Oceanography Chapter 4 Flashcards

Questions and Answers

What is calcareous ooze?

a fine-grained, deep ocean sediment containing the skeletal remains of calcite-secreting microbes

What is the calcite compensation depth, or CCD?

the ocean depth below which calcite is unstable and will dissolve quickly

What three steps are required for calcareous ooze to exist below the CCD?

deposition of calcite shells above the CCD, cover of these shells by a non-calcareous material, and movement of the sea floor over millions of years

What would happen if the depth of the CCD were above the top of the mid-ocean ridge?

Calcareous ooze would not be found below the CCD. Signup and view all the answers

Sediments derived from the remains of once living organisms are called?

Biogenous sediments Signup and view all the answers

Two common types of chemical compounds found in biogenous sediments are?

Calcium carbonate and silica Signup and view all the answers

The two major types of microscopic planktonic organisms that produce siliceous oozes are?

Diatoms and radiolarians Signup and view all the answers

How does siliceous ooze accumulate on the seafloor if silica-based residues are dissolved slowly at all depths?

Silica tests accumulate faster than seawater can dissolve them. Signup and view all the answers

Siliceous ooze is particularly abundant on the seafloor at and at .

high latitudes; equatorial upwelling zones Signup and view all the answers

What is the approximate depth of the calcium compensation depth (CCD) in the ocean?

3 miles, 4.5 km Signup and view all the answers

Forams, which are composed of calcium carbonate, above the CCD and below the CCD.

do not dissolve; dissolve Signup and view all the answers

Diatomaceous earth, which is composed of silica, above the CCD and below the CCD.

does not dissolve; does not dissolve Signup and view all the answers

Why does calcareous material dissolve below the CCD?

Below the CCD, weak acid is formed, which dissolves calcareous material. Signup and view all the answers

Which of the following statements about the CCD is correct?

Below the CCD, physical conditions cause calcium carbonate to dissolve Signup and view all the answers

Where is calcareous ooze most likely to be found in surface sediments in the ocean?

Relatively shallow areas with warm surface water Signup and view all the answers

Which of the following explains why calcareous ooze is sometimes found below the CCD?

Calcareous ooze can be deposited above the CCD and covered with other sediment which protects it as the tectonic plate moves it into deeper water. Signup and view all the answers

The tests from which of the following organisms will dissolve below the CCD?

Foraminifera and coccolithophores Signup and view all the answers

What is calcareous ooze composed of?

At least 30% the remains of calcareous organisms Signup and view all the answers

Where do calcareous oozes exist on the sea floor?

Underneath areas where calcareous organisms live but above the CCD Signup and view all the answers

What conditions exist below the CCD?

High acidity, cold temp, high carbon dioxide concentration Signup and view all the answers

Which setting would calcareous ooze be most likely to form?

On the crest of a seamount under warm surface water Signup and view all the answers

Study Notes

Calcareous Ooze

Calcareous ooze is fine-grained sediment in deep oceans, composed of skeletal remains from calcite-secreting microbes.
It contains at least 30% remains of calcareous organisms.

Calcite Compensation Depth (CCD)

The CCD is the ocean depth where calcite becomes unstable and dissolves quickly.
Approximately 3 miles (4.5 km) deep, influencing calcareous sediment distribution.

Formation of Calcareous Ooze

For calcareous ooze to exist below the CCD, three steps are essential:
- Deposition of calcite shells above the CCD.
- Covering of these shells by non-calcareous material.
- Movement of the seafloor over millions of years.

Impact of Mid-Ocean Ridge

If the CCD rises above the top of the mid-ocean ridge, calcareous ooze would not be found below the CCD.

Biogenous Sediments

Sediments from previously living organisms are termed biogenous sediments.
Key chemical compounds in biogenous sediments include calcium carbonate and silica.

Siliceous Oozes

Siliceous oozes arise from diatoms and radiolarians.
Silica-based residues accumulate faster than seawater can dissolve them, ensuring accumulation on the seafloor.

Locations of Abundance

Siliceous ooze is prevalent at high latitudes and equatorial upwelling zones.

Dissolution Characteristics

Foraminifera do not dissolve above the CCD but dissolve below it.
Diatomaceous earth does not dissolve at any depth.
Calcareous material dissolves below the CCD due to weak acid formation from increased carbon dioxide.

Conditions Below CCD

Below the CCD, conditions include high acidity, cold temperatures, and elevated carbon dioxide concentrations.

Calcareous Ooze Locations

Calcareous oozes generally exist in relatively shallow areas with warm surface waters.
They are often found beneath regions where calcareous organisms thrive, but above the CCD.

Seamount Formation

Calcareous ooze is likely to form on the crest of seamounts where warm surface water is present, facilitating organism proliferation.

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Description

Explore key concepts from Chapter 4 of Oceanography with these flashcards. This quiz covers important terms such as calcareous ooze and calcite compensation depth. Test your understanding of deep ocean sediments and their characteristics.