Download - Pre- Type II SN Nucleosynthesis (s-process)
Slide 1
Pre- Type II SN Nucleosynthesis (s-process)
21 solar mass star
rati
o t
o s
ola
r ab
und
ance
Rauscher et al. (2002)
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Type II SN Nucleosynthesis (r-process)
Rauscher et al. (2002)
25 solar mass star
Slide 3
Galactic Composition evolution
Chiappini (2004)
Slide 4
Nearby Supernova
Knie et al. (2004)
Slide 5
Interstellar shocks
Clayton (1979)
Slide 6
Silicate Condensation
Clayton (1979)
Slide 7
Significant Events
The oldest crust in today’s oceans is around 0.2 Ga
200 m
Slide 8
Wyoming Craton
Beartooth Mountains
Slide 9
Rhenium-Osmium System187Re 187Os
Half life of about 42 Billion years
The convecting asthenospheric mantle has roughly chondritic
ratios, with
187Re188Os
= 0.4
187Os188Os
= 0.127 to 0.129
Slide 10
Rhenium-Osmium System
PUM
after Shirey and Walker (1998)
Slide 11
0.095
0.1
0.105
0.11
0.115
0.12
1500 2000 2500 3000 3500 4000 4500
Age (Ma)
init
ial 1
87
Os
/18
8O
s
Chondritic Reference
SW Greenland Perid
SW Greenland Chrom
W. Aust Komatiite
Dongwanzi, China
Laurite, Outokumpu,Finland
Archean+ Mantle Osmium
MontanaChromites
18
7O
s/1
88O
s
Slide 12
Timeline for the eastern Beartooth Mts.
3.56 Ga - Lu-Hf zircon age of average Hellroaring Plateau zircons3.2-3.4 Ga - major crust-forming event that yields the dominant
zircon population in quartzites3.1-2.8 Ga - granulite facies metamorphism (M1) (5-7 kbar 750-800ºC)2.78-2.79 Ga - andesitic magmatism and intrusion of
Long Lake granodiorites2.79-2.74 Ga - deformation and amphibolite facies metamorphism (M2)2.74 Ga - massive intrusion of the Long Lake Granite and
local (M3) granulite facies overprint.Some new growth of zircon rims in Hellroaring quartzites
2.74 Ga – intrusion of mafic igneous layered Stillwater Complexin adjacent Stillwater block
1.3 Ga – Rb-Sr and K-Ar emplacement age of alkali-olivine mafic dikes774 Ma – 40Ar/39Ar emplacement age of diabase dikes
(Gunbarrel magmatic event)65-57 Ma - rapid uplift (apatite fission track data) –Laramide Orogeny
(Henry & Mogk, 2003)
Slide 13
from Beartooth Highway, Montana
Hellroaring PlateauChromite Mine
Slide 14
A giant magma ocean and separation of the Earths core:
constraints on these events from tiny, brief experiments
Incandescent Bulb, 2500°CLiquidus of Mantle at 700
km
Kilauea, Hawaii, 1200°C
Slide 15
The Earth is differentiated
How and When did this occur?
Two Sets of Constraints:
Physical MechanismsandChemical Signatures
Slide 16
Timing of Core formation
Slide 17
Heat Sources:
Solar/Magnetic Induction heating (but T-Tauri: Polar Flows)
Short-lived radioisotopes (26Al 0.73 Ma half life: must accrete fast)
Long-lived radioisotopes (U, Th, K) (slow, only for larger bodies)
Large impacts (only for larger bodies: between Moon and Mars-sized)
Potential energy of core formation (larger bodies: 6300 km radius: 2300°C rise,
Resonant tidal heating (Only moons: Moon?, Titan, Io, Europa)
3000 km radius: 600°C rise)
Slide 18
Observations/Inferences:
Rocky inner, icy outer solar system
Asteroid differentiation temperatures heliocentrically distributed
Gross zonal structure within asteroid belt preserved
The Moon had a magma ocean
The solar photosphere has a composition very similar to CI carbonaceous chondrites
Heat source concentrated near Sun?orLonger times to accrete object farther from the sun (less 26Al heating)?
