Plate techtonics

Plate techtonics -> equivelent of Survival of Fittest in Biology

3 major Boundry Types

1. Ridge
2. Divergent margin
   1. Formation of new oceanic crust by sea floor spreading
   2. Ocean crust -> denser, more mafic, basalt
   3. Extensional Regime, normal faults, shallow seismicity
   4. High Heat flow, decompression melting
   5. Intrusive igneous -> gabbro and basalt (essp. pillow basalts)
   6. Highly fractured rocks -> alot of water goes through -> causes differences in carbon weathering
   7. Tends to fault in three geometric paterns (third often failing to spread)
   8. Tends to also have reafs at shelf slope break
   9. Starts by bowing up, then breaking, finally filling with lakes then ocean
   10. Oceanic crust is much thinner than continental crust
3. Convergent Margin
   1. Recycling of old, cool oceanic crust (subduction)
   2. Older = Colder = less boyant
   3. Reverse or thrust faulting
   4. Deep seismicity
   5. Increaed Temp = Partial melting of mafic crust = felsic magma
   6. Compression leads to deformation, metamorphism and mountain building
   7. Water, accumulated in pourse ocean basin
   8. Water brought down into asthenosphere = decreasing melting point = more rising magma = mountain building
   9. Also, happens in Continent Continent collision (India subducting under Eurasia) -> causes deformation = himalias
   10. Also, happens in Ocean Ocean collision -> causes island arc = japan
   11. When passive margin collides, subduction reverses causing forlorn basin (like western interior basin in N. America)
4. Transform margins
   1. No new crust forms
   2. Shear regime -> strike-slip faults, shallow seimicity
   3. San. Andres
5. Hot spots are fixed points, thus things like Hawaiian islands, show direction and rate of plate movement
6. Magnetic liniations -> lavas on land dated, and reversal history -> reversal history matched to magnetic liniations, giving us time frames

Driving Forces

1. Mantal Convection (differences in heat)
2. Ridge push or slab pull? -> slab pull is thermal model, push is topographic model
3. Subducted material goes down to the core mantel boundry
4. Icehouses and Greenhouses, match up with rates of volcanism
5. The Wilson Cycle (200my cycle), length of ocean basins determains CO2 levels

Implications

Rivers

Hypsometric profile (a significant portion is between 2 and 0 or -4 and -6)

Trenches (found where plate is subducting)

Abyssal planes (Oceanic crust spreading away from trench tword subduction)

Elevation = f(uplift – erosion) or techtonic activity – climate

Both uplift and erosion do about .01 – 10 mm/y

A difference of .5mm/y -> 5 km over 10My

Agents of Sediment removal

1. Glaciers -> not alot of work
2. Streams -> doing alot of work

Hydrologic cycle (Evaporation and Precipitation)

1. Oceans E>P
2. Land P>E

Streams are small (1 bases point) and short lived (2 weeks), but they do all the work

Underground water -> huge amount, flows tword sea, we don’t know alot about it (could be HUGEly important, but noone knows)

