XII. Continental Margins (40 Points).

D. Compare & contrast the evolution of the New Jersey continental margin with that

of the Georgia continental margin. (5 pts.).

I. Continental Margins (20 Points). Below is a cross-section across the

northern Bay of Biscay passive continental margin. Answer & do the following:

1. Sketch in the oceanic, transitional & continental crustal boundaries, & label each crustal type. (6 pts.)

2. What type of fault occurs at "X"? (2 pts.)

3. At what depth does the dashed boundary at "Y" occur 100 kilometers to the

northeast? (2 pts.)

4. How has the crust above the dashed boundary at "Y" responded to tensional forces?

(2 pts.)

5. How has the crust below the dashed boundary at "Y" responded to tensional forces?

(2 pts.)

6. Why does the fault at "X" sole out at the dashed boundary at "Y"? (3 pts.)

7. What kind of sediments would you expect to find at "Z"? (3 pts.)

8. What rifting process is best explained by this cross-section? (2 pts)

I. Continental Margins: Introduction and Passive (40 Points). Answer and do the following:

A. Answer the following questions. (10 pts.)

1. What are the types of continental margins?

2. Which types are plate boundaries, which are not plate boundaries, and which may or may not be plate boundaries?

3. What type dominates the Atlantic, Pacific and Indian Oceans respectively?

VII. Continental Margins (15 Points). Briefly describe the three types of continental margins and their relationships to plate tectonics

B. Answer the following questions. Use sketches if you wish. (10 pts)

1. What kind of crust is associated with positive isostatic gravity anomalies? Why?

2. What kind of crust is associated with positive free air gravity anomalies? Why?

C. Draw a schematic cross-section to 40 km depth across the passive margin off Georgia, showing crustal thickness, boundaries between oceanic, continental and transitional crust, sediment thickness, sediment type, approximate sediment age and correct topography. Label the depth axis. (15 pts).

C. Briefly explain the reasons that the thick sediments at passive continental margins must result from both of passive sediment loading and active tectonic subsidence. Use sketches if you wish. (15 pts.)

B. Briefly describe why the thick accumulations of shallow-marine sediments occurring at passive continental margins cannot have formed from the effects of sediment loading alone. Use sketches if you wish. (10 pts.)

(10 points) A. Draw a schematic structure section across the New Jersey continental margin out to the crest of the Mid-Atlantic Ridge showing lithospheric, crustal and sediment thickness. Label crustal type.

(10 points) B. Draw a schematic cross-section across the passive margin off New Jersey showing crustal thickness, boundaries between oceanic, continental and transitional crust, sediment thickness, sediment type, approximate sediment age and correct topography.

A. Draw a schematic structure section across a typical continental margin out to the crest of the Mid-Atlantic Ridge showing lithospheric, crustal and sediment thickness. Label crustal type. (20 pts.)