SO461 Geological Oceanography

Spring 2002 Test 2

 

 

Definitions	10 @ 3points	30
Short answer	5 @ 5 points	25
Longer answer	3 @ 15 points	45
Total		100

 

 

Definitions: answer with no more than a single sentence.  You should be complete and show you clearly understand the term.  Note that you need only answer 10 of the 12.

Short Answer: The questions should be answered with several sentences (no more than a short paragraph). You must answer four of the six questions.

Longer Answer: These should clearly indicate understanding of the procedures and concepts involved.

 

Note that on both the definitions and short answer you have a choice of which questions to answer.

 

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Definitions. Define 10 of these 12 terms

 

• Blueschist:

• Turbidite:

• Transpression:

• Orogeny:

• Extrusion tectonics:

• Aulacogen:

• Wilson cycle:

• Backstripping:

• Beta

• Inversion:

• VLBI:

• Reconstruction pole:

Short Answer.  Answer 5 of the 6 questions on this and the next page.  You do not have to use complete sentences, but must clearly indicate that you understand the concepts involved.

 

 

1.  This diagram shows the absolute velocities in the hotspot reference frame for two plates, with the vectors labeled.  Plate Pac is on the left, and JdF on the right.

• What kind of boundary is depicted?
• How could you determine the relative velocity between the two plates?  (You need not actually compute it, just show or describe how you would).
• How could you determine where the pole of rotation between the two plates was located?

 

 

2.  What is the geologic feature show in this diagram (6.9 of the text), and how do the top and bottom figures differ?

 

 

3.  The San Andreas is a right lateral fault.  Draw a sketch to illustrate what this means.  Then draw another sketch to show how the motion would vary along a transform fault and a strike-slip fault with the same geometry.

 

 

4.  Discuss the development of paired metamorphic belts, and how they can be used to unravel the plate history of a region.

 

 

5.  There is a law of superposition of geology.  How would you use it to explain

• The ages of thrust slices in an accretionary prism, and
• The ages of the clasts in conglomerates or sandstones in a foreland basin.

 

6.  Describe how suspect terranes form, and what features in today’s oceans might become the suspect terranes of the future.

 

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Longer Answer.  Answer all three of these questions.

 

I.  This diagram shows the focal mechanism for the recent earthquake in Afghanistan, and the plate boundaries.  What kind of fault ruptured to produce the earthquake, and how can you relate the fault to tectonic processes in the region?

 

02/03/27 08:52:51.84

HINDU KUSH REGION, AFGHANISTAN 

Epicenter:  35.918   69.285

M_W 5.6

 

 

 

 

 

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II.  This diagram shows the distribution of earthquakes by longitude and depth for a region.  What process could cause this distribution, and what kinds of earthquakes would you expect to see in this area?

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III.  This diagram is based on the work of Brian Wernicke.  It shows two cross sections through the crust, with a location map showing where they are located.  Discuss the formation of these features, and how they vary.