Rivers

1. Amazon is in rainforest (hot and wet) so its not a surprise it has a high flux to drain ratio (heat and pressure are the controls on chemical weathering
2. Water Table -> cut off between surface and ground water
3. Laminar flow vs Turbulent flow (laminar is mellow, turbulent causes erosion)
4. Sheet flow vs Channel Flow (sheet is water across land which forms into channels)
5. Controls
   1. Velocity of flow (function of gradiant)
   2. Geometry (depth, shape)
   3. Density and viscosity (almost always water)
   4. Surface roughness (what its moving over)
   5. Infiltration capacity
   6. Pre-existing features (special things)
6. Friction is a good control of velocity
   1. Streams deposit in point bars (where water is slowest)
   2. Flooding causes fine grain to deposit in plane around the river
7. Channel types
   1. Broad and shallow (arid environment, fast, desert flash flood)
   2. Deep and narrow (meandering streams, human enviornment, mostly suspended load, more coheasive soil)
8. Channel Pattern
   1. Proximal, Aird climent, bed load streams
   2. Distal Humid Suspended load
9. Grain size is a function of flow velocity above mud
10. Below sand -> clays stick together acting like larger particals
11. Bedload -> stick to bottom, move through rolling, sliding, saltation
    1. Creates bedform
    2. size of particals = competence, controlled by speed
    3. Number of particals = discharge
    4. grains build up in beforms (like sand dunes)
    5. Ripples are 1-3 cm
    6. >3cm = dunes (some times fractals)
    7. Ripples form at low velocity
    8. Dunes at high
    9. Flow Regine concept
12. Suspended load -> carried through turbulation
13. Types of Streams
    1. Aluvial Fans
       1. Poximal
       2. Arid -> High velocity
       3. Intermittant
       4. Immature
       5. Bedload
    2. Braided
       1. Broad Shallow channels (really shallow)->Dominately bedload
       2. Transporting sand
       3. arid to semi-arid->Sparse vegitation
       4. Easily eroded banks
       5. Veriable flow
       6. Course to Medium Grained
       7. Poor to Moderate Sorting
    3. Meandering Stream
       1. Has the cutbank and point bar (one is on the other side of the other)
       2. Fining upword sequance
       3. Oxbow lakes (abandoned loops due to flooding eroading a new path)
       4. Distal, humid,veg, lowlands (veg soils are more cohesive making them harder to erode)
       5. Single deep channel
       6. Constant flow and high velocity
       7. Suspended load
       8. Finer Grained, moderate to well sorted (due to loss of grains because these are distal, sorting is proximal vs distal)
       9. Lateral Acreation surfaces (where you can see the fining process)
       10. Higher sand to mud ratio
    4. Deltas
       1. Stream velocity drops -> as does sediment (both bed and suspended)
       2. Progradation
       3. Characterized by modifier
          1. Delta Dominated by River (Mississippi, litterally pushed out into ocean)
          2. High wave action (barrier islands)
          3. High tidal ranges (pushed back in leaving elongated bars)

Drainage Networks

1. Basins vs Devides
2. Drainage Patterns
3. Landforms -> stream Terraces, incised meanders, etc.
4. Base Level Concept (surface to which erosion is working), below accululation, above erosion

Geologic Time

Hutton -> Lyell + Steno

Uniformitarianism

Laws -> methodological
Process  -> methological

Rate -> substantive

State -> Substantive

Methodological is right, substantive is wrong

Geopetals -> fossils, riple marks, etc

Original Continuity -> strata which are now seperate were originally together

Fossile content allows us todo corrilation

If things crosscut, then they are younger than what they crosscut (duh)

Flow has a vasicular texture on top

a sill has a bake zone on both top and bottom

Index Fossils -> good skelletons

Disconformity -> both erotion and sedement can produce one

Sequance statigraphy (how to subdevide rock record)

Diachroneity ->  same thing two different times
When a basen subsides it sinks

Lithostratigraphy (formal naming of rocks based on their lithological units)

Uranium -> Lead dating

Argon -> Argon dating

Argon doesn’t agree with Uranium

Some fossils are Diachronous

Chemostratigraphy -> use of chemical marker for dating

Sed Rocks -Con’t

It takes 2 moles to weather ignious rocks, but only 1 mole is returned by the calcium carbonate. So silcate weathering consumes CO2

Lithification process

1. Compaction
2. Dissolution
3. Precipatation
4. Recrystalization
5. Cementation

Facies Concept

1. Unique to where a rock forms
2. Sediment transported to shore line
3. sand facies is very high energy
4. finer grain caries through sand to mud
5. very little carries out to the carbonate faces
6. Sand stone to mud stone to lime stone
7. Facies can only be ontop or below ajacent facies
8. The order in which they’re array’d gives us the sea level history (transgression or Regression)
9. Durring regression erotion takes place

Major depositional environments

1. Weathering and erosion (proximal) -> source rock and climate
2. Transportation and sedimentation (updip to fluvial) -> distance, gradient, energy level (lakes vs river)
3. Shoarline (dunes)
4. Deltas
5. Deep Marine
6. rate of sink matters

