Heat & Deep Ocean Circulation
Why is it colder at the poles than at the equator?
Why don’t the oceans evaporate in the equator and freeze over in the poles?
Discuss the heat budget of the earth?
What drives ocean circulation? Explain.
Generally, the colder things get the denser. Why, then, does ice float in the oceans.
Explain the ramifications of an ocean where the ice froze from the bottom to the surface.
What are salts? What are the principle salts and where did they come from?
How are salts removed from the oceans?
The Red Sea shows salinities of up to 44 0/00. How do you explain these high salinities?
If the water freezes at 0oC, how do you explain ocean water that is -2oC.
How does density in water change as the water cools from 20oC to -2oC.
Where the oceans always salty? Why or why not?
In comparison, ocean water is depleted in Si and Ca. Why?
Which two principle factors influence the salinity of ocean water?
Of the 2 listed above, which is the most important? How can you demonstrate this?
How does precipitation and salinity vary with latitude?
Explain why the oceans are stratified. Use a diagram.
The Pacific is not as well stratified as the Atlantic. Why?
The residence time for Cl is 6 my, for Na 4 my and Fe 100yrs. What accounts for the differences?
Make a sketch of the ocean thermohaline circulation?
In regards to age, how does the Pacific deep water compare to the Atlantic?
What are the ramifications of the above answer to to organic matter concentration, CO2 &O2 concentration,
acidity, and depth to CCD?
What is upwelling. And what causes it
Why is upwelling important
Surface Circulation
How do convection cells develop.
Explain why wind\water is deflected to the right in the Northern Hemisphere and to the left in the Southern
Hemisphere
Note the difference in the development of convection cells in the slides showing a rotating and non-rotating
earth.
 I want you to be able to explain why the convection cells are at an angle. .
 Use the above diagram to explain how the ocean circulation gyres develop in both the Northern and
Southern Hemisphere
England is further north than areas of Nova Scotia yet its climate is not as extreme. Why?
Which currents (location e.g. western boundary currents) are
 Warm water
 Cold water
 Flow faster
 Flow slower
 Narrower and better defined
 Wider and more defuse
Wind blowing over the surface of the ocean in the northern hemisphere will deflect water to the right how
many degrees?
What is Eckman Transport?
Along the Peruvian margin, which wind, northerly or southerly, will promote upwelling or downwelling
Explain why upwelling occurs in the equatorial region.
The California Current is impacted by changes in climate such as El Nino/La Nina events. Howmight these
climatic changes manifest themselves in the sediment? Think of upwelling and temperature of waters.
Sediments
Examine the slide showing sediment thickness.
Where do the thinnest and thickest sediments occur and why?
What is the difference between the Atlantic and Pacific and why?
Examine the slide showing accumulation rates?
How long would it take to accumulate 1 meter on the shelf, Fraser River,and in the deepest regions of
the ocean where clays accumulate?
Carbonate sediments are lithogenous, biogenous, hydrogenous or cosmogenous?
How do lithogenous/terrigenous sediments enter the ocean basins?
Clays are light and would take an great amount of time to sink to the seafloor. Why do clays settle to the
seafloor in a matter of days?
Would you expect submarine fans to be better developed in the Atlantic or Pacific
Make a sketch showing the structure of a turbidite.
How would pelagic sediments differ from neritic sediments?
What are the principle components of siliceous and carbonate oozes?
Explain the diagram showing sediment distribution.
T/F Ocean waters are undersaturated with respect of silica?
T/F Ocean surface waters are more depleted in silica than deeper waters. Why?
Define the lysocline
Define the CCD.
What causes the CCD?
Can carbonate sediments be found beneath the CCD. Explain
Explain the relationship between oxygen, carbon dioxide, photosynthesis, pH, organic matter decay,
respiration, the photic zone and the acidity of ocean waters.
Write the formula for carbonic acid when water mixes with CO2
Why are red clays red?
As a scientist on an ocean cruise you pull up a core from a 6000 meter depth in the ocean. The core contains a
foraminiferal ooze layer showing an erosional contact with the underlying sediment, a graded base followed
upwards in succession by parallel lamination, ripples, and laminations in fine grained sediments
What is the origin of layer.
Was it deposited above or below the CCD?
Why is it preserved?
You decide to drill another core in the central Pacific in which you encounter laminated coccolithophore ooze
at a depth of 6000 m depth and which shows no evidence of redeposition. The ooze is overlain and underlain
by red clay containing partially dissolved diatoms, radiolarians and sponge spicules. Explain your
observations.
Would you expect the CCD to be higher or lower beneath a high productivity area? Why?
