Oceanography Midterm

wrote the first book to deal exclusively with the ocean

Luigi Marsigli

The first great ocean exploration expeditions were

Charles Darwins voyage on the H.M.S. Beagle (1830s)
- Book Origin of Species

2nd great ocean exploration expedition

Challenger Expedition
- Laid the foundation of oceanography
Circumnavigated the globe

First Ocean Science dates back to

Aristotle

Oceanography is the science of the oceans including

Physics, chemistry, biology, and geology

Research vessels are important platforms to conduct oceanographic research; there are different types of vessels for different purposes

Small, large, ice cutter, drill ship

Attempt by Fridtjof Nansen to reach the geographical North Pole by harnessing the natural east-west current of the Arctic Ocean

Nansen's Fram Expedition

Passage between Greenland and Svalbard is known as

Fram Strait

Length is measured in

meters (m)

Temp is measured in

Kelvin (K)
- 0K \= absolute zero
Celsius (C)
- 1C \= 1.8K

Mass is measured in

Kg

Concentration is measured in

Moles
- Avogadro Constant

Two hypotheses for the origin of water on Earth are debated as:

1. From inside Earth -\> Volcanic outgassing
2. Introduced by meteoroid impacts

The basic structure of Earth consists of

Crust
mantle - Silicate rock, 3.3g
Core - Iron-rich

Oceanic crust is made of

basalt 3.0g

Continental crust is made of

Granite 2.7g

The crust and the uppermost mantle form the cold and strong

Lithosphere

Hot and plastic

Asthenosphere

The state of gravitational equilibrium between the lithosphere and the asthenosphere of the Earth such that lithospheric plates "float" at a given elevation depending on their thickness

Isostacy

Most of Earth's surface is elevated either a little above sea level or 2-6 km below sea level

Bimodal distribution

We map the ocean floor either through

Satellite Altimetry or multibeam sonar
(Ships and underwater vehicles)

Granite is less dense, but thicker than

basalt

Major oceanic areas are:

Atlantic Ocean, Pacific Ocean, Indian Ocean, Arctic Ocean, Southern Ocean

Important marginal seas include

Med Sea, Mexico Gulf, Caribbean Sea, North Sea, Persian Gulf, and South China Sea

Major depth zones of the seafloor consist of (from shallow to deep)

Cont shelf, cont slope, cont rise, ocean basin (abyssal plain), deep sea trenches

Continental Margins are either

Passive - broad flat shelves
Active - Narrow shelf adjacent to deep-sea trench

The deepest trench is the

Mariana Trench

At MOR new seafloor is formed through

Uprising hot mantle material at spreading zones of oceanic plates

Removes heat from Earth's interior

Mantle Convection

Any object immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object

Archimedes Principle

epipelagic zone

Sunlight zone

Mesopelagic zone

twilight zone- some sunlight penetrates but not enough for photosynthesis to occur (disphotic zone)

Bathypelagic zone

Midnight zone, no light at all

hadal zone

The trenches

Erosional incisions through shelf and slope that transport sediments from the rise out onto the abyssal plains

Submarine Canyons

Earth's longest continuous mountain chain

Mid Ocean Ridges

Keeping Isostacy in mind, why do mid-ocean ridges stand up so high above the ocean bottom?

The rising hot mantle material is less dense than the cooled crust around it

Used by scientists to build accurate models of natural phenomena

The scientific method
1. Observe
2. Generate
3. Test

Fundamental unifying theory which explains the shape of the Earth's surface

Plate Tectonics

Observations that lead to the development of the Plate Tectonic theory are:

Cont jigsaw puzzle, geologic features that line up across conts, distribution of earthquakes, magnetic orientation of seafloor rocks, thickness/age of ocean seds

Wegener's observations

1. Coastlines of the conts fit together
2. Many geologic features line up across the boundaries

What did Wegener hypothesize from his observations

The existence of continental drift

The point in Earth's interior where earthquake energy is released

Focus

The energy waves in an earthquake that moves outwards from the focus and make the ground quake

Seismic Waves

At trenches, Earthquakes get deeper with

Distance

What in the outer core generates Earth's magnetic field?

Convection

Dominantly \__ magnetic field

Dipolar

Magnetic poles \__ every 250k years

Reverse locations

Molten rocks erupts and cools into crystal form. Some crystals with iron in them are magnetic, they tend to line up With the Earths magnetic. A magnetometer will pick up a weak wild if the crystal magnets point the opposite direction from the Earth's field. It will pick up a strong field if the crystals point the same direction.

