(plate tectonics) - university of british columbia · global plate tectonics. • lower boundary:...
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Active geological processes
(Plate Tectonics)
Water in all three states
Life!
Press & Siever, 2001. Ch 21.
Plate Tectonics!
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Press and Siever, 2001
Hydrothermal Convection/Alteration Systems
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Earth’s Atmosphere: A membrane between the biosphere and the cold vacuum of space
CIRCULAR CAUSALITY: Life manufactures the membrane that makes Earth’s surface habitable.
Why
is th
ere
stat
ic !
nuclei ≈ elements
Nucleosynthesis - A Self-Organizing Proces
1. Our Sun : 4 1H 4He + “2e- ”1 50x1060K 2
E = mc2
describes stupendouenergy yield
Nuclear Fusion :
Yields new elementsand energy to sustain the fusion reaction
Self-Organization:The emergence of order in the absence of a pre-existing
template
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2. Larger Stars with higher To fuse larger nuclei
eg. 4He + 4He 8Be + “energy”2 2 ∆ 4
8Be + 8Be 16O + “energy”4 4 8
Nuclear fusion “works” up to synthesis of 26Fe
SUN
“Red Giant
= H fusion
3. RED GIANT runs out of fuel Gravitational collapse Explosion (Supernova);27Co - 92U via Neutron Capture (“sticky bullet
Nuclear fusion Neutron capture
Elemental Abundance in Our Solar System
Divisible by
four
“odd-even pattern”
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A. Cosmic Nucleosynthesis: Singularity H and He in an Inflationary Unive
B. Nuclear Fusion (2He - 26Fe): 4H He + ENERGY in our Sun; larger nuclei are fused in larger stars fuel-exhausted massive stars collapse and explode!C. Neutron capture (26Fe 92UCo ): Exploding supernova shatters some nuclei; free neutrons like “sticky bullets”; neutron proton + e- ; e.g. 27Co 27Co; 93Np 103Lw = synthetic
Our Solar SystemSun = a very ordinary, small star; one of 200-400 BILLIONStars in our Milky Way Galaxy. The Sun is at the center of our Solar System ( Sun, planets, asteroids, comets and “dust”)
All of the planets:1) Lie in a plane (ecliptic)2) Possess concentric, nearly circular orbits around Sun3) Revolve in the same direction4) Record an outward decrease in density:
Inner / Terrestrial / “Rocky” Planets (Earth)
Outer / Jovian / Giant “Icy” Planets (Jupiter)Detective work: Can we use this
evidence to reconstruct “the crime”?
M + “AB” J S U N(P)SUNOxides Ices
MgO, CaO, FeO, SiO2
H2O, CO2, NH3, CH4
Inner / TerrestrialAsteroids
Outer / JovianComets
Whirlpool…
A self-organizing dynamic system //
A dynamic process structure (a nerb) All DPS require a gradient; the DS acceleratesdegradation of the gradient to access free energythat is utilized to perpetuate the dynamic process structure .
that’s kind of mind-bending… (?)
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M + “AB” J S U N(P)SUN
*Interpretation: Sun ignites via nuclear fusion Solar windpropelled differentiation by volatility
Oxides IcesMgO, CaO, FeO, SiO2
H2O, CO2, NH3, CH4
Inner / TerrestrialAsteroids
Outer / JovianComets
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Iron catastrophe
“Big Burp”(retention ofoutgassed Water and other volatiles
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Global Recycling System (Plate Tectonics)
Water in all three states
Life!
Dynam
ic Planet…
Press & Siever, 2001. Ch 21.
Plate Tectonics!
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Active plate boundaries: Earthquakes & Magmatism.
ftp://ftp.ngdc.noaa.gov/MGG/images/slide set1/slide18.g
“RING of FIRE “
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BA
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Atla
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Magnetic Stripes: Reveal SymmetrySeafloor Spreading Age of Crust
Dynam
ic Planet…
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Press & Siever, 2001. Ch 21.
Plate Tectonics!
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“ROCK”(“Granite”) “Sand” + “Mud” +”solutes”
H2CO3
LIFE
GLOBAL PLATE TECTONIC SYSTE
CHEMICAL WEATHERING
Convent ional plate te ctonic hyp oth esis:1. Radioactive decay propels heat and ma tte r t ransfer via
convect ion of Earth’s ma ntle , through wh ole-mant leconvect ion or a st rat igrap hy of sma ller convecti vesyste ms.
