Fe, Mg, Si, O plus Na, Ca, Al, and more Si, O (which is ocean crust!)
Large ions incompatible with olivine and pyroxene structure that go into the melt:
K, Th, Ba, Rb, La
How to get the mantle to melt:
Shallow, thick ridges are formed over ____ spots; deep, thin ridges are formed over______ spots.
More melting at a higher temperature correlates to low _____ and ______ depth,
low Na; shallow depth
How is continental crust formed?
Partially melted ocean crust (get even higher concentrations of large ions that don’t belong in olivine and pyroxene, which creates pink feldspar)
Ocean crust is ______, while continental crust is ______.
Large ion concentration would be highest in ______ crust, then _______ crust, then the _______.
continental; oceanic; mantle
Large ion concentrations are higher in _____ oceanic crust forming over _____ spots.
thin; cool (large ions are not happy in the mantle so they want to go into the melt ,so the higher the temperature, the more that melts, and the lower ion concentration is)
Most abundant elements in universe:
Most abundant elements on Earth:
O, Mg, Si, Fe
Most abundant elements in life:
C, H, O, N, P, S
Most abundant elements in atmosphere:
Gases are more likely to escape in a ______ atmosphere.
Escape velocity is _____ for smaller planets.
______ gases are more likely to escape.
_____ planets are better able to retain an atmosphere.
Origin of ocean and atmosphere:
-Volatiles trapped in solid minerals; released during core/mantle -Late arriving carbonaceous chondrites (ordinary chondrites contain enough water to fill four oceans) -Late arriving comets
_____ isotopes indicate that much of the early atmosphere may have been lost to space when H2O was steam
_____ molecules have a higher average speed than _____ molecules.
Most of the carbon on Earth is in ________.
What helps keep the atmosphere’s oxygen content within a narrow range over geologic time?
– At high oxygen levels, organic matter spontaneously combust -At low oxygen levels, burial of organic carbon in the ocean will increase. -At high oxygen levels, burial of organic carbon in the ocean will decrease.
Long-term fluxes of carbon to and from silicate rock reservoir provide a negative feedback that stabilizes earth’s climate because
increased temperatures lead to increased weathering rates
The faint young sun paradox is resolved because
early earth was likely to have more greenhouses gases in the atmosphere.
A self sustained chemical system capable of self0replication and evolution.
Why is carbon important to life?
-Has 4 electrons missing from outer shell, which allows for reactions that allow energy flow and storage -Can form molecules that are solid, liquid, and gas at the temperatures of liquid water
Built amino acids. Proved that it would take a specialized environment (deep sea vent) to create them on Earth.
Cell membranes consist of a ____ bi-layer.
To build nucleic acids, a _______ can help concentrate ingredients.
What is easy to make in the lab from inorganic chemicals?
First type of life t get energy from sunlight (photosynthetic):
cyanobacteria (blue-green algae)
Types of rocks that cool from melt
Type of rocks that are weathered particles
Type of rocks that are deformed at high temperatures and pressure
Organic matter has low_____/______ levels.
The presence of life makes the ratio of 13C/12C in carbonate rocks higher than the ratio in bulk earth because organisms:
preferentially take up the heavier isotope (13C)
What fossil evidence do we have of earliest life?
Cells- 3.5 bya -Stromatolites- 3.5 by a
What chemical evidence do we have of earliest life?
Banded iron formations appear at 3.5 bya
_________ _________ _________ required anoxic ocean and atmosphere (so Fe can dissolve in seawater) and O2 gas in some isolated environments (to precipitate Fe oxides, Fe2O3)
Banded iron formations
Controls on atmospheric oxygen:
-process which produce oxygen (photosynthesis) -processes which destroy oxygen (consumption by oxidation of minerals/volcanic gases/organic material)
3.5-2 bya: All oxygen produced by photosynthesis is consumed by oxidation of minerals
All oxygen produced by photosynthesis is consumed by oxidation of minerals
Minerals at earth’s surface are saturated with oxygen and O2 builds up in atmosphere (evidence: red beds are rocks with oxidized iron minerals) And eucaryotic cells develop
0.6 by a:
final rise to today’s oxygen levels. first animals appear.
Why does the presence of banded iron formations between 3.5 and 2 bya require the presence of life in the ocean?
Because iron precipitates from seawater in the presence of oxygen gas
Why does the presence of BIF require an oxygen poor atmosphere?
Because iron dissolves in seawater in the absence of oxygen
What supports the idea that O2 gas started accumulating in the atmosphere after about 2 bya?
-BIF no longer form after 2 bya -Redbeds appear after about 2 bya -Eucaryotic cells appear at about 2 bya
Objects with lower temperatures emit electromagnetic radiation with _______ wavelengths than objects with higher temperatures.
An object with a radius twice the size of another object will emit energy ______ times as fast as the other object.
4. (radius squared; bigger objects emit more energy)
The rate at which energy emitted by the sun/area over which this energy is spread
Flux ________ with distance from the sun.
Solar radiation is _______ radiation, while infrared Earth radiation is _________ radiation.
Energy absorbed by the earth is the ______ at the distance of the Earth’s orbit x cross section of the Earth
Incoming energy from the sun is determined by ________ parameters and _______ of the sun.
orbital parameters and temperature of the sun
The temperature at the surface of the earth will be reached such that _______ in= ________ out.
A planet that is 5 times as far as another planet from the sun absorbs energy from the sun __________ times as fast as the other planet.
1/25 (1/distance squared)
A planet that is 5 times as far as another planet from the sun emits energy back to space __________ times as fast as the other planet.
1/25 (1/distance squared)
Reflectivity of the sun on earth
What contributes to albedo?
Clouds, ice, snow, aerosols, volcanic SO2
When outgoing infrared radiation is observed by the atmosphere and re-radiated both out to space and back down to the ground
Popular greenhouse gases
Water vapor (most important), CO2 (rarer, but effective at trapping radiation), methane, N2O, ozone
The earth’s surface is warmer than earth’s temperature as seen from space because
the energy emitted from earth’s surface must balance incomings shortwave radiation from the sun and incoming long wave radiation from the atmosphere (greenhouse effect)
Two ways to change earth’s surface temperature:
1) Change energy absorbed by sun 2) Change amount of greenhouse gases
Process in which perturbation causes system to travel further away from initial state
What stabilizes earth’s climate?
Long term CO2 regulation by weathering and volcanism
What removes CO2 from the atmosphere?
1) Chemical weathering 2) Plants and animals that form hard shells
What puts CO2 in the atmosphere?
1) Volcanism (when shells made of carbon are subducted, the carbon is released through volcanoes. 2) CO2 enters atmosphere faster when plate tectonics move faster
CO2 is removed faster from the atmosphere when _______ on continents is higher.
Early in earth’s history, there were probably more greenhouse gases (methane) that kept a role in keeping the earth warm
Faint young sun paradox
The high ratio f 2H/H in Venus’ atmosphere tells us that:
much of the water escaped as steam, which is why carbonates cannot form on Venus