Dating rocks w/ magnetism

New oceanic lithosphere is generated at

Mid ocean ridges

Ancient oceanic lithosphere is consumed at

Deep-sea trenches (subduction zones)

They key to lithosphere recycling

Convection (heat transfer by moving fluid)

Three types of plate boundaries

divergent, convergent, transform

Divergent boundaries form

New seafloor at spreading zones (ex, Mid-Atl ridge)

One plate subduction under another plate

Convergent boundaries
1. Ocean-cont
2. Ocean-ocean
3. Cont-cont

two plates slide past each other horizontally

transform boundary

All today's conts were once united into one giant cont called

Pangea

Forms independent of tectonic plate boundaries and are fed by underlying mantle that is anomalously hot

Hotspots

Plate tectonics theory introduced by

Alfred Wegener

Where would you expect to find the thickest (oldest) sediment accumulation?

At passive continental margins

Observations often reveal limitations to the most well-established ideas, no measurement is perfect.

Scientific certainty
Formal uncertainty

Represents a hypothesis that has been confirmed by repeated independent experimental tests

Scientific Theory

Any particulate matter that ca be transported by fluid flow and deposited

Sediment

Different types of sediments

Terrigenous, biogenic, chemogenic, volcanogenic, cosmogenic

Sediment size is classified from smallest to largest as:
The smallest fraction is easily transported and travels the longest distance

1. Clay
2. Silt
3. Sand
4. Gravel

Continuous shower of mostly organic detritus falling from the sunlight layers of the water colum. Made up of a variety of mostly organic matter

Marine snow

Are more stable in shallow waters and dissolve below the CCD, because cold water dissolves more CO2, making it more corrosive for it.

Calcareous shells

More stable in deep ocean, where silicate concentrations in the water are high

Siliceous shells

Seafloor around continents are dominated by

Terrigeneous sediments

Red clay and chemogenic sediments are found at

Remove abyssal plains

Sediment accumulation on the seafloor depends on the

Age of oceanic plate and the sedimentation rate

When the sediment burden at cont margins is too high, slope failure can lead to

Submarine landslides and tsunamis

The study of the history of the oceans in the geologic past.

Palaeoceanography

Most sediment accumulate near

Continents

More CO2 can dissolve in cold water and make the water more acidic. Calcium carbonate tends to dissolve fastest in deeper water because it tends to be more

Acidic

Oozes are uncommon

Near continents and where there are few nutrients

Process whereby a mineral or sedimentary rock deposit is generated where it is found or observed

Authigenesis

The main constituents of deep sea sedimentation

Authigenic sediments

Wh do carbonate shells dissolve below the CCD?

Because the deep ocean is cold, enabling more CO2 to dissolve, which forms carbonic acid and dissolved carbonate

Found where no other sediments accumulate rapidly

Abyssal Clays

Evidence of past slides with sediment different from the layer below and above

Turbidities

Atoms consist of

Protons, neutrons, nucleus, and electrons

Protons are

Positively charged

Electrons are

negatively charged

Substances made up of chemically bonded atoms

Molecules

Consist of two of the same atoms

Diatomic molecules

Consist of different atoms

Polyatomic molecules

Share 1 electron

Single bond

In this bond, two atoms share electrons. If one atom pulls the electron closer to its center it gains a slightly more negative charge.

Covalent bonds

A covalent bond between two atoms where the electrons forming the bond are unequally distributed

Polar covalent bond

If the charges in a molecule are located at two ends, a \___ forms

Dipole

In this bond, valent electrons move from one atom to another. The atom that gives away electrons becomes positively charged (\___), the one that receives electrons become negatively charged.(\____)

Ionic bond
Cation
Anion

The amount of heat needed to raise the systems temp by one degree

Heat capacity

Has a very high heat capacity, takes a lot of energy to heat it up compared to other systems

Water

Plays an important role thanks to their high heat capacity, in regulating our climate

Oceans

Water freezes/melts at \__ and boils/condenses at __

0 degrees, 100 degrees

The density of liquid water changes with

Temp, nonlinear

Has a lower density than liquid water

Ice

A way to transport heat through the movement of liquids. When heated, water loses density and rises, when cooled it increases its density and sinks

Thermal convection

Thermal convention plays an important role in

Ocean circulation