Week 1: Intro + Mari. Chem

Question 1

Times series graphs show

Answer 1

Change

Question 2

In times series x and y axis show

Answer 2

x = Which end is older
y = What we are measuring

Question 3

Diagram that shows time and space scales

Answer 3

Stommel diagram

Question 4

Geologists in the ocean wonder

Answer 4

1. What was the system like in the past
2. How different was the world back in time
3. How do today’s changes fit into that context
4. Could that history be affecting whats happening today
5. Are we ignoring the past at our peril

Question 5

Ga =
Ma =
Ka =

Answer 5

Ga = Billion years = 10^9y
Ma = Million years = 10^6y
Ka = Thousand years = 10^3y

Question 6

The Four phases of earth and when they were

Answer 6

1. Hadean earth (4.5-3.8 Ga)
2. Archean earth (3.8-2.5 Ga)
3. Proterozoic earth (2.5-0.5 Ga)
4. Phanerozoic earth (542 ma - Present)

Question 7

Hadean earth characteristics

Answer 7

1. New molten planet too hot for liquid water
2. Source of water may have been frozen comets bombarding the plant
3. Early water would have escaped into space
4. The moon grazed the earth (about 4.4 Ga) and coalesced in orbit (thus ready to start making tides) - huge heat event
5. As the earth grew larger and cooled somewhat, an atmosphere, and water, was retained
6. By about 4.0 Ga, the surface was solid enough to have broken into plates, and there was possibly a water ocean

Question 8

Archean earth characteristics

Answer 8

1. Rain, centuries of rain, and eventually the ocean
2. Almost no O2 in atmosphere or ocean (to begin with)
3. Ocean full of dissolved iron
4. Atmosphere dominated by methane (Ch4) and ethane (C2H6)
5. Methane is an effective greenhouse gas, that may have helped the earth stay warm at a time of “faint young sun” - 70-80% as luminous as today
6. Simple unicellular life: stromatolites 3.5 Ga
7. Continents formed, and some evidence of life on land (3.2 Ga)

Question 9

Proterozoic earth characteristics

Answer 9

1. Rising O2 levels at the GOE (great oxidation event) would have replaced the methane, and the earth entered its first “snowball earth” glaciation (about 2.1 Ga)
2. A very tectonically active time
3. Soft-bodied complex animals (ediacaran fauna)

Question 10

Phanerozoic earth characteristics

Answer 10

1. Means “visible life” = fossils
2. Onset of biomineralization
3. For the first time, we can find seafloor rocks (previously subducted) and direct evidence of ocean conditions

Question 11

Three eras of phanerozoic earth

Answer 11

1. Paleozoic (inverts, fish, amphibians)
2. Mesozoic (reptiles, some mammals)
3. Cenozoic (mammals, birds)

Question 12

Salinity

Answer 12

Total dissolved salts in water,
About 85% is NACL

Question 13

Average PSU of the ocean

Answer 13

35 PSU

Question 14

Percentage of nitrogen and oxygen in the air

Answer 14

Nitrogen = 78%
Oxygen = 21%

Question 15

Two main oxygenation events and the time of their happening

Answer 15

1. Great oxygenation event (2.4 Ga)
2. Neoproterozoic oxygenation event (600 Ma)

Question 16

Measure of units of sun radiation

Answer 16

W/m^2 (watt per square inch)

Question 17

Sun radiation on a surface affected by

Answer 17

Angle, distance (season, orbit), sun itself (sunspots), time

Question 18

On average, the earths atmosphere as a whole recieves

Answer 18

340 W/m^2 per year

Question 19

How long ago was the suns ignition

Answer 19

The same time as earths creation (4.57 Ga)

Question 20

At ignition, the sun was ___ percent less bright

Answer 20

30%

Question 21

Cambrian vs present seawater temperature

Answer 21

Cambrian = 25 degrees
Present = 17 degrees

Question 22

Cambrian vs present seawater saltiness

Answer 22

Cambrian = 40 ppt salt
Present = 34 ppt salt

Question 23

Cambrian vs present oxygen in atmosphere

Answer 23

Cambrian = 18% of Atm
Present = 21% of Atm

Question 24

Cambrian vs present sun brightness

Answer 24

Cambrian = 95% of todays brightness = 320 W/m^2
Present = 340 W/m^2

Question 25

Cambrian vs present CO2 in atmosphere

Answer 25

Cambrian = 300 ppm Present = 415 ppm and climbing

Question 26

Cambrian vs present seawater PH

Answer 26

Cambrian = 7.2 Present = 8.1

Question 27

Cambrian vs present Mg:Ca ratio in ocean

Answer 27

Cambrian = 1 Present = 5

Question 28

For much of earths history, the ocean was:

Answer 28

1. Much hotter and cooling 2. Lacking in oxygen, with sudden dramatic increases 3. Receiving ever-brighter sunlight 4. Increasing in salinity, but with a lot of variation 5. Increasing gradually in PH 6. Atmospheric CO2 and ocean PH tracked temperature trends 7. Oscillating between high and low Mg:Ca ratios, with consequent mineralogical variation in shells and other deposits

Question 29

Long term trends/curves have

Answer 29

Low resolution, meaning the older the less known or certain