SO461 Geological Oceanography

Fall 2008 Test 2

 

There were three versions of this Exam.  The A version and the B version were significantly different, while the Makeup Version was very similar to the B version

 

Diagrams

4 @ 15 points

60

 

Short answer

4 @ 10 points

40

 

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.

 

Carefully read each question and answer what it asks.  Do not assume that you know what a question is asking, or what a diagram shows.  All answers 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.  Quality and not just quantity counts.

 

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. 

 

Key concepts that should have been incorporated into answers on this exam:

 


 

SO461 Geological Oceanography

Fall 2008 Test 2 Version A

 

 

(15) The map below shows two potential plate boundaries and the earthquakes in the vicinity.  The cross section shows the depths of earthquakes.  Discuss what you can say about the plate tectonic setting of this region, relating the earthquakes, the major features you would see and where they would be located.

 

 

 

 

 

 

 

Marianas Trench, with back-arc spreading

 

 



 

 

 

(15) What does this image measure, and what are on the x and y axes of the figure?

The bottom value on the y axis is 1.5--what does that mean, and what would you have to do to get a useful depth value?

Can you see anything of geological interest on this figure?  If so describe it; if not, state what we generally look for in this data.

 

See seismic reflection lab.

  


 

 

(15) The diagram above shows the sedimentation rates at three locations. 

·         In general, what would you expect to happen to the sedimentation rate as you went deeper into the sea floor.  Why would this happen?  Does any of these profiles follow that expectation?

·         If you wanted to study the Jurassic/Cretaceous boundary, which of the locations would offer the best information from ODP cores?  Why would this be the case?

·         Is it possible for the slope of the curves to be vertical?  Horizontal?  What would those situations indicate if they were possible?

 

J/K boundary is at 208 MY

 



 

(15) The two profiles above show regions in the ocean, with the same vertical and horizontal scales.  What features are depicted, and what is the difference between the two?

 

MAR (top) and EPR (below)

 


 

(10) For the two plate motion diagrams below, show how you would compute the relative motion between the two plates and what type of boundary is represented.  The velocity vectors are labeled, as are the locations of the two plates relative to the boundary.

 

 

 

 

 

 

 

 

 

 

 

Plate motions depicted


 

 

 

 

 

(10) The diagram above shows a fault offsetting two features that appear to be same (A and A’). 

See Figure 7.1 of the text

 

 


 

 

(10) The diagram above shows a portion of the San Andreas Fault, a right lateral strike-slip fault.  Sketch the motion for the fault, and briefly describe what will happen at bend "A" of the fault.

 

SAF motion

 


 

(10) What is the difference between the following rock in terms of their composition and locations where they form:

·         Blueschist and gneiss: 

·         Granite and andesite:

 

 


 

SO461 Geological Oceanography

Fall 2008 Test 2 Version B

 

 

 

(15) The diagram above shows the sedimentation rates at three locations. 

·         In general, what would you expect to happen to the sedimentation rate as you went deeper into the sea floor?  Why would this happen?  Does any of these profiles follow that expectation?

·         If you wanted to study the Cretaceous/Tertiary (KT) boundary, which of the locations would offer the best information from ODP cores?  Why would this be the case?

·         Is it possible for the slope of the curves to be vertical?  Horizontal?  What would those situations indicate if they were possible?

 

K/T boundary is at 65 MY

 

 



(15) Consider the diagram above.

·         What does this image measure, and what are on the x and y axes of the figure?

·         The bottom value on the y axis is 1.2--what does that mean, and what would you have to do to get a useful depth value?

·         Can you see anything of geological interest on this figure?  If so describe it; if not, state what we generally look for in this data.

 

See seismic reflection lab.

 

 


 

 

 

(15) The two profiles above show regions in the ocean, with the same vertical and horizontal scales.  What features are depicted, and what is the difference between the two?

