EOS 460 Flashcards
age of universe
14 billion years
G
giga 10^9
Milky Way size
100,000 light years
light year
9x10^15 m
3x10^8 m/s)*(3x10^7 s/yr
size of a H nucleus
10^ -15 m
size of the universe
10^26m
41 orders of magnitude larger than H nucleus
M
mega
10^6
reductionism
understanding by reducing whole to fundamental laws of physics
chaos
- outcome is sensitive to tiny changes in initial condition or constants
- long-term prediction impossible
- weather, butterfly effect
fractal system
- looks the same over a range of scales
- cannot tell size of object without scale bar
problems with reductionism
- gap btw theory and implementation
- cannot see larger scale properties, patterns, relationships
systems thinking
- whole is greater than sum of parts
- relations btw parts = emergent properties = important info
- eg. living organisms
Basic principles of systems
- cannot predict full significance of object w/o observing movement
- full understanding not evident w/o understanding relationship w/ larger system
- evolution over t of larger rltshp related to larger system
equilibrium
- minimum E state where there is no further tendency to change
- properties constant
steady-state disequilibrium
- natural systems
- remain in narrow bounds
- eg. living organisms
to maintain disequilibrium
external E source required
negative feedback
response counteracts input
water vapour feedback
Increased CO2 –> increased T –> Increased atmospheric water vapour –> increased T –>..
for systems to have longevity they must
recycle!
-eg. rock cycle, water cycle
characteristics of natural systems
- in movement (eg. Earths layers all move)
- sustained by external E source + E flow within (sun, radioactivity)
- matter cycles within providing sustainability through recycling
- normally steady-state equil. (eg. narrow range of T’s w/ t)
- feedback sustain steady-state conditions
- systems w/i larger systems
- ∆ w/ t (creation, evolution, death)
Gaia
-steady-state disequilibrium characteristic of E’s surface makes it a ‘living organism’
Atomic reaction, time
10^ -9s
26 orders of magnitude
K
kilo
10^3
Milky way, stars
ca. 400 billion
star spectra
- view stars w/ telescopes containing prisms to examine their spectra
- dark bands break up otherwise continuous colour spectra created in stars atmos. (by absorbing select frequencies of light)
light interacts w/ atoms by
exciting electrons to their next available E level
-requires exact right amount of E
the suns light spectrum, name
Fraunhofer spectrum
spectral lines of distant stars
- shift toward red
- ‘bar code’ remains same
- Doppler effect
Doppler effect
sound/light sources travelling away have to travel farther to reach us, causing our sense organisms to detect a lower frequency
Galaxy movement
-speeding away from us at 180million mi/hr
Parallax
- measuring distance to stars using ever growing baseline due to movement of sun
- can measure out to ca 10^15km
Headlight method
- measuring distance to stars in other galaxies by blinking rate
- stars of same luminosity have same blinking rate
- determine rate –> use nearby star as proxy to determine luminosity
- use luminosity to determine distance
The Local Group
- Milky Way
- Andromeda
- Triangulum
how to date the beginning
- every galaxy moving apart from starting point at diff. velocities and diff. distances away
- use distance travelled and speed of travel to determine origin (w/o knowing where origin was)
- 13.7 by
all objects above 0 K
emit radiation relative to their T
- blackbody radiation
- can be used to estimate T
λ of emitted radiation
- decreases w/ increased T
- at very low T, light is not visible (us, universe)
Universes λ
non-visible glow consistent w/ 2.73K (microwaves)
-after glow of Big Bang
Big Bang support
- velocity/distance rltshp w/ galaxies
- background radiation of universe
- chemical composition of universe
dark energy
- exerts expanding force on universe greater than gravitational attraction
- how universe accelerating expansion is explained
- 70% of the universe
10kyrs after big bang
- enough cooling for e- to be trapped in orbit around nuclei = H, He
- gas cloud beings to break up into clusters
- galaxies evolve
- stars begin to evolve
Nuclear fusion
He – Fe
forming elements > Fe
- star explosion
- supernovae
Terrestrial planet composition
mostly: Fe, Mg, Si,, O
stars consist mainly of
H, He
how do we know star composition
absorption lines in spectra
relative abundance of an element
ratio of element : Si
