SO461 Geological Oceanography

Fall 2013 Test 2

Definitions

5 @ 5 points

25

Diagrams

3 @ 15 points

45

Short answer

3 @ 10 points

20

Total

100

Authorized reference:

  1. This test will be open book.  Students can use their own copy of the textbook, with any notes they have permanently written in it.  No papers can be attached to the text, and class notes and handouts will not be allowed. Books will not be shared during the exam.
  2. Calculators will not be allowed.  For the calculations, you may set it up and leave the answer in terms of a sum, product, or quotient, or you can make reason simplifications to get a rough idea of the answer.

Definitions:  clearly indicate what the term means, and what its importance to geology is.  You must answer 5 of the 6 questions.

Diagrams: These should clearly indicate understanding of the procedures and concepts involved, and should be well thought out with appropriate terms and details to support your answer.  You must answer all 3.

Short Answer: The questions should be answered with several sentences (no more than a short paragraph). You must answer 3 of the 4 questions.

Budget your time.  If you try to look up everything in the text book, you will run out of time.  Do not leave anything blank, and note that I am looking for an understanding of the important concepts and appropriate use to terminology.  An answer than does this will get more credit than finding and copying a sentence in the book that includes the word.

All work on this exam is individual.  You may not any materials (books, notes, computers), not listed above and you may not use IM, texting, talking, or any other means to communicate with other individuals.



Definitions: Fill out the table below for 5 of the 6 terms.  Each is worth 5 points, so you should be

Term:

Definition                                                 

Importance to geology                                             

APW:

VLBI

Total reconstruction pole

Large igneous province

Geosyncline

Paleolatitude

Insure one term in left completely blank or crossed out.


Diagrams.  You must answer all of the questions on the next 3 pages.  Each is worth 15 points, so insure that you provide a quality answer.

1.  The two diagrams below cover areas of the seafloor about 1250 km across.  Discuss the features you see in the diagrams, and what accounts for the differences between the two areas.



2.  This diagram shows a seismic reflection line through a salt dome (halite); the surrounding rocks are limestone and sandstone.  Note that the diagram has been annotated.

Rock

Sound Velocity (m/sec)

Halite

4500 m/sec

Limestone and Sandstone

5000 m/sec

What do the black lines in the profile (not the annotation) show?

How deep can we image in the sandstone and limestone on the edges of the figure? (Compute a number, and insure your method is clear).

How deep can we image in the halite in the center of the figure? (Compute a number, and insure your method is clear).

Note that the bedding in the sandstone and limestone appears to bend upward where it comes into contact with the halite?  Do you think this is real?  Why or why not?


3. The figure above shows a single velocity diagram for two plates, and then 4 maps showing the orientation of a plate boundary, and the location of the two plates.  Fill in the following table, indicating if the map shows a possible plate configuration, and if so, the type of plate boundary.

Map

Possible Configuration?

If Possible, Boundary type

Map 1

Map 2

Map 3

Map 4

What is the rate of plate motion which applies to all possible configurations?  Provide the number, and the most reasonable units.

Is that the full rate, or the half rate?

Are there any of the boundaries where the other measure (full or half rate) is applicable?  If so, which, and why?



Short Answers.  You must answer 3 of the 4 questions.

1. Drilling cores in the ocean usually includes logs for porosity, density, and sound velocity.  Do these vary in a systematic map (why or why not), and for what other studies are these parameters especially important?

2.  Why will triple junctions typically migrate?

3.  As you move along a spreading center like the East Pacific Rise, what will happen to the spreading rates?  Why does this happen?

4.  How would you recognize an unconformity in a drilling record, and what does it represent?  Do you think it would show up in a seismic reflection line?

Insure that you left one of the short answer questions blank (or crossed out).