In class on Monday, Professor Pillar presented an introductory overview of Bowen’s Reaction Series. The following evening, while reviewing my notes, I came across the diagram I copied from the PowerPoint. Although the diagram was not particularly difficult to follow, I recalled when Professor Pillar stressed how important is was that we understand it. Furthermore, after taking Monday’s exam, I thought it would be a good idea to be capable of reproducing this diagram, in case it appeared on a future exam. Below, I have provided some information and background knowledge pertaining to Bowen’s Reaction Series.
This series was developed by Norman Levi Bowen, who graduated from Queens University (the one in Ontario). Norman Bowen studied geology and physical chemistry, and has an award named after him. He died on September 11, 1956. While studying the crystallization of powdered minerals in a laboratory located in our nation’s capital, Washington, D.C. Bowen devised his reaction series based on when and under what conditions each silicate mineral crystallized. The purpose of Bowen’s Reactions Series is to visually represent the conditions under which different igneous rocks form in an organized way that is easy for the viewer to understand. Bowen’s Reaction Series is important to geologists because it helps them understand the order in which specific minerals were created.
Below is Bowen’s Reaction Series.
As you can see, the diagram is composed of three main parts: the temperature scale on the left, presented in Kelvin, the minerals, which are located in the center, and on the right are the classifications under which the different minerals fall. The different branches of minerals represent the Discontinuous Reaction Series and the Continuous Reaction Series, which are located on the right. The Discontinuous Reaction Series minerals form from already-present crystals, and react with the magma, one step at a time, to become a new mineral. The Continuous Reaction Series minerals gradually and continuously change in the process of becoming a new mineral.
Basically, Bowen’s Reaction Series is a diagram that maps the progression of a mineral with basaltic origins as it changes into other minerals. These processes would take place inside the earth, either deep inside the mantle, or only shielded be a thin layer of the crust. I find it very interesting that a mafic mineral can transform into a felsic mineral.
One flaw with Bowen’s Reaction Series is that his series is based on the assumption that all magma comes from Basaltic magma. However, this is now understood to be a false assumption, and therefore, more reaction series exist than just Bowen’s. His work is still valid, though, and geologists continue to use it.