Slide 19
Two Possible Mechanisms to Separate Metal from Silicate
Porous Flow Immiscible Liquids and Deformation
Slide 20
Dihedral (wetting) Angle Theory
The Dihedral Angle Theta is a force balance between interfacial energies
Slide 21
Sulfide Melt in an Olivine Matrix
Most Fe-Ni-S melts do not form interconnected melt channels
Slide 22
Samples Recording Planetary Differentiation
4.4
Earliest Solar System Solids (CAIs, Chondrules)
Other Plantary Bodies
Earth's Moon
Earth
2.5 0.10.6Time before present (Ga)
Formation (4.56 Ga)
Chondrite alteration
Achondrites (Vesta and HEDs)
Mars (SNCs)
Highlands
Mare Basalts
Continental Crust
Ocean Crust
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Pallasites: Asteroid Core-Mantle Boundary
Brenham
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Short Lived Isotopes: Early Solar System
Gilmore (2002) Science
Slide 25
Victoria and Barringer Craters
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LEW86010; silicate differentiation reference (4558 ± 0.5 Ma) Core segregation (4556 ± 1 Ma)
Silicate differentiation (4526 ± 21 Ma)ALH84001 (4500 ± 130 Ma)
Gov. Valad. (1370 ± 20 Ma)
Lafayette (1320 ± 50 Ma)Y000593 (1310 ± 30 Ma)NWA998 (1290 ± 50 Ma)
Nakhla (1260 ± 70 Ma)Dhofar 019 (575 ± 7 Ma)
DaG 476 (474 ± 11 Ma)
Y980459 (290 ± 40 Ma)QUE94201 (327 ± 10 Ma)NWA1195 (348 ± 19 Ma)
NWA1056 (185 ± 11 Ma)LEW88516 (178 ± 9 Ma)ALH77005 (177 ± 6 Ma)EET79001B (173 ± 3 Ma)Y793605 (173 ± 14 Ma)EET79001A (173 ± 10 Ma)NWA856 (170 ± 19 Ma)LA1 (170 ± 7 Ma)Zagami (169 ± 7 Ma)Shergotty (165 ± 11 Ma)
Chassigny (1362 ± 62)
174 ± 2 Ma
1327 ± 39 Ma
332 ± 9 Ma
Carbonates ALH84001 (3929 ± 37 Ma)
Salts shergottites (0-175 Ma)Iddingsite nakhlites (633 ± 23 Ma)
Borg & Drake
0 1000 2000 3000 4000 4657
Age (Ma)
CAI (solar system formation reference) (4567 ± 0.6 Ma)
Ages of Dated Martian Events
Slide 27
Old Lunar Highland Crust
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Warren Lunar Magma Ocean
Paul Warren
Slide 29
An Oblique Collision between the proto-Earth and a Mars-sized impactor
4.2 minutes
8.4 minutes 12.5 minutes
Kipp and Melosh (86), Tonks and Melosh (93)
Slide 30
Giant Impact during Accretion
Don Davis artwork
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Lunar Assembly outside Roche Limit
Slide 32
Lower Mantle Solidus
Pressure (GPa)
2000
Tem
per
atu
re (
K)
3000
4000
5000
200 40 80 120CMB
Mantle Adiabat
solidus (upper bound) Core T
Multianvil Peridotite Solidus
Olivine shock melting
Magnesiowüstite melting
Zerr et al (98), Holland & Ahrens (97)
Diamond Anvil Peridotite Solidus
Slide 33
0
Depthkm
PressureGPa
500
750
250
15
22.5
0
7.5
PressureGPa
after Carlson, 1994
No Crystal Settling
Perovskite SettlingLow Mg/Si
Dunite High Mg/Si
Liquid
Liquid
Liquid
15
22.5
0
7.5
Crystal Cummulates
t Quench CrustQuenchCrust
Magma Ocean Crystallization
Cummulates should give a chemical signature
Slide 34
Useful Isotope Systems
Parentnuclide 182Hf146Sm
147Sm176Lu187Re232Th235U238U
Daughternuclide 182W142Nd
143Nd176Hf187Os208Pb207Pb206Pb
Half-life 9 Ma103 Ma
106 Ga35.9 Ga42.2 Ga14.01 Ga0.7038 Ga4.468 Ga
Tracer ratio(daughter/stable)
182W/184W
142Nd/144Nd
143Nd/144Nd176Hf/177Hf
187Os/188Os208Pb/204Pb207Pb/204Pb206Pb/204Pb
Slide 35
Possible sources for chemical evidence of the deep mantle
1) The composition of Archean komatiites
2) The composition of modern plume lavas (Ocean Island Basalts)
3) Lower-mantle inclusions in diamonds?
