EOS 120 MID 1

Radiogenic heat - the radio active decay of unstable isotopes.

Uranium^238&235   --------------> Lead

Potasium⁴⁰ --------------------> Argon

Thorium²³²--------------------> Lead

Because the unstable isotope U, TH, K are in ppm. Trace amounts that provide just enough but not to much.

• 1. Iner Core - Solid
• 2. Outer core - liquid
• 3. lower mantel
• 4. upper mantel
• 5. Athenosphere
• 6. lithosphere
• 7. crust - oceanic thin & dense, contintel thick and bouyant.

• BigBang was the birth of all elements.
• Condensation - elemental gases condesnse to for solids
• Accretion - they begin to colide and stick to gether to form increasingly larger rrocks, metors, planets.

• Same number of protons diffrent number of nuetrons.
• thus they are unstable and decay
• they have a half life.

• rare class of metorite
• most primitive objects in universe
• *same element ratios as the sun

• H - hydrogen
• He - Helium
• C - Carbon
• N - Nitrogen
• O - Oxygen
• Fe - Iron 
• Some proton electron configurations are favoured some are not.

Iron  ~500/year

• A silicate liquid forms Si & O
• A metal Liquid forms Fe & Ni

• It is very similar to the layers of earth
• outer layers are silica oxygen rich
• inner layers are iron nickel

terestrial are closer to the sun, composed of rocky silicate mantel (mercury venus earth mars) high density planets, relitivly small

juvian further out lower temperatuire condenses H He, low density

Yes, water erodes while tectonics build. If it werent for plate tectonics water would turn the earth flat.

-Rolling topography -Cloudy, thick atmosphere -High surface temp (200 C)

cold, windy -tremendous topography -volcanism -ice caps -water? (one time) -life? (maybe)

-water, ice -land, sea -rivers, lakes -continents -topography -temp gradient -humans

Plate tectonics require internal energy, the lack of change in planets suggests they lack this internal energy or it has since died out.

• Just right distance from Sun to have water as either a solid, liquid and gas
• Water cycle – (closed system) • Results in a young regenerated surface
• Also enables life to evolve – exchange of gases and elements between earth and atmosphere
• Internal heat – radioactive decay of elements • Creates movements of surface
• Convection (movement) in solid rocky interior (over long periods acts as a liquid)

S-waves do not travel through water because liquids lack shear strenght. We can record that s-waves do not travel through the outer core thus it must be liquid.

• began when wegner proposed the thought that continets apear to fit together like a puzzle - they must have somehow drifted away - why are similar fossils found on different continents?
• Theory rejected - no proof of driving force - wegner not a geologist

1950's WWII - sea floor exploration for submarines identified amazing underwater topography (MOR) Marrie thorp drew maps

magnetic patterns indicated sea floor spreading

now we have a driving mechanism

• 1. continental shelf margins fit like a puzzle
• 2. paleontology - fossils of things that canot swim or fly found across vast oceans
• 3. topography- folded mountain belts that end at one continent and begin on another.
• 4. glacial deposits - movement of glaciers leave distinct marks showing movement at the equator.
• 5. paleoclimatic belts - things formed only in warm climates are found in acient rocks at the poles (coal, limestone from coral)

at MOR tension pulls the rock appart, magnetic patterns are recorded in the new earth, this is the driving mechanism for continental drift.

• spinning electricly conductive (Fe) fluid creates a magnetic field.
• magnetic minerals align in new basalt to record the location of these magnetic poles. evidence of continetal drift and polar wander

• faster ridges - thicker stripes
• less reversal thicker stripes

• record of the magnetic pole recorded in rocks of different ages
• provides a history of continetal movement

magnetic mineral aling in higher inclanation near the poles and lower almost horizontal inclanations near the equator

• Over time the poles appear to wander all over the place specific to each continent
• if we account for continental drift/seafloor spreading they will in fact line up to a comon pole

plates are made of the rigid lithosphere, these "float" on the asthenosphere

NO! convection of the asthenospher is caused from the conductive cooling of the lithosphere.

• rather the driving force is older cooler more dense oceanic crust subducts and creates tension which pulls apart the MOR. As the crust at the MOR becomes thiner it sinks creating the valley in the middle. (on continets this is the rift valley)

• The pacific moves much faster ~15cm/yr vs atlantic ~4cm/year
• this is because 1) it is older/more dense thus more "ready" to subduct. Also it surrounded by more subduction zones, thus there is more room for it to disapear...this is why there is the pacific ring of fire while the atlantic is calm volcanism.

It would make the earth huge and hollow. 

finger nail growth

• ROV
• Submarine
• samples from ocean drilling
• ophiolites

ancient oceanic crust exposed on land.

areas of the sea fllor 3-6km deep, inactive, high sedimentation. typically the area from the edge of the continetal slope to the MOR

• the melting point increases with pressure
• i.e. it takes higher temperature to melt rocks under great pressure.

THIS IS WHY THE INNER CORE IS SOLID!

It has active volcanism however it is a passive mantel upwelling.

• this is the angle between the overiding(continetal plate) and the subducting plate.
• the older/denser a oceanic plate is the faster it subducts/the greater the dip angle.
• 

• at continental rift valleys
• tensions pulls and thins the plate, thus it begins to sink, this continues until a large basin forms...the red sea

• cold water sinks into cracks in the plate near a MOR. this water is heated, becomes element rich, some of it is expelled near the MOR (smokers)...
• Some water stays in the plate (bound in rock) and is cariied all the way to the subduction zone where it is realeased (through melting of the subducting plate)
• the water is hot and more bouyant so it rises into the overiding plate, lowering the pressure, allowing for melting, thus the volcanic belts like cascades, and why the eruptions are so explosive.

every 100 mil year

1. by area - continents colide, india nad the himalaya

2.by mass - new magma from sub zone. Hydrous minerals help to create differeing composition 

stress is the force strain is the result

i.e. stress creates strain

rockies, alps, andes, himalayas

• adjustment due to gravity
• crust bouyant, mantel dense
• iceberg/log in water analogy

brittle lose cohesion breaks/fractures

ductile perment lose of shape but doesnt break...it folds

Presure(depth)  &   strain rate

silly putty analogy

• units in pascal
• Presure= p*g*z
• p=density 2800kg/m3
• g=gravity 9.8 m/s2
• z= depth (m) 30,000m

• 1. normal - tension/pulling = verticle movement, hang wall down
• 2.reverse - compression/pushing hang wall up
• 3. slip lateral slide

3km = 1000bars = 1kbar = 0.1 gpa

area of subduction zone where deep earthquakes happen....proved subduction zones

• 1. divergent - shallow narrow zone ~15km
• 2. transform - shallow
• 3. convergent - wider belt shallow, int, and deep D>100km

• foucus is exact point
• epicenter is verticle translation to the crust

because rocks under greater pressure are stronger. also more ductile

• MOHO - 35km crust/mantel boundry
• Low Velocity 100-250km mantel almost melted
• 410km phase change in mineral structure
• 660km phase change in minerals
• 2920 core mantle boundry