understanding how the composition of magma changes over time as it cools and differentiates, ultimately influencing the types of rocks that form. By analyzing this process, one can gain insights into magma properties and the evolutionary paths of magmas as they undergo differentiation.

5 Must Know Facts For Your Next Test

1. As magma cools, different minerals crystallize at specific temperature ranges due to variations in their melting points, allowing for a sequence of mineral formation.
2. Bowen's Reaction Series illustrates the order in which minerals crystallize from magma, highlighting how fractional crystallization influences mineral composition in igneous rocks.
3. Fractional crystallization can lead to the formation of diverse rock types, such as basalt and granite, depending on which minerals are removed from the melt.
4. This process not only affects the physical and chemical properties of the remaining liquid magma but also plays a significant role in the development of mineral deposits.
5. In nature, fractional crystallization is often observed in layered intrusions and volcanic systems, showcasing how complex and varied igneous rocks can be.

Review Questions

• How does fractional crystallization contribute to the diversity of igneous rock types?
  • Fractional crystallization leads to the diversity of igneous rock types by allowing different minerals to crystallize out of a cooling magma at varying temperatures. This sequential crystallization results in the removal of specific minerals from the liquid phase, altering the composition of the remaining melt. Consequently, this change in composition influences the final rock type formed, whether it's a basalt or granite, as well as the texture and mineralogy present in those rocks.
• Discuss how Bowen's Reaction Series relates to fractional crystallization and its impact on magma evolution.
  • Bowen's Reaction Series provides a framework for understanding the order of mineral crystallization from cooling magma and is closely tied to fractional crystallization. As minerals crystallize at specific temperatures outlined in the series, each mineral's removal from the liquid alters its composition, leading to magmatic differentiation. This means that as some minerals solidify, they deplete certain elements from the remaining melt, resulting in a more evolved magma with different characteristics, which can eventually produce various rock types.
• Evaluate the significance of fractional crystallization in relation to mineral deposits and volcanic activity.
  • Fractional crystallization holds significant importance regarding mineral deposits and volcanic activity because it influences both the composition of erupting lavas and the concentration of economically valuable minerals. As specific minerals crystallize out of magma during cooling, they can become concentrated in certain areas, potentially leading to rich ore deposits. Additionally, the changes in magma composition due to fractional crystallization can affect volcanic eruptions by altering viscosity and explosiveness, thereby impacting volcanic behavior and hazard assessment.

Related terms

Magma: A molten rock material beneath the Earth's surface that can cool and solidify to form igneous rocks.

Igneous Rocks: Rocks formed through the cooling and solidification of magma or lava, classified as intrusive or extrusive based on where they solidify.

Magmatic Differentiation: The process by which a single magma body evolves into diverse rock types through processes like fractional crystallization and magma mixing.