Download Oceanography Questions for Test 1

Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
ASU Student Number(last four digits):___________________
Please note your student number (last four digits is ok) on the first page. Read questions
carefully and be concise. Numbers in brackets are total points, which sum up to 130.
1. (5) Islands in the Hawaiian Island chain (mark all that apply)
Are made of granitic rock
Are part of an island arc created due to subduction at trenches
Are hot spot volcanoes located on the Pacific Plate
Are increasing in age from north to south
Will eventually subduct in the Aleutian trench
2. (6) Hydrothermal vents (mark all that apply):
Were discovered during the Challenger expedition
Have chimneys made of metal sulfides precipitated from seawater
Are located in the deep sea at spreading centers
Are void of life because of the scalding water that emanates from the rocks
Provide ample source of sodium chloride to the ambient water
Host a flourishing community of animals that feed on chemosynthetic
bacteria
3. (5) From the surface inward, the classification of the Earth’s layers based on physical
properties is:
asthenosphere, lithosphere, lower mantle, core
crust, mantle, outer core, inner core
lithosphere, asthenosphere, lower mantle, outer core, inner core
inner core, outer core, mantle, crust
crust, lithosphere, asthenosphere, upper mantle, lower mantle, core
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Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
4. (5) The three major types of plate boundaries are:
normal, reverse and thrust
convergent, divergent and transform
oceanic, continental and transform
lithosphere, asthenosphere and mantle
rise, slope and shelf
5. (4) The Deep-Sea Drilling Project confirmed that the youngest ocean crust is found
at axes of ocean ridges
at random locations across the sea-floor
relatively close to continental margins
within deep-sea trenches
6. (5) Submarine Canyons were most likely formed by
Deposition of terrestrial sediment
Earthquake activity
Erosion by major rivers in the past
Erosion by turbidity currents
Scouring by glaciers during the last ice-age
7. (6) Which of the following organism groups contribute to siliceous oozes (S) or
carbonaceous oozes (C)? Write the letter (S) or (C) where appropriate.
Diatoms S
Coccolithophorids C
dinosaurs
radiolarians S
martian meteorites
pteropods C
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Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
8. (5) All of these are hydrogenous sediment except
Evaporites
Halites
Manganese nodules
Phosphates
Stromatolites
9. (5) The correct order of marine provinces from the coast to the mid-ocean
Abyssal plain, rise, slope, shelf
Abyssal plain, shelf, slope, rise
Rise, abyssal plain, slope, shelf
Shelf, slope, rise, abyssal plain
Slope, rise, shelf, abyssal plain
10. (5) Which ocean is currently getting smaller in size?
Antarctic
Arctic
Atlantic
Indian
Pacific
11. (6) Which of these processes add ions to the oceans (mark the ones that apply):
Volcanic eruptions
Sea spray
Rivers
Hydrothermal vents
Formation of evaporites
Subduction
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Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
12. (5) When photosynthesis was ‘invented’ by unicellular organisms, Earth’s
environment changed profoundly, with great consequences for life and its
evolution. Name 3 major changes, and 2 dates that bracket the events.
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Oxygen revolution (about 2.5 Ga ago): steady build-up of oxygen
released by oxygenic photosynthesis oxygenates the initially reducing
atmosphere and ocean
Dying of many anaerobic life forms
In situ synthesis of organic molecules ceases due to lack of short
wavelength UV radiation
Formation of ozone layer prevents penetration of harmful UV
radiation
Evolution of heterotrophic multicellular life able to use oxygen to
respire organics produced by photosynthesizers.
Colonization of land (460 Ma)
13. (5) Name ONE oceanographic expedition/ship and briefly state its major contribution
to oceanographic science. Also include the name of a leading figure and
approximately when (half of century is sufficient) the expedition took place.
HMS Endeavour, OR Resolution, Adventure; James Cook; second half of 18 th century;
charting of Pacific and previously unknown land (e.g. west coast of North America),
discovery of Hawaii, oceanographic sampling and observations
OR
HMS Beagle; Charles Darwin; first half of 19th century; discovery of the structure of coral
reefs, observations of birds on Galapagos was the ground work for his work ‘On the Origin
of Species’
OR
HMS Challenger; Thomson/Murray; second half of 19 th century; first sailing expedition
devoted to marine science, term ‘oceanography’ was coined; extensive sampling of deep-sea
floor; extensive oceanographic work related to distribution of sediments, ocean currents etc.
OR
First Meteor expedition; first half of 20th century; Georg Wüst chief scientist; echo sounding
of South Atlantic, discovery of mid-Atlantic ridge
OR
Glomar Challenger; second half of 20th century; International Deep Sea Drilling Project;
confirmation of sea-floor spreading
OR
Fram, end of 19th century, Fritjof Nansen, discovered that there was no continent beneath
the Arctic Ocean
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Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
14. (4) Satellites have become increasingly important for oceanography during the last
decades. Name two examples of satellites you have heard about in class and
which parameter/process is measured.
Ocean color satellites (e.g., CZCS, SeaWIFS, MODIS), phytoplankton biomass, primary
production
Weather satellites: Prediction of hurricanes
Radar satellites (e.g. TOPEX/Poseidon) Sea surface height (Bathymetry, wave height,
currents)
Temperature satellites (e.g. AVHRR) Sea surface temperature
15. (9) A rich philanthropist, who does not believe in the concept of plate tectonics, offers
you unlimited research funds, in addition to a generous compensation, if you can
provide him first-hand conclusive proof of continental drift or seafloor spreading.
