SO461 Geological Oceanography

Fall 2016 Test 1

 

Definitions

4 @ 7 points

28

 

Diagrams

6 @ 12 points

72

 

Total

 

100

 

 

Authorized reference:

  1. You may use one 3”x 5” card, personally hand written on both sides, during the exam.  You will turn it in with 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.

 

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 6 of the 7 questions.

 

 

Budget your time.   Do not leave anything blank, and note that I am looking for an understanding of the important concepts and appropriate use of  terminology.

 

All work on this exam is individual.  You may not any materials (books, notes, computers) other than your personal 3”x5” note cared, and you may not use IM, texting, talking, or any other means to communicate with other individuals.  If you are caught with an electronic device that is not turned off and inaccessible you will get a 0 on the exam.

 

 


Definitions: Answer 4 of the 5, for 7 points each.  Indicate why each is important.

  


  

You must answer all 6 of the remaining questions, for 12 points each.  Each has a figure or table.

 

Figure 1.  Geoid anomalies from the TOPEX/Poseidon altimeter, Cycle 364: (A) Orbit 8, (B) Orbit 48, and (c) Orbit 51.

 

How is the geoid anomaly computed, and what does the altimeter actually measure that enables it compute the geoid?

 

 

 

How can the altimeter measure something else that would be of interest to oceanographers rather than geologists?

 

 

 

The three profiles have different vertical and horizontal scales.  What plate tectonic feature do you think is causing each anomaly and why do you think this?

 

A:

 

 

B:

 

 

C:


 

Figure 2.  Drilling results from ODP Leg 166.

 

Which site has the fastest sedimentation rate?  Approximately how fast is it?  (Set up the computation, and show how you got the numbers).

 

What happens around 800 mbsf in Site 1003?

 

 

What happens around 50 mbsf in site 1007?

 

 

In the two deeper holes, do the sedimentation rates appear to increase or decrease as you go downward in the holds?  Is this unusual for these holes, or a common occurrence?

 

Can you make any predictions about P-wave velocity, density, and porosity as you go down the hole?



Figure 3.  Profiles drawn on two different continental margins.  Note sea level shown on each, and that the scales on each differ slightly.  Both have about 50 times vertical exaggeration.

 

How should the locations for these profiles have been drawn?  Why?

 

Why do we use vertical exaggeration?

 

 

How do these two margins differ?

 

 

Could these be from the same continent?

 

 

What is the age of the crust on the right side of each profile?  How can you say this?



 

 

Figure 4.  Motions along a plate boundary.  This is the vector resultant of the two plate's relation motion.

 

 

Could this plate boundary be a subduction zone?    How would you have to interpret the vectors for this to be true, or why cannot it be a subduction zone?

 Trench if the motion must be the motion of Plate 2 with Plate 1 stationary.  If two were stationary, it would be a ridge.

 

Could this plate boundary be a conservative plate boundary?    How would you have to interpret the vectors for this to be true, or why cannot it be a conservative plate boundary?

 

 

 

 

Can you locate the Euler pole for this motion from the information on the map?

 

 

What are the units for the plate motions?

 

 


 

Figure 5.  Velocity diagram and two possible plate maps.

 

 

Is Map A possible with the velocity diagram on the left?  Why or why not, and what kind of plate boundary would it be?

 

 

 

Is Map B possible with the velocity diagram on the left?  Why or why not, and what kind of plate boundary would it be?

 

 

 

 

Is this fast or slow plate motion?

 

 

 

Do we know if this is the absolution motion of these two plates?

 

 

 

Can you say anything about the Euler pole with just a single point’s velocity?



 Table 2.   Sediment recovered at IODP site 2017.

Sediment type

 

Environment

Glacial sediments

 

 

Diatom oozes

 

 

Abyssal red clay

 

 

Radiolarian ooze

 

 

Abyssal red clay

 

 

Calcareous ooze

 

 

MORB

 

 

 

Indicate something about the depositional environment for each layer in the space provided.

 

Is there any way this collection of sediments could be found at a single IODP site  Why or why not?