Why is bowens reaction series useful

As with everything else in geology, there are exceptions to this rule see Strickler's 1st Law of GeoFantasy , but for the most part it works. Bowen determined that specific minerals form at specific temperatures as a magma cools. At the higher temperatures associated with mafic and intermediate magmas, the general progression can be separated into two branches. The continuous branch describes the evolution of the plagioclase feldspars as they evolve from being calcium-rich to more sodium-rich.

The discontinuous branch describes the formation of the mafic minerals olivine, pyroxene, amphibole, and biotite mica. The continuous series is a plagioclase feldspar. At high temperatures, the high-calcium variety of anorthite forms. Then as temperatures fall it is replaced by more sodium-rich varieties: bytownite, labradorite, andesine, oligoclase, and albite.

As the temperature continues to fall, these two series merge, and more minerals crystallize in this order: Alkali feldspar, muscovite, and quartz. A minor reaction series involves the spinel group of minerals: chromite, magnetite, ilmenite, and titanite.

Bowen placed them between the two main series. The complete series is not found in nature, but many igneous rocks display portions of the series. The main limitations are the state of the liquid, the speed of cooling and the tendency of mineral crystals to settle under gravity:. All of these factors affect the course of a magma's evolution—its differentiation. Bowen was confident that he could start with basalt magma, the most common type, and build any magma from the right combination of the three.

But mechanisms that he discounted—magma mixing, assimilation of country rock and remelting of crustal rocks—not to mention the whole system of plate tectonics he did not foresee, are much more important than he thought. Today we know that not even the largest bodies of basaltic magma sit still long enough differentiate all the way to granite. Actively scan device characteristics for identification.

Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance. He also saw that minerals occur together in rocks with others that crystallize within similar temperature ranges, and never crystallize with other minerals. This relationship can explain the main difference between mafic and felsic igneous rocks. Mafic igneous rocks contain more mafic minerals, and therefore, crystallize at higher temperatures than felsic igneous rocks.

This is even seen in lava flows, with felsic lavas erupting hundreds of degrees cooler than their mafic counterparts. Boehler, R. Annual Review of Earth and Planetary Sciences 24 , 15—40 Bowen, N. The evolution of the igneous rocks.