Design a research program (ship-, land- or space based) to illustrate three
convincing lines of evidence for plate tectonics.
You could design an oceanographic research cruise to map the midocean ridges by any
bathymetric echosounding technique. You could then drag a magnetometer perpendicular
to the ridge and determine magnetic anomalies, map these and show that magnetic
anomalies run parallel to the ridge. You could charter the Joides Resolution, bore into the
ocean crust underneath sediments and date the rock samples; you would see that nowhere
was the ocean floor older than about 180 Mio yrs, whereas the age of the continents is about
3.8 Ga. Take a field trip to all of the Hawaiian Islands and show by rock dating that they
become younger as you go south, indicating that the Pacific plate is moving across a Hot
Spot. You could attach satellite emitters on any fixed location on continental plates across
the Atlantic and analyze the relative movement of the plates. ETC
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Oceanography GLG 394 Neuer/Nunez –Fall2005
Midterm Exam
16. (10) A schematic of the continental margin.
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1
5
2
3
6
a. (6) Name features 1-6.
1. Continental shelf
2.Continenatl slope
3.Continental rise
4.Submarine Canyons
5. Deep-Sea fans
6. Graded bedding
b. (4) Would you expect to find biogenic ooze in location (1)? Explain your answer.
No, because the supply of lithogenous material from rivers, deserts, glaciers (depending
where you are) typically dilutes any biogenic contribution to sediment formation (below
the critical 30%).
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Oceanography GLG 394 Neuer/Nunez –Fall2005
Midterm Exam
17. (14) In the following image, A-B is a transect across the tropical North Atlantic, C-D
a transect from eastern Australia to South America across the Pacific.
1
2
4
5
3
a. (10) Name the geological features that are marked from 1-5. Where appropriate,
state the type of plate boundary.
1. continental margin (I also accepted continental slope or shelf)
2. mid-ocean ridge (Mid Atlantic Ridge), divergent plate boundary
3. abyssal plain
4. mid-ocean ridge (East Pacific Rise), divergent plate boundary
5. ocean trench, convergent plate boundary
b. (4) In transect A-B, where do you expect the greatest sediment thickness? Why?
(two reasons)
At (1). Sediment thickness increases away from the mid Atlantic ridge towards the
continental margin (rise) because a) age of seafloor increases and seafloor has
accumulated more sediment and b) continental shelf/slope is a source of sediment for the
continental rise and abyssal plain.
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Midterm Exam
Oceanography GLG 394 Neuer/Nunez –Fall2005
18. (9) You are on a sedimentology cruise that started in San Diego and you are heading
south to Antarctica. As you head south the ship’s echo sounder record shows
that water depth decreases and you realize that you are approaching the East
Pacific Rise. You are taking surface sediment samples with a corer at stations
along the way, and to your surprise, the composition of the surface sediment
changes. Then you remember your recent ASU oceanography class and start
thinking. You remember why there are different types of surface sediment as
you cross the equator. Name and explain them. You can sketch a diagram if
that helps you.
North of the equator, the sea-floor is below the CCD and calcium carbonate dissolves before
it reaches the sea floor; productivity in the overlying water is low so that no other ooze
former is abundant enough to form an ooze, the sediment is abyssal clay
Eq. Pacific: High levels of productivity in the upper water column and abundance of
radiolaria give rise to radiolaria (siliceous) oozes. Also, the equator is slightly below the
calcium carbonate dissolution depth (CCD) so that calcium carbonate (which is also
produced in the upper water abundantly) does not accumulate.
South of the equator: Ocean floor is above the CCD as you move up the slope of the East
Pacific Rise and enough calcium carbonate tests arrive to form calcareous ooze.
19. (5) Abyssal clays are often underlain by calcareous ooze, even below the calcium
carbonate dissolution depth. Why?
Initially, mid ocean ridges accumulate calcareous sediments as they are above the CCD
(mixed with abyssal clay, but calcareous sediment accumulates in a proportion >30% which
classifies it as calcareous ooze). As oceanic lithosphere moves away from spreading centers,
it cools, becomes denser and subsides. It will eventually sink below the CCD and start
accumulating mainly abyssal clay; thus older calcareous ooze may be found below younger
abyssal clay.
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Oceanography GLG 394 Neuer/Nunez –Fall2005
Midterm Exam
20. (12) The following questions refer to the T-S graph depicted below.
a. (1) Which parameter is depicted by the curves ?
Density
b. (1) How are those curves called?
Isopycnals
c. (1) What does the arrow in the graph indicate?
Increase in Density
d. (4) Draw values on the axes corresponding approximately to the natural
range of open ocean seawater
- See figure.
e. (3) Identify the approximate density of water parcels of the following T-S
characteristics by drawing them into your T-S graph:
i. T: 25 C, S: 37
ii. T: 10 C, S: 36
iii. T: 0 C, S: 34
- See figure.
f. (2) Knowing that the denser water sits below the less dense water in a
stable water column, order the parcels from lighter to heavier.
Lightest: i  iii  ii :Heaviest
i
Isopycnals
ii
iii
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