PLATE TECTONICS LAB

Historical Geology - GEOL 1122 - D. Askren

INTRODUCTION

In this lab, you will first learn how to access the Internet. Then, you will review the basic types of Plate Tectonic boundaries by viewing data from classic examples of each type. After this, you will identify the types of boundaries present at various worldwide locations by comparing these to the classic examples. From my home page (http://vulcan.gsw.peachnet.edu/daskren), go to the Geoscience II selection from Course Assignments.

- This will then give you several options. Select Plate Tectonics Lab

- You have made it! By selecting options from the menu bar, you can access all of the major sections of the lab.

- For example, select -Instructions- for introductory information.

- To return to this main lab MENU, select Return to Plate Tectonics Lab MENU.

 

CLASSIC PLATE TECTONIC BOUNDARIES


A. Convergent Boundary (Ocean è çContinent) - western South America


Topography:

The west coast of South America is the world's best example of this type of plate boundary. As the ocean plate pushes against the continent, the former is subducted beneath the continent, producing earthquakes, volcanoes, and mountain building. View the topography of this region by selecting South America from the TOPOGRAPHY section. Return to the Plate Tectonics Lab MENU when complete with this section.

1. Where are the Andes Mountains, relative to the coastline?

2. Where is the plate boundary, relative to the coastline?

3. What two plates are converging at this plate boundary?

4. Summarize this topographic information on the accompanying Summary Chart of Plate Tectonic Boundaries

 

Seismicity:

View the seismicity (earthquake activity) of the area by selecting South America from the Seismic Activity section:

5. How many earthquakes have affected this ares since 1975?

6. What is the maximum depth of earthquakes here?

7. What type of faulting produced these quakes?

8. Why are the earthquakes deepest to the east (>500 km) and shallowest to the west (< 33 km)? Think about subduction zones

 

Volcanism:

View images of the region's volcanic activity by selecting western South America from theVOLCANIC ACTIVITY section:

9. What type of volcanic rocks are present along this type of plate boundary (hint: what is the name of the mountain range)?

10. Relative to the earthquakes and mountain range, where are volcanoes located on the South American continent?

 

11. Summarize the above seismic and volcanic information on the accomanying Summary Chart of Plate Tectonic Boundaries

 

 

 


B. Convergent Boundary (Continent è çContinent) - central Asia


Topography:

The boundary between India and Asia is the world's best active example of colliding continents. Here, India is pushing beneath and lifting Asia, as the two plates converge. Select central Asia from the TOPOGRAPHY section to view the topography of this region.

1. Where are the Himalayan Mountains, relative to the boundary between Asia and India?

2. Prior to their collision, what was between India and Asia?

3. What two plates are converging at this boundary?

4. What types of rocks are present on these (and most ) continental plates?

 

Seismicity:

View the seismicity (earthquake activity) of the area by selecting central Asia from the SEISMIC ACTIVITY section:

5. How many earthquakes have affected this ares since 1975?

6. What is the maximum depth of earthquakes here?

7. What type of faulting produced these quakes?

8. Why are the earthquakes shallower (<300 km) than the deepest quakes observed in western South America (previous section)?

  

Volcanism:

View information on the region's volcanic activity by selecting central Asia from the VOLCANIC ACTIVITY section:

9. Why is the nature of volcanism different at this convergent boundary than the convergent boundary along western South America ?

10. Summarize the above information on the accomanying Summary Chart of Plate Tectonic Boundaries

 

 

 


C. Divergent Boundary (çPLATE PLATE è) - South Atlantic Ocean


Topography:

The mid-Atlantic Ridge, along the seafloor of the Atlantic Ocean, results from tensional stress pulling the ocean floor apart. New seafloor forms as magma from the mantle pours onto the surface at these divergent plate tectonic boundaries. View the topography of this region by selecting South Atlantic Ocean from the TOPOGRAPHY section.

1. Does the mid ocean ridge trend generally North-South or East-West?

 2. Describe the trend of the mid ocean ridge relative to the shoreline of eastern South America and western Africa.

 3.What plate is being pulled apart by this divergent plate boundary?

 4. Summarize this information on the accompanying Summary Chart of Plate Tectonic Boundaries

 

Seismicity:

View the seismicity (earthquake activity) of the area by selecting South Atlantic from the SEISMIC ACTIVITY section:

5. How many earthquakes have affected this ares since 1975?

6. What is the maximum depth of earthquakes here?

7. What type of faulting produced these quakes?

8. What type of stress has produced these faults?

9. Why are these earthquakes shallower than those along convergent boundaries.

 

 Volcanism:

View images of the region's volcanic activity by selecting South Atlantic from the VOLCANIC ACTIVITY section:

10. What type of volcanic rocks are present along this type of plate boundary?

11. Why is Ascension Island located directly onto of this plate boundary?

12. Summarize this information on the accompanying Summary Chart.

 

 

 


D. Transform Boundary (PLATE | | PLATE) - western North America


Topography:

The west coast of North America, along southern California, is an excellent example of a transform plate tectonic boundary. Here, an ocean late and a continental plate are grinding past each other. Motion is horizontal (rather than vertical), so little change in topography is associated with the boundary. View the topography of this region by selecting western North America from the TOPOGRAPHY section.

1. What two plates are moving along this plate boundary?

 2. Where is the plate boundary, relative to the coastline?

 3. Explain why mountains along this boundary are lower than those of the Andes or Himalayan Mountains.

 4. Summarize this information on the accompanying Summary Chart of Plate Tectonic Boundaries

 

Seismicity:

View the seismicity (earthquake activity) of the area by selecting western North America from the SEISMIC ACTIVITY section:

5. How many earthquakes have affected this ares since 1975?

6. What is the maximum depth of earthquakes here?

7. What type of faulting produced these quakes?

8. Is the Baja Peninsula on the Pacific Plate or the North America plate?

9. Why are the earthquakes here shallow?

 

Volcanism:

View information on the region's volcanic activity by selecting southwest North America from the VOLCANIC ACTIVITY section:

10. This plate boundary involves a continent and an ocean plate. So does that which produced the Andes Mountains (S. America). Explain why the nature of volcanic activity is different here.

 11. Summarize this information on the accompanying Summary Chart.

 

 

 


E. Passive Plate Boundary


 No relative plate motion occurs along passive plate boundaries. Instead, two adjacent plates are locked together. No mountain building, no seismic activity, and no volcanism is present at such locations. I have completed most of this row in your Summary Chart (row E), however you must locate one example of such a boundary from the remaining locations:

northwest North America

eastern North America

Japan

Iceland

Africa

eastern South America

 

Compare the data I have placed in your Summary Chart to the information from these locations, and determine which is an example of a passive plate boundary. Record your answer in the Summary Chart.

  

 

 

  GLOBAL PLATE TECTONIC BOUNDARIES

You should now be familiar with the specific types of topography, seismicity and volcanic activity associated with each type of plate boundary. You should be able to identify the type of boundary present at other locations by comparing their topographies, seismicities and volcanic histories to the Classic Boundaries studied above (rows A - E in your Summary Chart). Collect data for at least two of the following areas, then compare this data to the Classic Boundaries to determine the type of boundary present at each:

northwest North America

Japan

Iceland

Africa