Name ______________________________________________________ Per. _____
Bowen’s Reaction Series Simulator – A Computer Lab http://www.gly.fsu.edu/~parker/exercises/ig/Ig8.html#HERE
For this Internet Exercise, you will have an opportunity to interact with a Bowen's Reaction Series Simulator.
This will allow you to explore interrelations between magma chemical composition, cooling rate, and other magmatic processes such as fractionation. You can also create a variety of igneous rock textures by varying the cooling rate during the crystallization process. Thus, using this remarkable simulator, you can gain insight into the complex processes that account for the bewildering variety of igneous rocks.
Directions: Go to the Bowen's Reaction Series Simulator and read the introductory chapters.
Once you feel comfortable with the instructions, click on the "here" button to begin the simulation. Note that you must move the cooling rate slide bar before anything will happen.
Once you have positioned the cooling rate bar, you will see the temperature begin to decrease.
1.
Start with a mafic magma composition and 2 on the cooling r ate (slow). Nothing will happen until the temperature drops below 1400 C. As soon as the temperature drops below 1400, stop the cooling (slidebar to the left) until the crystals have a chance to grow, then resume cooling at a rate of 1-2. The first crystals to form are Olivine. Soon, a
Ca Plagioclase also appears. Crystals from both these minerals will continue to grow until
1200 C, when Pyroxene begins to crystallize. a.
What happens to the Olivine? b.
Why? c.
At about 1000 C all the crystallization is complete. When the temperature reaches 600
C, any remaining liquid quenches to form glass. Assuming that the minerals average at least several millimeters in size, what rock have you just formed?
2.
Now restart the simulation by closing its window and pressing cooling rate (8 on the slidebar).
. This time, try a faster a.
What was the result? b.
Where the crystals larger or smaller? c.
If the crystal size is substantially smaller than 1 mm, what is the rock? d.
And how (where) would it likely form?
Olivine Pyroxene Amphibole Plagioclase Biotite K Feldspar Muscovite Quartz

Name ______________________________________________________ Per. _____
3.
Restart the simulation and push the button marked "quench". What do you get?
4.
Let's try a magma of intermediate composition. Restart the simulation and move the magma composition bar to "intermediate" and then start cooling at a moderate rate (4). a.
What is the first mineral to form? b.
The brown mineral which forms below 1050 C is Amphibole and the black mineral below 800 is Biotite. When the rock finishes cooling (~600 C) what is it?
5.
Now try a magma with felsic composition. Restart the simulation and move the magma composition bar to "felsic" and then start cooling at a moderate rate (4) a.
What is the first mineral to form? b.
When the cooling process is finished, what is it?
6.
One final experiment involves fractionation. Restart the simulation and move the magma composition bar to "mafic" and then start cooling at a moderate rate (4). Wait until the temperature is
1300 C and push the "fractionation" button. The crystalized minerals will settle out and the magma composition will be re-calculated to sum to 100% - then the crystalization process will continue. a.
How is the rock that forms this way different from the rock you formed without fractionation?
Olivine Pyroxene Amphibole Plagioclase Biotite K Feldspar Muscovite Quartz
Warning:
Magma crystallization is much more complex than this simple exercise can simulate!