-# of atoms of x per 1 million atoms Si
abundance vs element #
- general decline, overall sawtooth pattern
- Fe 1000X higher than expected
- Le, Be, Bo many order of magnitude lower than expected
Elements with odd number of protons
lower abundance
=the sawtooth pattern
Nucleus
10^ -15m diameter
- nearly all of atoms mass
- neutrons + protons
electron cloud
10^ -10m
- most of atoms size
- almost no mass
- held together by electrostatic forces
strong force
‘gluon’
- holds protons together despite repulsion
- stronger than electromagnetic force, gravity
- must be touching, only over small distances, 10^ -15
Band of stability
stable nucleus atoms from H to 209Bi
-most favourable N:Z
beta decay
too many N
N –> Z + e-
red giant
large
burn through H more rapidly
Nearing completion of H burning
nuclear fire decreases – unable to resist gravity – collapse – E release – major increased T and P in core – He fusion – Carbon – stable atoms combine to form new ones (2C = Mg)
electron capture
too many Z
Z + e- –> N
alpha decay
nuclei too big
eject He (alpha particle)
Z-2, N-2, A -4
Big star
++ Gravity, ++ Fire, ++Bright, shorter lifetime, produce and distribute (explosion) all elements
- very explosive
- not able to form habitable solar system
escape velocity
- 11km/s
- velocity required to escape from Earth’s gravitational well
- impact on volatile accumulation
Objects outside orbit of outer planets, including Pluto
Kuiper belt
Major increase in impact events
Late Heavy Bombardment
LHB cause
J,S passed through a resonance and perturbed small objects, sending them into inner planetary orbit
small stars
lower gravity
lower T
stable, billions of years, long-lived system
Why is Mercury more heavily cratered
no resurfacing
resurfacing
- tectonics
- volcanism
- water
- biotic
- vertical tectonics
relative dating of a planet
crater density and overlap
why is Mercury so dense
- hug core
- lost large amount of mantle material from impact
Venus atmosphere
- clouds of sulphuric acid
- 90 bars (90X E’s atmos)
- low H2O
- surface 700K
Jupiter atmosphere
- clouds/hazy atmosphere
- banding (fast rotation)
- storms
- H2O
- ammonia clouds
- H/He envelope
Io
- Jupiter moon
- volcanos = lot’s of resurfacing = young surface
Europa
- Jupiter moon
- snowball w/ white/brown ice
- several km ice overlay liquid ocean
- potential hydrothermalism
Saturn
- rocky core, H/He envelope
- lots of rocky/icy moons
- fluid dynamics, Aurora Borealis (E processes not unique)
Titan
- Saturn moon
- organics
- photochemical haze
- methane lakes
- dune fields
photoferrotrophy
4Fe2+ + CO2 + 11H2O —> CH2O + 4Fe(OH)3 + 8H+
photoferrotrophs
- grow at lower light level than cyano
- could have maintained atmosphere O2 10% of today
- keep O2 availability and production low
- create Fe formations?
origin of oxygenic photosynthesis
2.9 Ga
Great oxidation, time
2.4 Ga
oxidized Fe
insoluble
constructed periodic table
Dmitri Mendeleev
Isotope
Different # neutrons
chemically same
completely filled electron shells
noble gases
non-reactive
determines molecules state under specific T, P
volatility
elements with high melting, boiling points
refractory elements
mineral
naturally occurring, inorganic solid with ordered atomic structure, distinct physical properties, chemical composition that can be written as a molecular formula
physical properties of minerals
cleavage, hardness, density, colour, lustre, streak
determine how atoms fit together to form minerals
ionic radium
cations > anions (more e-)
most abundant mineral in upper mantle
olivine
(Mg/Fe)2SiO4
silicates
olivine, pyroxenes, amphiboles, micas, quartz, feldspars
single chain silicates
pyroxenes
non-silicate groups
carbonates, suffices, oxides, halides
double chained silicate
amphibole
oxides
magnetite
micas
silicate sheets
organics essential to biology
carbohydrates, lipids, proteins, nucleic acids
3-D silicate framework
quartz, feldspar
carbohydrate
(CH2O)n
lipid
fats, oils, high energy content/gm
proteins
chains of amino acids
-made from 20 different aa’s
nucleic acids
- long double helix chains
- backbone = sugars, phosphate
- links between chains = bases
nucleic acid bases
adenine, guanine, thymine, urosil, cytosine
solid even to high temperatures
refractories
- solid materials of planets
- not volatiles
stellar fusion =
heat + core contraction
= increased speed
= increased luminosity
change in luminosity since beginning of main sequence
increased 30%
FYS
- Sagan, Mullen 1972
- given lower S, why was early E warm?
