Download Plate Tectonics II: Transform Faults, Subduction Zones, and Ho

Plates II
Preparation: Geography of the Ocean Basins
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Lab Section:
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Subduction zones, hot spots, and triple junctions are all locations of considerable geologic
activity. Because of the magnitude and nature of this activity, they can have a profound
affect on the societies that are nearby. In light of this importance, these preparation
exercises are intended to familiarize you with the distribution of these features on the
Earth’
s surface. The answers to the following questions can be found in your textbook.
1. Use your textbook and the world map on p. 4 (Fig. 1) to complete the following:
a. Sketch in the Aleutian, Japan, Mariana, Java, Peru-Chile, and Tonga subduction
zones using the standard symbol.
b. Show the position and name the continental subduction zone located in Asia.
2. A major seamount chain occurs in the Pacific Ocean Basin. Find the figure describing
this chain in your textbook and use it to answer the following questions:
a. What are the names of the two segments of the seamount chain?
b. Which of the two segments is older?
c. Which one was formed during the current spreading episode?
d. When did the change in plate motion occur?
e. Complete the following table.
Island/seamount
Name
Age (my)
Oldest
Youngest
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Position on chain
Plates II
Preparation: Geography of the Ocean Basins
3. Which plate is completely surrounded by trenches?
4. Which two plates are not bounded by any trench?
5. What type of boundary is dominant along the Pacific plate’
s margin?
6. How many trenches bound the Pacific plate?
7. Using a map of global seismic activity, complete the following.
a. Along which types of plate boundaries do earthquakes occur?
b. Of the plate boundaries you identified above, which has the deepest earthquakes?
c. Along western South America, what is the position of the earthquakes with respect
to the trenches?
d. What major types of geologic features are common in subduction zones?
e. What geologic events are common at subduction zones?
f. Why are there no deep earthquakes along the west coast of North America?
g. What type of plate tectonic activity produced the Himalayan Mountains?
h. Name the two plates associated with the only subduction zones in the Atlantic Ocean
Basin?
8. Nearly 100 hot spots have been identified around the world. These features are useful
because they define a fixed reference system for studying absolute plate motions.
Answer the following questions about hot spots.
a. Which continents lack hot spots?
b. Which is the fastest moving plate?
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Plates II
Preparation: Geography of the Ocean Basins
c. What is the slowest moving continent?
d. Name the continent that has the most hot spots.
e. The hot spot shown on Fig. 1 is located on the South American plate.
(1) Draw an arrow showing the direction of plate motion in the upper left corner of
the figure.
(2) Draw a line showing the trend of the volcanic chain that will be produced by this
hot spot as the plate moves over it.
(3) Label the end of the line where the oldest seamounts will be found (O) and the
position of the youngest seamounts (Y).
9. Sketch the characteristic profiles of a seamount and a guyot.
a. Why are they different?
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Plates II
Preparation: Geography of the Ocean Basins
Fig. 1: World map for locating subduction zones.
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