Name ______________________ Date ____________ Per ____ Due Date __________
Chemistry of Magma - Does It Tell Us Anything About How a
Volcano Burps?
Overview: Geochemists study the chemical composition of magma to predict patterns of
volcanic eruptions as well as to understand the composition of the Earth's interior. You
will use the chemical composition of the magma to distinguish between the different
types of volcanic rocks. The chemical data will be used to locate on a world map the
different types of volcanoes based on their rock type. You will then use this data to
predict where the most violent eruptions will occur. The Data Sheet includes the latitude
and longitude of selected active volcanoes around the world and the chemical
composition of rocks from each. The chemical composition includes silica dioxide
(SiO2) and iron oxide (Fe2O3).
Directions:
1.
The Volcano Data Sheet shows that rocks from volcanoes are classified
into three different rock types – rhyolite, andesite, and basalt. A scatter plot of the
data from the Volcano Data Sheet is attached. Use the Summary of Magma
Composition Table to help you determine the range of SiO2 for each rock type.
Percentage (%) Range of SiO2 in Magma
Rock Type
rhyolite
andesite
basalt
Range (%)
> 66
52 - 66
< 52
2. Fill in the rock type for all of the volcano locations on the Data Sheet.
3. Using the latitude and longitude coordinates on the Data Sheet, plot all the volcanoes
using a small triangle () on the World Grid Map. Use a different colored pencil for
the rock type associated with each volcano as follows:
Andesite
Rhyolite
Basalt
red
blue
green
Name ______________________ Date ____________ Per ____ Due Date __________
Follow-up Questions:
1. Look at the Plate Tectonics Map on page 83 in the textbook. Describe the general
relationship between the location and type of volcanoes plotted and the type of
tectonic plate boundary (convergent, divergent or transform).
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
2. What happens to the percentage of silicon dioxide (SiO2) as the percentage of iron
oxide (Fe2O3) in volcanic rocks increases? Refer to the Data Sheet to determine the
correlation.
_____________________________________________________________________
_____________________________________________________________________
3. Silicon dioxide (SiO2) in magma is one factor that controls the violence of volcanic
eruptions. Magma from the most violent eruptions has a higher percentage of
silica compared to quiet eruptions. Use the Summary of Magma Composition Table
to complete the chart below. Label the type of eruption as either violent, quiet to
violent or quiet based on percent of SiO2.
Type of Rock
Relative % of SiO2
Most
Intermediate
Least
Type of Eruption
4. Which rock is most associated with a violent eruption?
________________________________________________________________________
________________________________________________________________________
Name ______________________ Date ____________ Per ____ Due Date __________
DATA SHEET
Volcano Location
Pacific U.S.
1. Lassen, CA
2. Crater Lake, OR
3. Mt. Rainier, WA
4. Mt. Baker, WA
U.S. Interior
5. Yellowstone Park, WY
6. Craters of the Moon, ID
7. San Francisco Peaks, AZ
Central America/West Indies
8. Paricutin, Mexico
9. Popocatepetl, Mexico
10. Mt. Pelee, Martinique
11. Santa Maria, Guatemala
12. Mt. Misery, St. Kitts
South America
13. Cotopaxi, Ecuador
14. Misti, Peru
Alaska and Aleutian Islands
15. Katami, Alaska
16. Adak, Aleutians
17. Umnak Island, Aleutians
18. Kamchatka, Russia
Japan
19. Mt. Fuji, Honshu
20. Izu-Hakone, Honshu
East Indies
21. Mayon, Philippines
22. Krakatoa, Java & Sumatra
23. Karkar, New Guinea
Central Pacific
24. Mauna Loa, Hawaii
25. Galapagos Islands
26. Mariana Islands
South Pacific
27. Aukland, New Zealand
28. Tahiti
29. Samoa
North Atlantic
30. Surtsey, Iceland
31. Mid-Ocean Ridge
Africa
32. Kilimanjaro, Tanzania
Latitude
Longitude
% of Magma Composition
SiO2
Al2O3 FeO + Fe2O3
40N
43N
47N
49N
121W
122W
122W
122W
57.3
55.1
62.2
57.4
18.3
18.0
17.1
16.6
6.2
7.1
5.1
8.1
45N
43N
35N
111W
114W
112W
75.5
53.5
61.2
13.3
14.0
17.0
1.9
15.2
5.7
19N
19N
15N
15N
17N
102W
98W
61W
92W
63W
55.1
62.5
65.0
59.4
59.8
19.0
16.6
17.8
19.9
18.3
7.3
4.9
4.5
5.9
7.3
1S
16S
78W
71W
56.2
60.1
15.3
19.0
9.7
5.0
58N
52N
53N
57N
155W
177W
169W
160E
76.9
60.0
52.5
60.6
12.2
17.0
15.1
16.4
1.4
6.9
12.8
7.9
35N
35N
139E
139E
49.8
53.8
20.6
14.8
11.2
13.0
13N
6S
5S
124E
105E
176E
53.1
67.3
60.1
20.0
15.6
16.4
8.2
4.3
9.6
19N
1S
16N
156W
91W
145E
49.6
48.4
51.2
13.2
15.4
17.3
11.9
11.8
10.9
38S
18S
13S
176E
149W
172W
49.3
44.3
48.4
15.6
14.3
13.3
11.9
12.4
12.3
63N
60N
20W
30W
50.8
48.2
13.6
16.5
12.5
11.7
3S
37E
45.6
10.3
12.6
Rock Type
Name ______________________ Date ____________ Per ____ Due Date __________