Historical T records
- Isotopes (H, O)
- Ice core data (ca. 1mill)
- Forams (150mill)
- Geological indicators
T records from Archaen
- no good isotope data
- ‘normal’ fluvial sediments (not glacial)
solutions to FYS
- lower albedo (surface, clouds)
- stronger greenhouse effect
- stronger heat transport
- stellar physics wrong
- interpretation of records wrong
GHG
gas that absorbs thermal IR
Ammonia
- reduced N
- 10ppm of NH3 would account for ‘the missing 50’
- very soluble, likely to dissolve into ocean and not remain in atmosphere
- photochemically unstable
sun composition
99% H, He
Bode’s Law
distance btw orbits of successive planets increases by roughly a factor of 1.7 (assuming M-J asteroid belt is a failed planet)
Kant-Laplace model
- planets and sun formed from single flat spinning cloud
- evidence: non-random distribution, spin, coplanarity
Planetary mass
determined by gravitational influence
outer planet composition
predominantly ices
inner planet composition
mixture of oxides, metals
planetary density
- depends on element composition and pressure
- consider uncompressed density to make comparable (density at 1 atm)
Earth’s uncompressed density
4.2 gm/cm^3
spherical miners grains unique to meteorites
chondrules
Moon formation
- mars-sized object impacted Earth
- chunk flew off and was retained in E’s orbit
- moon has no core, is similar composition to E’s mantle
rocky planets consist mainly of the ‘big four’
90% O, Mg, Si, Fe
K:U
- extent of volatile depletion
- closer to sun = lower K:U
- large difference btw inner/outer planets
why does Mercury have such a large core and high density
an impact broke off a chunk like E, but it was not retained as a moon
carbonate-silicate weathering feedback
Increased T – increased weathering – increased CO2 drawdown
FYS, CO2
- would need 70,000 ppm for 50 W/m^2
- paleosol data suggests max of 10,000 ppm
- maybe CO2 accounts for 25 W/m^2?
FYS, other gases
- CH4: 100-1000ppm = 8-15 W/m^2
- +other reduced species as minor constituents (C2H2 = 1ppm, C2H6 = 10ppm)
distance from earth to sun
1 AU
If the solar system started over
most likely would not end up the same
FYS, clouds
- more low clouds = less (-) forcing
- less low clouds, more thick high clouds could resolve FYS
- less land = more clouds
was there less landmass in the past
yes, time = accretion
Volume of continental crust vs. time = increasing
Number of molecules in the atmosphere
more atmosphere, more molecules = more scattering = higher albedo = lower T
FYS, N
- higher [N] would increase atmosphere molecules
- increased molecules = increased collisions = increased GHG molecule absorption
- make sure to read more about this
Earth radius
6371 km
Earth density
5.25 g/cm^3
surface rocks = 2.7
core = 11
core-mantle boundary
- Gutenberg discontinuity
- density jump 6-10 g/cm^3
Earthquake waves
- Compressional: material moves forward/back in direction of wave
- Shear: material moves perpendicular to direction of wave
- Surface: pass around surface rather than through interior
Shadow zone
regions where shear waves do not appear (105-140º from origin)
crustal thickness
35km beneath continents
6km beneath ocean
crust-mantle discontinuity
Mohorovic
2.7 - 3.3 g/cm^3
Mantle
solid
2900km
outer core
liquid
2100km
inner core
solid
1000km
Lehman discontinuity btw inner/outer core
core elements
Fe, Ni, some lighter ones
crust elements
mostly granite: quartz, feldspar
some pyroxenes, amphiboles: Fe-Mg minerals
Atmophiles
volatiles, liquid/gas under E conditions
eg. noble gases, H2O, CO2, N2
low density
concentrated in ocean, atmosphere
lithophile
- prefer silicates
- concentrate in mantle, crust
eg. Si, Mg, O2, Ca, Al, Ti
Siderophile
prefer metallic state
eg. Ni, Au, Ag, Cu, Fe, Pt
Chalcophile
sulphur loving
-Pb, Cu, Zn, Pt, As
uniquely falls into 3 of the element groups
Fe - chalcophile, siderophile, lithophile
magmaphile
subset of lithophiles that concentrate into silicate liquid
core/mantle separation hypotheses
- heterogeneous accretion model
- homogeneous accretion model
heterogeneous accretion model
- different minerals added w/ time
- metal first to form core, then silicates, then volatiles
homogeneous accretion
- materials accreted homogeneously then separated into layers over first few 10My