Eluvial system

1. Fan (not clay because not enough time) basement stuff (felpars)
2. Braided (broad and wide streams)

Eolian depositis ->

1. fine grained (weathered by wind)
2. between proximal and distal
3. Dunes migrate ontop of eachother

Meandering streams

1. Big and deep
2. flood eluvial vally
3. deposits silt and clay
4. going down: High energy to low energy

Delta

1. Sudden energy drop
2. While global sealevel is rising, the mississippi is regressing because of sedemens
3. Opposite gradiant: find to course grain due to regression

Reaf system

1. Limestones and dolastones (from magnesium from lagoons)
2. Both high and low energy (high from ocean, low from lagoon)

Turbidites

1. Clay -> courser then back to cley suddenly
2. Graded bedding
3. Energy of the flow highest when it gets to the site
4. head of flow is course tail is finer.

Important stuff that didn’t fit anywhere else

1. Lacustrine Deposits: Varves
2. Layering caused by lakes
3. Diagenisis -> everything not metamorphic
4. Basement = Igneous rocks
5. felspar becomes clay, but it takes time

Metamorphic rocks -> represent changes that occer in solid state (prior to melting)

1. Recrystalization
2. Phase changes
3. Neo Crystalization
4. Pressure solution ->the contact (touching point) is desolved between grains
5. Deformation -> contact is not desolved
6. Tend to find them in Precambrian sheilds and occationally folded mountain belts (due to their tectonic activity)
7. Temp, pressure, fluids

Lithosphere goes down into mantal to stenosphere

Igneous Rocks

Processes

1. Start off in the mantel and move out
2. Two kinds: intrusive and extrusive
   1. Intrusive are under the crust and take long to cool (big crystals)
   2. Extrusive are volcanic and cool quickly (course)
3. All part of the rock cycle
4. Magma and lava – Controls
   1. we can do phase diagrams, except we flip the y-axis to represent depth
5. Sources of heat
   1. Radiogenic decay (biggest)
   2. Impacts (meteorites)
   3. Gravitational Compression
   4. Sinking of Fe Alloys
   5. Tidal Frication
6. To tell heat under the surface we find pressure gradiant and temp at surface and use adiabate to determain heat at depth
7. We can cacluate preasure from gravitation
8. Two melting curves for dry and wet (weather they contain volitiles) effecting how it melts
9. Due to shape of curves decompression of rising magma causes it to melt
10. For main causes of differentiation (the different make ups of igneous rocks from minerals)
    1. Differences in magma sources
    2. Partial melting (gaining bouyancy)
    3. Country rock (picking up shit on the way up), breaks off in xenoliths and melts, or melts on the sides
    4. Fractional crystalization
11. Differentiation tends to be a comparison between high in Fe, Mg (mafic and ultramafic from the mantal from #1-2) to high Si, Al (felsyc from #3-4)
12. Geotherm veries, average of 30*K per km (60*K in a basalt)
13. Minerals – Bowen’s reaction series (melting points of minerals) -> olivine is high quartz is low, Plaglioclase is both
14. Texture -> Rapid cooling is Fine-grained (aphanitic), slow cooling is Coarse grained (phaneritic)
15. Porphyritic is a combination of aphanitic and phaneritic
16. Distribution of igneous rocks
17. Plate techtonic decide spreading of igneous rocks (mafic) through decompression cooling at divergant margins
18. Subduction pulls under contental plates (fasyc) also known as a convergant margin
19. Basaltic volcanism can happen in the contenants due to sufrace composition
20. Caldera = colapsed volcano
21. Snake river plane in Yellow stone demonstraits the movement of plate techtonics (the place of the volcano keeps moving)

Minerals

Carbon Cycle con’t.

