Marine Sediments

Question 1

why marine sediments are interesting to oceanographers.

Answer 1

Reveals Earth’s history.
Provides clues to past geographic distributions of marine organisms, movements of the ocean floor, ocean circulation patterns climate changes on Earth and global extinction.

Question 2

four primary types of marine sediment

Answer 2

Lithogenous
Biogenous
Hydrogenous
Cosmogenous

Question 3

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

Answer 3

Sea surface Temperature
Nutrient supply
abundance of marine life
atmospheric winds
ocean current patterns
volcanic eruptions
major extinction events 
changes in Earth’s climate
movement of tectonic plates

Question 4

paleoceanography

Answer 4

The study of how the ocean, atmosphere, and land have interacted to produce changes in ocean chemistry, circulation, biology and climate.

Question 5

lithogenous sediment

Answer 5

Derived from pre-existing rock material that originates on the continents of islands from erosion, volcanic eruptions, or blown dust. Also referred to as terrigenous sediment.

Question 6

Characteristics of Lithogenous Sediment

Answer 6

dsaf

Question 7

List the transportation mechanism that carry sediment to the ocean

Answer 7

Streams, wind, glaciers, and gravity.

Question 8

List the submarine transportation mechanisms that carry sediment beyond the continental margin

Answer 8

Turbidity currents

Question 9

In which marine region do the largest marine sedimentary deposits form

Answer 9

Around the margins of the continents.

Question 10

why most lithogenous particles, including most sand (but not Hawai’i sand), are quartz

Answer 10

Quartz is a major component of most rocks and since it is resistant to abrasion it can be transported long distances.

Question 11

the primary sediment transportation mechanism from the Sahara Desert to the ocean.

Answer 11

Prevailing winds

Question 12

list the primary sediment sizes from coarse-grained to fine-grained.

Answer 12

Boulder, cobble, pebble, granule, sand, silt, clay

Question 13

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

Answer 13

Because high-energy transporting media predominate close to shore and lower-energy conditions exist in the deep-ocean basins.

Question 14

Define well-sorted sediment and poorly-sorted sediment.

Answer 14

Well-sorted sediment is sediment composed of particle that are primarily the same size whereas poorly-sorted sediment is sediment that is comprised of a variety of differently sized particles.

Question 15

Define neritic deposits and pelagic deposits.

Answer 15

Neritic deposits are found on continental shelves and in shallow water near islands and are generally coarse grained; pelagic deposits are found in deep-ocean basins and are typically fine grained

Question 16

Decribe the characteristics and formaton of glacial deposits.

Answer 16

Poorly-sorted deposits containing particles ranging from boulders to clays may be found in the high-latitude portions of the continental shelf.

Question 17

Describe the characteristics and formation of abyssal clays.

Answer 17

70% (by weight) fine, clay sized-particles, composed of particles transported great distances and deposited on the deep ocean floor, and are red-brown due to the oxidized iron it contains.

Question 18

biogenous sediment

Answer 18

The remains of hard parts of once-living organisms.

Question 19

Explain why most marine biogenous deposits are called oozes

Answer 19

Because marine biogenous deposits resemble fine-grained, mushy material, or ooze.

Question 20

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

Answer 20

Calcium carbonate (CaCO3) and Silica (SiO2)

Question 21

List two microscopic, planktonic organisms with siliceous tests.

Answer 21

Diatoms and radiolarians

Question 22

List two microscopic, planktonic organisms with calcareous tests.

Answer 22

Foraminifers and coccolithophores

Question 23

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

Answer 23

They need sunlight because they photosynthesize

Question 24

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

Answer 24

Production, destruction, and dilution

Question 25

Explain why biogenous deposits dominate the pelagic sea floor.

Answer 25

Because there is so little lithogenous sediment deposited at great distances from the continents that could dilute the biogenous material.

Question 26

List the three dominate siliceous oozes types.

Answer 26

Diatomaceous ooze, radiolarian ooze, and silicoflagellate ooze

Question 27

List the two dominate calcarous ooze types.

Answer 27

coccolith ooze, foraminifer ooze

Question 28

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

Answer 28

The carbonic acid dissolves calcareous material by the cold waters CO2

Question 29

Define the calcite compensation depth (CCD)

Answer 29

The depth at which the amount of calcite produced by the organisms in the overlying water column is equal to the amount of calcite the water column can dissolve. no calcite deposition occurs below this depth

Question 30

Give the average CCD depth

Answer 30

4500 m

Question 31

Explain the relationship between upwelling and siliceous deposits.

Answer 31

siliceous deposits form below cool surface water regions and upwellings being deep, cld nutrient rich water to the surface.

Question 32

Define hydrogenous sediment

Answer 32

sediment that forms from precipitation from ocean water or ion exchange between sediment and ocean water

Question 33

Describe growth of a Mn nodules

Answer 33

requires extremely low rates of lithogenous nodules or biogenous input so that the nodes are not buried

Question 34

Give the average Mn nodule growth rate.

Answer 34

5mm per million of years