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)

Slide 2

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

Slide 23

Pallasites: Asteroid Core-Mantle Boundary

Brenham

Slide 24

Short Lived Isotopes: Early Solar System

Gilmore (2002) Science

Slide 25

Victoria and Barringer Craters

Slide 26

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

Slide 28

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

Slide 31

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