1. Carbon Cycle interacts with not just atmosphere but ocean and earth levels.
   1. Caronate rock weathering -> CO2 is absorbed by the rock into ions in the ocean -> this CO2 is later returned
   2. Silcate rock weathering -> CO2 is absorbed by silcate rocks -> Only half of this CO2 is later returned
      1. Silicate rock weathering reduces
2. Rock Cycle
   1. Magma comes up
      1. forms in the core: Intrusive
      1. forms at the surface: extrusive
   2. Weathered at the surface -> transported, deposited
      1. forms sediments
   3. Sediments are heated into metamorphic rock
3. 3 kinds of rocks
   1. Igneous -> unorganized crystals
      1. crystal growth stopped by the growth of other crystals
   2. Sedimentary -> sandish
      1. Rounded (worn down) -> different sizes because of different levels?
   3. Metamorphic -> organized non-crystals
      1. flattened and uniform direction (perpendicular to the source of force)
4. Goldilocks Principle -> First three rules of heat/realistate -> CO2, CO2, CO2
   1. CO2 concentration is modulated
   2. Carbon cycles because earth has an active plate tectonic system

Minerals

1. Interfacial angles are important
2. Can have defined, specific, invariable chemical formula
3. Can Have a range of possible chemical formula (Illite)
4. Five different ways they form:
   1. One I missed
   2. Percipitate
   3. Solidsate fussion
   4. Bio mineralization -> animals secrete Calcite and Aragonite
   5. Fumeralic mineralization -> vulcanization
5. Uhedral vs AnHedral (unlimited vs limited in growth)
6. Bragg’s law = X-Ray Diffraction to determain crystal type
7. crystals can have defects -> Steve Jacobson
8. Compesition of the Core
   1. Meteorites
   1. Density Simulation
   1. High pressure density experiments
9. Most abundant elements
   1. Whole earth: Fe, O Si, Mg (Ni, S, Al, Na, Ca, K)
   2. Surface: O, Si, Al, Fe, (Mg, Ca, K, Na)
10. Major mineral groups
    1. Silicates (SiO4)-4
    2. Carbonates CaCO3
    3. Oxides Fe2O3
    4. Sulfides FeS2
    5. Halides NaCl
    6. Sulfates CaSO4
    7. Native elements Au, Ag, Cu
    8. Anionic classification (classified by anions)
11. Silicates
    1. Shape
       1. Isolated tetraherdra (high melting points)
       2. Chains
       3. Sheets
       4. 3-D (low melting points)
    2. Ferromagnaesian (darker denser) vs NonFerromagnesian (lighter and less dense)
12. When you weather granite you produce:
    1. Quartz (in equilibrium) breaks up but stays intact as Quartz in beaches
    2. Feldspar (out of equilibrium) and degrades into clays
13. Briditites comes up to form Basalt
14. Granite comes up to form Sandstones and Clays

Overview

Scales of Measurement

Earth Systems

1. Two engines
   1. Sun
   2. Core
2. Plate techtonics
   1. heat wells up and is carried under contenants (subduction)
3. Sun’s luminocity: gets hotter over time
   1. Old earth cold (look at mars)?  No ->  green house gasses (look at venus)
   2. CO2 removed from old atmosphere
   3. Goldilocks effect
4. Earth’s interior
   1. Density control -> denser matter nearer to center (iron and metal oxide)
5. Orbital characteristics
   1. Seasonality -> tilt in axis in rotation
6. Atmosphere -> radiative effect (trapping infrared)
7. Climate -> average temp = 15 *C (1*F at the equator = 12*F at the poles)
8. Circulation
   1. two deep places of water near the poles
   2. Sea Ice formation -> denser (colder) water
9. Internal Earth
   1. Heat
   2. Mantal convection
   3. Plate techtonics
10. Rock Cycle

Earth System

1. Open System ( energy and mass transfer)
2. Reserviors
3. Fluxes
4. Residence times
5. Origin -> observation of other systems in formation
6. Inner (terrestrial) planets
7. Outer (jovian) planets colder, gassier
8. Collision of newly formed earth
9. Radioactive decay heats interior
   1. 40K => 40Ca => 40AR
10. Pangea
    1. Mountains across contenants
    2. fossils on different contenants
11. Submarine warfair of ww2 = better understanding of plate techtonics
12. Movement of plates determain placement of contenants
13. Passive margin (easter US) vs Active margin (which causes subduction)
14. Contenants pushed apart by plate techtonics and brought together by subduction
15. Water moves perpendicular to the wind (creating the gulfstream effect)
16. 1sv = 10^6 m^3/s
17. Gulfstream heats europe
18. 100ppm = 42% change of glaciars