- metals sunk into core (more dense and immiscible w/ silicates)
pressure release melting
rocks that are solid at depth may melt if exposed to surface from reduced P (minerals crossing the solidus)
mantle melting forms
basalts
basalt melting forms
granites
granites melting form
granites
largest CO2 reservoir in crust
limestone
volatile-containing mineral weathering
degassing
redbed
sandstone w/ red oxidized Fe cement = oxidized E
BIF
- reduced Fe, soluble
- indicative of deep ocean anoxia
mass-independent fractionation of S isotopes
MIF
-increased ∆33S implies lack of UV-shieldind
= lack of O3
= [O2] less than 10^-5
where did the O2 come from
- burial of OM = free O2
- H escape increases O2
- oxygenic photosyn from 2.9 Ga
H escape
- must get very high in atmos to escape
- H2O decreases w/ altitude
- H2O is relatively ‘safe’ from photolysis in troposphere due to O3 – but if there is no O3…
how to find other orbiting planetary systems
- look for light of star to dim as planet passes in front of it
- will only work if planets orbit in our plane
- more likely to see planets that orbit more quickly (more dimming of the light)
TRAPPIST -1
- terrestrial exoplanets
- 2500K star (vs sun = 5900K)
- 1-20day orbit
- 39 light years away
exoplanet
planet that orbits a star other than the sun
the habitable zone
- goldilocks zone of insolation
- presence of liquid water not strongly excluded by theory
- water-based life could exist
Earth unique feature
surface conditions are around the triple point for water
inner edge of habitable zone
threshold for runaway greenhouse
runaway greenhouse
260bar of ocean into atmosphere
bake off all limestone
major CO2 inputs
planets moons
- 6/8 planets have moons (Merc, Ven = 0)
- Jupiter: 63, Io, Europa, Callisto, 2 bigger than Merc.
- Uranus: 27
- Neptune: 13, Triton
- Mars: 2 very small
Io
smooth surface, high volcanism
Europa
covered in moving, deforming ice
outer planet moons
mostly low density, consistent w/ cold env’t formation
prograde orbit
circle planet in same direction planet is rotating
Triton
18% > Pluto
farthest part of the solar system
oort cloud
billions of objets
Earth’s moon
- only larger inner planet moon
- unique density, lower than planet (3.1)
- 1% off circular orbit
- 40 - 100Ma younger than chondrites
Possible effects of giant impact events in early solar system history
- Earth’s moon
- Mercury’s oversized core
- large differences btw Mars hemispheres
- reverse rotation of Venus
- horizontal spin axis of Uranus
LHB
- late heavy bombardment
- dozens of impact craters >300km
- 3.9-3.8 Ga
- planetary orbit realignment – unstabalize asteroid belt – particularly when J:S = 1:2
moon moving away from E
38 mm/yr
implication of moon moving away
several hundred million years ago:
- more days and months /year
- shorter days, E spinning faster
- greater tides, higher energy shorelines
oldest E sediment
3.8 Ga
Isua formation, greenland
Cherts, carbonates, BIFs (all require H2O_l to form)
Escape velocity
E: 11.2 km/s
J: 60 km/s
moon: 2.4 km/s – insufficient to hold atmos.
Earth atmosphere composition
N2 78%
O2 21%
Ar 1%
CO2 0.04%
water trap
top of Earth’s troposphere ca. 60ºC, virtually no H2O_v can exist
If Earth were a blackbody, T would be
5ºC
Earth albedo
0.3
If only albedo influenced T
Earths T would be -20ºC
earth mean surface T
15ºC
FYS, present atmosphere
Earth’s T would have been below freezing
molecule with high GHG effect
H2O_v
weathering
3H2O + 2CO2 + CaSiO3 –> Ca2+ + 2HCO3- + H4SiO4
Mineral precipitation
Ca2+ +2HCO3- –> CaCO3 + H2O + CO2
weathering depends on
T, acidity, amount of rainfall
evidence Venus lost H2O_l to H escape
100-fold enrichment of D to H
The Great Oxidation
-2.4Ga
-Corg buried fraction has not changed
-
what you need to make a MIF
- no ozone (need the UV to make it)
- reducing atmosphere
moon hemispheres
lunar maria
lunar highlands
all moon geochemistry comes from
390kg of rock from one hemisphere
what is a climate model
- breaks down problem into simplified parts to try to understand how it operated in the past or future
- mathmatical representation of our physical understanding of the climate system fitted to physical laws
snowball Earth
- frozen ocean - no calcite precip/burial
- CO2 accumulation in atmos.
