GLY 150 Homework Ch 4
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West Virginia University,Parkersburg *
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150
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Geology
Date
Apr 3, 2024
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docx
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Chapter 4 Homework
1.
4.1 Using table 4.1, list and describe the characteristics of the four main types of marine sediment
a.
The four main types of marine sediment are lithogenous, biogenous, hydrogenous, and cosmogenous. Lithogenous are derived from rock while biogenous are from organisms. Hydrogenous are from water and cosmogenous are from outer space. 2.
4.1 Describe the process of how a drill ship like JOIDES Resolution obtains core samples from the deep-ocean floor. a.
Drill ships have very large towers that contain a long coring mechanism that can reach the deep-ocean floor. The JOIDES Resolution confirmed that seafloor spreading exists by collecting deep-ocean sediments. 3.
4.1 What types of past environmental conditions can be inferred by studying cores of sediment?
a.
By studying cores of sediment, you can infer several past environmental conditions including the nutrient supply, volcanic eruption, extinction events, marine life, and surface temperature.
4.
4.2 Describe the origin, composition, texture, and distribution of lithogenous sediment. a.
Lithogenous sediment originates from small pieces of eroded rock. The texture becomes much finer the farther it is out to the sea. This is caused by an increase in weathering on the ocean floor. The sediment appears everywhere on the ocean floor, regardless of the location. 5.
4.2 Why is the most lithogenous sediment composed of quartz grains? What is the chemical composition of quartz?
a.
Most lithogenous sediment is composed of quartz grains because it is often eroded. Lithogenous sediment is caused by pieces of eroded rock. Quartz is made of silicone and oxygen and
is plentiful on earth.
6.
4.2 What is the difference between neritic and pelagic deposits? Give examples of lithogenous sediment found in each. a.
Neretic deposits are rough, grainy sediments typically found close to the shore and on continental shelves. Pelagic deposits are fine, grained sediments typically found in deep waters and open ocean. Lithogenous sediments are typically neretic. 7.
4.3 Describe the origin, composition, and distribution of biogenous sediment. a.
Biogenous sediments are derived from the remains of organic life. They are made from silicate and calcium carbonate. These sediments are found throughout pelagic waters and help to increase productivity. 8.
4.3 List the two major chemical compounds of which most biogenous sediment is composed and two examples of the microscopic organisms
that produce them. Sketch and label these organisms
a.
Most biogenous sediment is composed of silica and calcium carbonate. Calcium carbonate is derived from forminifera and silica is derived from radiolarians and diatoms. b.
9.
4.3 Technically, what must a biogenous ooze contain to be classified as ooze? What other component do all oozes contain?
a.
In order to be classified as ooze, it must contain very little lithogenic sediment and be rich in silica or calcium carbonate. The sediments are so small that they typically get classified as oozes.
10.
4.3 If siliceous ooze is slowly but constantly dissolving in seawater, how can deposits of siliceous ooze accumulate on the ocean floor?
a.
Siliceous ooze accumulates on the ocean floor because it sinks to
the bottom faster than water can dissolve it. The ooze beneath the top layer of ooze does not touch the water, therefore, it does not dissolve. 11.
4.3 Explain the stages of progression that result in calcerous ooze existing below the CCD. a.
Calcareous ooze that sinks beneath the CCD will automatically be
dissolved unless it is being covered by silicate ooze or clay. CCD is
very acidic, has high pressure, lower temperature, and more carbon dioxide. 12.
4.4 Describe the origin, composition, and distribution of hydrogenous sediment. a.
Hydrogenous sediment originates from chemical reactions occurring within the water, causing specific minerals to come out of the solution or precipitate. They are distributed in a variety of diverse environments including Death Valley, CA. This sediment is composed of phosphates, metal sulfides, carbonates, and manganese nodules. 13.
4.4 Describe manganese nodules, including what is currently known about how they form. a.
Manganese nodules tend to be round, hard lumps of iron, manganese, and other metals. In order to form, it requires a low rate of biogenous input or lithogenous so the nodules do not end
up buried. 14.
4.5 Describe the origin, composition, and distribution of cosmogenous sediment. a.
Cosmogenous sediment is derived from macroscopic meteor debris of microscopic iron-nickel and silicate spherules. These result due to asteroid collisions and other impacts. Small amounts of cosmogenous sediment tend to be mixed into other types of oceanic sediment.
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15.
4.5 Describe the most common types of cosmogenous sediment and give the probable source of these particles. a.
The most common types of cosmogenous sediment are microscopic spherules and macroscopic meteors. Microscopic spherules tend to be composed of silicate rock material. Macroscopic meteors are made of iron, nickel, and silicate. 16.
4.6 Why is it so rare to find a pure marine sediment type? Give some examples of mixtures of sediment. a.
It is rare to find a pure marine sediment type because lithogenous and biogenous sediment is rarely pure deposits containing no amount of other types of sediment. Therefore, most marine sediments found are mixtures. Clay also has a tendency to mix with sediments. 17.
4.6 Why is lithogenous sediment the most common neritic deposit? Why are biogenous oozes the most common pelagic deposits?
a.
Lithogenous sediment is the most common neritic deposit due to
neretic depositing being close to the shore. This is where lithogenous sediments are created. Biogenous oozes are the most common pelagic deposits because they are created in productive areas of the ocean. Pelagic areas are the most productive areas of the ocean. 18.
4.6 How do fecal pellets help explain why the particles found in the ocean surface waters are closely reflected in the particle composition of the sediment directly beneath? Why is this unexpected?
a.
Fecal pellets are a result of organisms living above and their particle composition reflects where they live. The pellets include small particles in bigger packages, allowing them to sink to the ocean floor. This allows for the composition of the bottom sediment to closely resemble the particle content of the surface water. 19.
4.7 Discuss the present importance and the future prospects for the production of petroleum, sand and gravel, phosphorite, manganese nodules and crusts, and rare-earth elements.
a.
All of these are currently large deposits within the ocean. This provides additional resources to use in the future.
20.
4.7 What are gas hydrates, where are they found, and why are they important?
a.
Gas hydrates are composed of water and natural gas found in the deep ocean. They can easily be ignited when brought out of the water or to the surface. They can easily be used as another source of natural gas.