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OCN 201 Third Reading Discussion Questions

Marine Sediment

Trujillo and Thurman - Chapter 4

1. Read Rachel Carson's quote at the top of page 97, and explain why the oldest parts of the sea floor are flat, muddy plains. (Also see fig. 4.1)

4.1 Why Are Marine Sediments Important?

2. Explain why marine sediments are important to oceanographers.

3. List the past conditions that scientists can infer by analyzing marine sediments.

4. Define paleoceanography. (Also see p. 529)

4.2 What Is Lithogenous Sediment?

5. Define lithogenous sediment. (Also see p. 526)

Origin of Lithogenous Sediment

6. List the transportation mechanims that carry sediment to the ocean. (Also see fig. 4.4)

7. List the submarine transportation mechanims that carry sediment beyond the continental margin. (Also see fig. 3.10 on p. 84)

8. In which marine region do the largest marine sedimentary deposits form?

Composition of Lithogenous Sediment

9. Explain why most lithogenous particles, including most sand (but not Hawai'i sand), are quartz. (Also see fig. 4.5)

10. Give the primary sediment transportation mechanism from the Sahara Desert to the ocean. (Also see fig. 4.6)

Sediment Texture

11. Use table 4.2 to list the primary sediment sizes from coarse-grained to fine-grain.

12. Explain why lithogenous sediments tend to become finer with increasing distance from shore.

13. Define well-sorted sediment and poorly-sorted sediment. (Also see p. 532)

Distribution of Lithogenous Sediment

14. Define neritic deposits and pelagic deposits.

15. Describe the characteristics of abyssal clays.

4.3 What Is Biogenous Sediment?

16. Define biogenous sediment. (Also see p. 518)

Origin of Biogenous Sediment

17. Explain why most marine biogenous deposits are called oozes. (Also see p. 528, and figs. 4.7 and 4.8)

Composition of Biogenous Sediment

18. List the two primary biogenous sediment compositions: name and chemical formula.

Silica

19. List two microscopic, planktonic organisms with siliceous tests. (Also see figs. 4.7 and 4.8)

Calcium Carbonate

20. List two microscopic, planktonic organisms with calcareous tests. (Also see figs. 4.8 and 4.9)

21. Explain why diatoms and coccolithophores live near the ocean's surface.

Distribution of Biogenous Sediment

22. List the three factors that control the formation of biogenous oozes.

Netritic Deposits

23. Which of the three factors results in relatively fewer biogenous deposits in the netritic environment compared to the pelagic environment?

Pelagic Deposits

24. Explain why biogenous deposits dominate the pelagic sea floor.

Siliceous Ooze

25. List the three dominate siliceous oozes types.

Calcareous Ooze and the CCD

26. List the two dominate calcarous ooze types.

27. Explain why calcareous oozes are rarely form on the deep-sea floor.

28. Define the calcite compensation depth (CCD). (Also see p. 518, and figs. 4.12 and 4.13)

29. Give the average CCD depth. (Also see fig. 4.13)

30. Explain why calareous deposits are seen below the CCD. (Also see fig. 4.13)

31. Explain the relationship between upwelling and siliceous deposits. (Also see table 4.3)

4.4 What Is Hydrogenous Sediment?

32. Define hydrogenous sediment. (Also see p. 524)

Composition and Distribution of Hydrogenous Sediment

33. Describe growth of a Mn nodules. (Also see fig. 4.15)

34. Explain why Mn nodules only form in the deep ocean floor.

35. Explain the Mn nodules are economically valuable.

36. Give the average Mn nodule growth rate.