From Don Francis,McGill University
Slide 36
.
1400
1600
1800
2000
2200
2400
2600
0 5 10 15 20 25 30
L + Maj + Mw
L + MgPv + Mw
Liquidus
Solidus
phase relations after Herzberg and Zhang (1996)Pressure (GPa)
Tem
pera
ture
(°C
)
3.5 Ga (Barberton)
2.7 Ga (Boston Twp, Ont)
2.7 Ga (Munro-type)
0.8 Ga (Gorgona)
Present Mantle Adiabat
KLB peridotite and
komatiite source paths
Slide 37
Hawaii Plume
.
Kilometers10 30200
0
K i l o m e t e r s10
20
30
plagioclase peridotitespinel peridotite
spinel peridotitegarnet peridotite
Mantle
Base of the crust 17 km
Crust
KilaueaMauna LoaRift Zone
Shallow MagmaChambers
Upwelling PlumeSolid State
Slide 38
Fingerprints of the
Residual Assemblage
0.1
1
10Pyrope
60 km
400 km
670 kmNd Sm Lu Hf
Nd Sm Lu Hf
Nd Sm Lu Hf
Nd Sm Lu Hf0.1
1
10Perovskite
0.1
1
10Majorite
0.1
1
10
Cpx
Dmineral
melt
The concentrationOf an element in the mineral over that in the melt
Mineral/Melt Partition Coeficients
Two Parent_Daughter Isotopic Systems
Slide 39
Walker-style Cylindrical Multi-anvil
8 Tungsten carbide Truncated Cubes
Octahedral Assembly
1500 Ton Press Uniaxial Force
Slide 40
Carnegie Multi-anvil Press
Slide 41
Assembly
Slide 42
26 GPa, 2450°C, 20 min, KLB-1 + trace elements
200 micronsDiamond
Backscattered ElectronTopographic Image
Epoxy
(Ion probe pits visible)
Diamond
Slide 43
26 GPa, 2450°C, 20 min, KLB-1 + trace elements
Diamond
Backscattered Electron Composition Image
Epoxy
Diamond
Slide 44
26 GPa, 2450°C, 20 min, KLB-1 + trace elements
Diamond
Epoxy
Diamond
25 microns
Magnesiowüstite
Fe-Mg perovskite
Backscattered Electron Composition Image
Slide 45
Assumptions:
A hot initial Earth (a magma ocean into lower mantle)
A chondritic trace element bulk composition
Constant partition coefficient's (pressure, temperature, composition)
Are signs of magma ocean crystallization present in rocks we can sample?
Slide 46
Composition of the Remaining Melt
Slide 47
Composition of the Remaining Melt
Slide 48
Early Archean Zircons
John Hanchar, GWU
PilbaraCraton,
Australia
CL Image, 5mm field of view
Zircons contain high Hf
contents, and hence preserve
their initial Hf isotopic
ratios
Slide 49
Composition of the Remaining Melt
Slide 50
Composition of the Remaining Melt