- sediment evidence: glacial deposits intermixed w/ marine sediment (glaciers reach sea level)
- 10Ma for CO2 to build up enough to melt
magnetic field
- Earth’s larges of terrestrial planets
- from convection of liquid outer core
- some UV protection
habitability depends on
- adequate volatiles
- liquid water
- constant T
- sufficient mass- to retain atmosphere
4 kinds of planetary change
- Random: meteorite, volcanic outbursts
- Biological: species so successful it has planetary impacts
- Inadvertent: so good at solving local problems they unknowingly cause global impact (vehicles)
- Intentional: energy use choices
The Anthropocene Dilemma
your sphere of influence exceeds your sphere of awareness
Anthropocene a new epoch or eon?
-much bigger deal if Eon - only 4 in all of E’s history - the fundamental planetary changes
Evidence of redox state
- redbeds, BIFs
- detrital minerals
- minerals in palaeosols
- S isotopes
- trace metal abundances
water present
- at least as early as 4Ga
- Zr show possibility of liquid water at 4.4Ga
S has decreased
30% !
Earth Ts
appear to have remained w/i 0-100ºC through geo time
older of age of surface, oldest to youngest
Mercury, Mars, Earth, Venus
Pangea break-up
225Ma
thickness of lithospehre
increases linearly w/ square root of age
K/T extinction
- volcanism caused instability
- meteor exacerbated the problem
P/T extinction
-no impact evidence
mean ocean depth
5000m
continental drift theory
- Alfred Wegener, 1912
- fit continents together by looking at continental margins
- formations, fossils across ocean basins matched
- glacial deposits in Africa, SA
- plate tectonics unknown at this time
spreading rates
-1-20cm /yr
Benioff zones
-fault between descending ocean crust and overlying mantle in a subduction zone
plate tectonics
- Mt belts built at convergent margins
- volcanic mt ranges caused by subduction
- oceans are continually forming and recycled
- earthquakes and volcanoes are the result of plate movement and mantle convection
- oceans deepen away from MOR b/c plate is progressively thickened as it is cooled
age of ocean floor
max ca. 150 million years (4% of E’s history)
flow in response to density differences
convection
high Rayleigh numbers mean
- convection occurs
- temperature differences, thermal expansion, density differences
- R >2000 convection inevitable
- R_mantle = 1million +
Earth’s volcanism is focused
- at plate boundaries (90%)
- intraplate/hot spot volcanoes important also (Hawaii, Yellowstone)
Ocean ridge key points
- ridge geochem processes sustain chemical composition of ocean
- storage/transport of H2O/elements to subd zone permits volcanism, continental growth
- role in carbon cycle and climate stability
- possible role in origins of life
subduction earthquakes
110km above benioff zone
oldest rocks
Acosta Gneiss, Canada
4.03 Ga
Early atmosphere [O2]
less than 10^-10 PAL
Earth energy revolutions
- autotrophy
- oxygenic photosynthesis
- oxygenic respiration
lag in atmosphere oxygenation
- reduced S/Fe reservoirs were a large O2 sink
- reservoirs had to become saturated before atmosphere could accumulate O2
which period did reptiles first appear
carboniferous
stratigraphic scale of mass extinctions
cm’s
land plants first in record
silurian
ATP from aerobic respiration
36
ATP from fermentation
2
placer deposit
fluvial gravel deposit
four fundamental forces increasing in relative strength
gravity, weak, electromagnetic, strong
what determines how elements fit together in minerals
ionic radius
where have the most meteorites been found
antarctica
largest astroid
Ceres
how is lunar regression measured
bouncing light of a mirror on the moon
proportion of volcanic output from MORs
80%
on what timescale is an ocean of water cycled through the terrestrial freshwater system
30,000 yrs
residence time of Na in ocean
47Myr