Why then does the CCD become shallower towards the margins of continents and the artic and Antarctic
regions where productivity increases and lower beneath the high productivity equatorial region?
Why does upwelling occur in the equatorial region?
Explain why upwelling occurs in the spring and summer months and downwelling in winter months off the
coast of California?
How will this spring and summer upwelling and winter downwelling manifests themselves in the sediments
deposited in the California basins.
Examine the slide showing the topography of the CCD, how does the topography change from the Atlantic to
the Pacific. Why?
Examine the slide showing ridge stratigraphy, how does it develop?
Which dissolves at shallower depths, aragonite or calcite? Why?
Give two reasons why upwelling deep water would release more CO2 to the atmosphere
Paleoceanography
How do present day CO2 levels compare to the past 400000-600000 years?
Why are the CO2 levels elevated today?
How do we know what the CO2 level were in past if humans were not around to measure them?
What are the counterarguments to an anthropogenic cause for climate change?
What are the counterarguments to climate change being solely caused by natural processes such as variations
in solar radiation due to the eccentricity of earth’s orbit, its precession and obliquity?
Which other causes exist for natural climate change?
Explain what happens to the 18O/16O ratios during an interglacial period and why?
Explain what happens to the 18O/16O ratios during a glacial period and why?
Under what conditions will planktonic foraminera have high 18O/16O ratios?
A foraminifer test has a 180 value of -1% relative to VSMOW. Through reference to the formula for
calculating 18O, explain whether it contains more of less 160 than VSMOW.
What is the meaning of a 18O value of 0%.
About 80% of the ocean floor is below the CCD, what does this mean about using foraminifera as climate
indicators and for isotope correlation?
Would you expect the Atlantic to have higher 13C/12C ratios than the Pacific. Why or Why not?
Note the porous diatom frustrule. It is light and would take a long time to settle to the seafloor. How then
does it reach the seafloor in a day or so.
Also why arent’ there diatoms scattered throughout the whole ocean floor by ocean currents?
Which factors control the 13C/12C ratios? Explain.
Explain the graph showing the Paleocene and Eocene delta 18O and delta 13C trends.
For the foraminifera, diatoms, radiolaria, coccolithophores distinguish between phytoplankton or zooplankton,
SiO2 or CaCO3 composition, and when they first appear in the rock record.
Why would Quaternary and late Tertiary foraminifera be more suited for reliable ocean sediment correlations
than those found ,say, in the Cretaceous or Paleocene?
Why would you expect benthic diatoms to be restricted to shallow waters?
In a high productivity region with diatoms and radiolaria, which would you expect to be more abundant and
why/
Which would you expect to have more robust tests, benthic or planktic foraminifera, radiolarian, and diatoms?
Why.
Magneto and Seismic Stratigraphy
What are the limitations to Magneto and Seismic Stratigraphy.
How are recent overprinting of the older magnetic signature removed from the sample.
Why are changes in polarity considered instantaneous events and how is this useful for correlation purposes?
Why is the paleomagnetic record less dependable for older rocks?
You recover two cores drilled in widely separated areas of the pacific basin and you determine the magnetic
patterns. What must you do to assure accurate correlations?
How was the sea level curve developed?
Why must we be cautious about the application of the sea level curve.
Reading (
Which is the most abundant sediment type/
What are the 2 most important processes controlling the composition of biogenous oozes?
In Figure 8.4 what controls whether a calcareous or siliceous ooze will form?
Why is the burial of organic matter enhances along the continental margins?
What produces the red color of deep sea clays.
In section 8.4.3, what would cause a change from kaolinte rich lay to chorite rich clay in a core.
The greatest depth of the CCD is 5.5 m in the Northern Atlantic. Why?
Why is there a CCD/
How will the ocean react to the increased CO2 we are putting in the atmosphere and how will it impact
sediment accumulation?
What is the origin of deep sea chert?
Paleoceanography
What are ocean anoxic events.
How would you go about identifying these in ocean sediments and rocks on land?
How do deep ocean water become oxygenated?
Why is the Black Sea & the OMZ important to determining the origin of OAEs
Describe the Black Sea setting and why it is anoxic.
How do OMZs develop and where ate they mostly found?
Draw an oxygen, temperature, and nutrient profile through the OMZ.
You drill a core through sediments developed as a result of an OAE. Would O18values increase or decrease?
O13? Why?
Whether you ascribe the origin of OAEs to the Black Sea or OMZ models, carries implications about ocean
temperatures, upwelling and productivity, and ocean circulation. What are these implications?
What conditions led to the Paleocene\Eocene thermal maximum.
What role might volcanic eruptions play in the generation of anoxic\low oxygen events?