Oceanography 4

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

high latitudes; equatorial upwelling zones

Two common types of chemical compounds found in biogenous sediments are __________ and __________.

calcium carbonate; silica

What is calcareous ooze?

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

As a whole, the pH of surface waters of the ocean is slightly __________.

alkaline

What is the calcite compensation depth, or CCD?

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

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.

Carbon dioxide (CO2) combines with water (H2O) to form __________.

Carbonic acid (H2CO3)

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.

Sediments derived from the remains of the hard parts of once-living organisms are called __________ sediments.

biogenous

The depth at which calcite dissolves rapidly in the ocean is called the __________.

calcite compensation depth or CCD

Calcite-secreting organisms such as __________ and __________ live in the ocean's sunlit surface waters and form the basis of most marine food webs.

coccolithophores; foraminifers

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

The two major types of microscopic, planktonic organisms that produce siliceous oozes are __________ and __________.

diatoms; radiolarians

The pH scale is a measure of the __________ ion concentration of a solution.

hydrogen