 

 MAR (top) and EPR (below)   See Figures 6.1 and 6.9 of the text

 


 

(15) There was an earthquake yesterday at VANUATU (-17.135˚S,  168.402˚E) with  MW = 6.2 and a focus at 220 km.  The diagrams show the historic seismicity in map view and in cross sections, and the focal mechanism of yesterday's earthquake.  Discuss what you can say about the plate tectonic setting of this region, relating the earthquakes, the major features you would see and where they would be located.

 

 

 

 

 

 



(10) For the two plate motion diagrams below, show how you would compute the relative motion between the two plates and what type of boundary is represented.  The velocity vectors are labeled, as are the locations of the two plates relative to the boundary.

 

 

 

 

 

 

 

 

 

 


Plate motions depicted

 

(10) The diagram above shows a fault offsetting two features that appear to be same (B and B’). 

 

 

 See Figure 7.1 of the text

 


(10) The diagram above shows a portion of the San Andreas Fault, a right lateral strike-slip fault.  Sketch the motion for the fault, and briefly describe what will happen at bend "B" of the fault.

 

  SAF motion


 

(10) What is the difference between the following rock in terms of their composition and locations where they form:

·         Blueschist and gneiss: 

·         Granite and andesite:

 


 

SO461 Geological Oceanography

Fall 2008 Test 2 Makeup Version

 

 

(15) The diagram above shows the sedimentation rates at three locations. 

·         In general, what would you expect to happen to the sedimentation rate as you went deeper into the sea floor?  Why would this happen?  Does any of these profiles follow that expectation?

·         If you wanted to study the Permian/Triassic boundary, which of the locations would offer the best information from ODP cores?  Why would this be the case?

·         Is it possible for the slope of the curves to be vertical?  Horizontal?  What would those situations indicate if they were possible?

 

P/Tr boundary is at 245 MY, and there is no seafloor left from that time period.

 

 



(15) Consider the diagram above.

·         What does this image measure, and what are on the x and y axes of the figure?

·         The bottom value on the y axis is 1.2--what does that mean, and what would you have to do to get a useful depth value?

·         Can you see anything of geological interest on this figure?  If so describe it; if not, state what we generally look for in this data.

 

See seismic reflection lab.

 


 

 

(15) The two profiles above show regions in the ocean, with the same vertical and horizontal scales.  What features are depicted, and what is the difference between the two?

 

 MAR (top) and EPR (below)

 


 

 

(15) There was an earthquake yesterday at VANUATU (-17.135˚S,  168.402˚E) with  MW = 6.2 and a focus at 220 km.  The diagrams show the historic seismicity in map view and in cross sections, and the focal mechanism of yesterday's earthquake.  Discuss what you can say about the plate tectonic setting of this region, relating the earthquakes, the major features you would see and where they would be located.

 

 

 

 

 

 



(10) For the two plate motion diagrams below, show how you would compute the relative motion between the two plates and what type of boundary is represented.  The velocity vectors are labeled, as are the locations of the two plates relative to the boundary.

 

 

 

 

 

 

 

 

 

 

 

Plate motions depicted


 

(10) The diagram above shows a fault offsetting two features that appear to be same (B and B’). 

 See Figure 7.1 of the text

 


(10) The diagram above shows a portion of the San Andreas Fault, a right lateral strike-slip fault.  Sketch the motion for the fault, and briefly describe what will happen differently at bends “A” and "B" of the fault. 

 

SAF motion

 


(10) What is the difference between the following rock in terms of their composition and locations where they form:

·         Blueschist and gneiss:

·         Granite and andesite:

·         Basalt and gabbro:

 







 

Plate Motions depicted

 

Ridge

 

NNR-NUVEL-1A  S47.8354070° E101.903179°

Australia

       70.23 mm/yr   38°

Antarctica

       11.45 mm/yr   129.9°

Plate motion:        71.60 mm/yr  toward 208.5°

Trench

 

NNR-NUVEL-1A  N44.8960838° W125.012453°

North America

       19.66 mm/yr   222°

Juan de Fuca

       19.35 mm/yr   77.0°

Plate motion:        37.26 mm/yr  toward  59.6°

 

 

 

 

SAF Motion

 See Figures 7.9 to 7.11 of the text