Fractional crystallization

Definition

Fractional crystallization is a geological process where different minerals crystallize from a cooling magma at different temperatures, leading to the separation of minerals based on their unique crystallization points. This process is significant because it helps explain the formation of diverse igneous rock types and contributes to the development of mineral deposits by concentrating valuable elements as the molten rock cools and solidifies.

5 Must Know Facts For Your Next Test

1. As magma cools, minerals with higher melting points crystallize first, followed by those with lower melting points, leading to a sequence of mineral formation.
2. Fractional crystallization plays a key role in the differentiation of magma, allowing for the formation of various igneous rocks with distinct mineral compositions.
3. The process can create layered intrusions, where different mineral layers reflect the cooling history of the magma body.
4. Fractional crystallization is essential for forming economically important mineral deposits, as it can concentrate specific metals or elements in certain areas.
5. The resulting differences in mineral composition due to fractional crystallization can lead to the creation of diverse rock types such as basalt, granite, and diorite.

Review Questions

• How does fractional crystallization influence the diversity of igneous rocks?
  • Fractional crystallization impacts the diversity of igneous rocks by controlling which minerals crystallize from magma at varying temperatures. As magma cools, different minerals form at specific points along Bowen's Reaction Series. This leads to unique combinations of minerals in rocks, resulting in various igneous rock types like basalt and granite, each with its own distinct characteristics and uses.
• Discuss the role of fractional crystallization in the formation of ore deposits.
  • Fractional crystallization plays a crucial role in forming ore deposits by concentrating valuable minerals as magma cools and solidifies. During this process, certain elements become more abundant in specific mineral phases that crystallize at lower temperatures. These concentrations can lead to economically viable deposits, making fractional crystallization an essential factor in mineral resource exploration and extraction.
• Evaluate how understanding fractional crystallization can aid in predicting the composition of igneous rocks formed in different geological settings.
  • Understanding fractional crystallization allows geologists to predict the composition of igneous rocks by analyzing the cooling history and mineral content of a magma body. By applying concepts like Bowen's Reaction Series, they can determine which minerals are likely to form at given temperatures and pressures. This knowledge aids in interpreting geological processes and identifying potential resource locations based on expected mineral assemblages in specific environments.

Related terms

Bowen's Reaction Series: A conceptual model that explains the order in which minerals crystallize from magma as it cools, illustrating the relationship between mineral composition and temperature.

Magma Differentiation: The process by which a single magma body evolves into several distinct rock types through processes like fractional crystallization and partial melting.

Ore Deposits: Concentrations of valuable minerals or metals that can be economically extracted, often formed through processes including fractional crystallization.