2. The combined processes o f slab pull, tractional dragand/o r trench pull (et al.) ar e credite d for th emoveme nt of Eart h’s tect on ic plat es upon a lowvelocity — and presuma bly low v iscosit y —asthenosphere .
3. Subduction processes an d dehydration o f minerals inthe down going slab permits part ial me lting of oc ean iccrus t and lith osphere, resu lting in arc magmat ism andgenerati on o f new cont inental cr ust .
4. Water plays a key m odifying role in ma ny or al l ofthese phenome na
Tectosphere : the realm of global plate tectonics.• lower boundary: the base of the asthenosphere,
the low densit y/low-velocity, semi-plast ic andpa rt ially molte n la yer in th e u pper ma ntle u ponwhich plat e tect onics glide s
• upper limit: defined a t the upper limit of the crust;
• The tectosphere is characterized by inte ractionwith and mutual alteration of/by surface-derivedfluids, particularly water.
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Prominent phenomena of the tectosphere
• Formation (partial melting and quenching)of rigid tectonic plate (oceanic crust and lithosphere =oceanic tectosphere) at divergent plate boundaries;
• Plate motion• Consumption of hydrated oceanic tectosphere in subduction zones where partial melting, magmatism, plutonism, earthquakes and mountain building are concentrated, and volatiles are recycled.
• Low-velocity/low-viscosity zone (“slippery layer” = asthenosphere)
Press and Siever, 2001
Hydrothermal Convection/Alteration Systems
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HO
T, reduced, acidic “out”ß
COLD, oxidizing, alkaline “in” Age (Myr)
Seab
otto
m d
epth
(km
)
Generalized Subsidence Curve for Oceanic (Tectosphere) (Sclater et al., 1992)
2.5
0 904.5
(d=d0 + a (t 1/2)
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2.5 km
4.5 km
Slab pull Convective advective heat
transfer
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DEP
TH (K
M)
CalculatedGeotherm beneath
Island Arc Philpotts,
Temperature (°C)
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Water permits partial melting in subduction zones;H20 is derived from dehydration of hydrated minerals in slab
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Earth’s Atmosphere: A membrane between the biosphere and the cold vacuum of space
CIRCULAR CAUSALITY: Life manufactures the membrane that makes Earth’s surface habitable.
“Granite”Weathering
Sediments; solutes ⇒Life
H2O , CO2; sunlight
exosphere“Wet Tectonics
and Autocatalytic Planet
“plate tectonics & “rock recycling”
QuickTime™ and aPhoto - JPEG decompressor
are needed to see this picture.
From glycolysis & POOxaloacetate: product AND
catalyst
CITRIC ACID (“Krebs”) Cycle:
An example of AUTOCATALYSIS that is fundamental to cellular metabolism
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Life/environment
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July 19-20, 2002Universities Space Research Association
College and University Earth System Science Education for the 21st CenturyQuickTime™ and a Graphics decompressor are needed to see this picture.
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Atmospheric Physics/Dynamics
Tropospheric Chemistry
Global Moisture
Ocean Dynamics
MarineBiogeochemistry
Terrestrial Ecosystems
Terrestrial Energy/Moisture
Climate Change
Pollutants
CO2
CO2
Soil
Land Use
Physical Climate System
Biogeochemical Cycles
Human Activities
(from Earth System Science: An Overview, NASA, 1988)
The Bretherton Diagram
“BOX MODEL APPROACH”
EN
ER
GY
WAVELENGTH
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“ROCK”(“Granite”) “Sand” + “Mud” +”solutes”
H2CO3
LIFE
GLOBAL PLATE TECTONIC SYSTE
CHEMICAL WEATHERING
Solubility “Pump”
Cold water rises and warms:
OUTGASSING of dissolved CO2 to
atmosphere
Warm water cools and sinks: “INGASSING”of atmospheric CO2
into ocean
Coastal “Green”Ocean
Deep “Blue” Sea
Oceanic “bio-provinces”
Biological (CH2O)“Pump”
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Limestone (CaCO3) “Pump”
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Marine sediments
Recorders and Participants in Earth’s
Environmental Evolution
Geophysiology: “Wheels within wheels..”
Huge and slow (106-107 yrs):Chemical Weathering &Sedimentation ProcessesPlate Tectonic Processes
Small & FAST (101-<100 yrs)Terrestrial Biota
Intermed. & intermed. (105-102 yrs)Ocean circulation changes*
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Slide 6
Slide 6