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Pre- Type II SN Nucleosynthesis (s-process)

Pre- Type II SN Nucleosynthesis (s-process). 21 solar mass star. ratio to solar abundance. Rauscher et al. (2002). Type II SN Nucleosynthesis (r-process). 25 solar mass star. Rauscher et al. (2002). Galactic Composition evolution. Chiappini (2004). Nearby Supernova. Knie et al. (2004).

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Pre- Type II SN Nucleosynthesis (s-process)

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  1. Pre- Type II SN Nucleosynthesis (s-process) 21 solar mass star ratio to solar abundance Rauscher et al. (2002)

  2. Type II SN Nucleosynthesis (r-process) 25 solar mass star Rauscher et al. (2002)

  3. Galactic Composition evolution Chiappini (2004)

  4. Nearby Supernova Knie et al. (2004)

  5. Interstellar shocks Clayton (1979)

  6. Silicate Condensation Clayton (1979)

  7. Significant Events 200 mm The oldest crust in today’s oceans is around 0.2 Ga

  8. Wyoming Craton Beartooth Mountains

  9. Rhenium-Osmium System 187Re 187Os Half life of about 42 Billion years The convecting asthenospheric mantle has roughly chondritic ratios, with 187Re 188Os = 0.4 187Os 188Os = 0.127 to 0.129

  10. Rhenium-Osmium System PUM after Shirey and Walker (1998)

  11. Archean+ Mantle Osmium 187Os/188Os Montana Chromites

  12. Timeline for the eastern Beartooth Mts. 3.56 Ga - Lu-Hf zircon age of average Hellroaring Plateau zircons 3.2-3.4Ga - major crust-forming event that yields the dominant zircon population in quartzites 3.1-2.8 Ga - granulite facies metamorphism (M1) (5-7 kbar 750-800ºC) 2.78-2.79 Ga - andesitic magmatism and intrusion of Long Lake granodiorites 2.79-2.74 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 Complex in adjacent Stillwater block 1.3 Ga – Rb-Sr and K-Ar emplacement age of alkali-olivine mafic dikes 774 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)

  13. from Beartooth Highway, Montana Hellroaring Plateau Chromite Mine

  14. A giant magma ocean and separation of the Earths core: constraints on these events from tiny, brief experiments Kilauea, Hawaii, 1200°C Incandescent Bulb, 2500°C Liquidus of Mantle at 700 km

  15. The Earth is differentiated How and When did this occur? Two Sets of Constraints: Physical Mechanisms and Chemical Signatures

  16. Timing of Core formation

  17. Heat Sources: Solar/Magnetic Induction heating (but T-Tauri: Polar Flows) Short-lived radioisotopes 26 ( Al 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, 3000 km radius: 600°C rise) Resonant tidal heating (Only moons: Moon?, Titan, Io, Europa)

  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? or Longer times to accrete object farther from the sun (less 26Al heating)?

  19. Two Possible Mechanisms to Separate Metal from Silicate Porous Flow Immiscible Liquids and Deformation

  20. Dihedral (wetting) Angle Theory The Dihedral Angle Theta is a force balance between interfacial energies

  21. Sulfide Melt in an Olivine Matrix Most Fe-Ni-S melts do not form interconnected melt channels

  22. Samples Recording Planetary Differentiation

  23. Pallasites: Asteroid Core-Mantle Boundary Brenham

  24. Short Lived Isotopes: Early Solar System Gilmore (2002) Science

  25. Victoria and Barringer Craters

  26. Ages of Dated Martian Events Salts shergottites (0-175 Ma) Iddingsite nakhlites (633 ± 23 Ma) Carbonates ALH84001 (3929 ± 37 Ma) Shergotty (165 ± 11 Ma) Zagami (169 ± 7 Ma) LA1 (170 ± 7 Ma) NWA856 (170 ± 19 Ma) 174 ± 2 Ma EET79001A (173 ± 10 Ma) Y793605 (173 ± 14 Ma) EET79001B (173 ± 3 Ma) ALH77005 (177 ± 6 Ma) LEW88516 (178 ± 9 Ma) NWA1056 (185 ± 11 Ma) Y980459 (290 ± 40 Ma) 332 ± 9 Ma QUE94201 (327 ± 10 Ma) NWA1195 (348 ± 19 Ma) DaG 476 (474 ± 11 Ma) Dhofar 019 (575 ± 7 Ma) Nakhla (1260 ± 70 Ma) NWA998 (1290 ± 50 Ma) 1327 ± 39 Ma Y000593 (1310 ± 30 Ma) Lafayette (1320 ± 50 Ma) Chassigny (1362 ± 62) Gov. Valad. (1370 ± 20 Ma) ALH84001 (4500 ± 130 Ma) Silicate differentiation (4526 ± 21 Ma) Core segregation (4556 ± 1 Ma) LEW86010; silicate differentiation reference (4558 ± 0.5 Ma) CAI (solar system formation reference) (4567 ± 0.6 Ma) 0 1000 2000 3000 4000 4657 Age (Ma) Borg & Drake

  27. Old Lunar Highland Crust

  28. Warren Lunar Magma Ocean Paul Warren

  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)

  30. Giant Impact during Accretion Don Davis artwork

  31. Lunar Assembly outside Roche Limit

  32. 5000 ) K ( 4000 e r u t a i l o s r e p 3000 m e T t a b a i d A e l t n a M 2000 0 20 40 80 120 CMB Pressure (GPa) Lower Mantle Solidus Diamond Anvil Peridotite Solidus Olivine shock meltin g g n i t l e m e t i t s ü w o i s ) e d n Core T n g u a o M b r e p p u ( s u d Multianvil Peridotite Solidus Zerr et al (98), Holland & Ahrens (97)

  33. 0 0 t 7.5 7.5 15 15 22.5 22.5 Magma Ocean Crystallization No Crystal Settling Crystal Cummulates 0 Quench Crust Quench Crust Liquid Depth Pressure Pressure km Liquid GPa GPa 250 Dunite High Mg/Si Liquid 500 Perovskite Settling Low Mg/Si 750 Cummulates should give a chemical signature after Carlson, 1994

  34. Useful Isotope Systems Parent nuclide 182Hf 146Sm 147Sm 176Lu 187Re 232Th 235U 238U Daughter nuclide 182W 142Nd 143Nd 176Hf 187Os 208Pb 207Pb 206Pb Tracer ratio (daughter/stable) 182W/184W 142Nd/144Nd 143Nd/144Nd 176Hf/177Hf 187Os/188Os 208Pb/204Pb 207Pb/204Pb 206Pb/204Pb Half-life 9 Ma 103 Ma 106 Ga 35.9 Ga 42.2 Ga 14.01 Ga 0.7038 Ga 4.468 Ga

  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

  36. 2600 2400 2200 2000 1800 1600 1400 0 5 10 15 20 25 30 KLB peridotite andkomatiite source paths L + MgPv + Mw L + Maj + Mw . 3.5 Ga (Barberton) Temperature(°C) Liquidus 2.7 Ga (Boston Twp, Ont) 2.7 Ga (Munro-type) 0.8 Ga (Gorgona) Present Mantle Adiabat Solidus Pressure (GPa) phase relations after Herzberg and Zhang (1996)

  37. Hawaii Plume

  38. 10 1 0.1 Nd Sm Lu Hf 10 1 melt mineral 0.1 Nd Sm Lu Hf D 10 Majorite 1 0.1 Nd Sm Lu Hf 10 Perovskite 1 0.1 Nd Sm Lu Hf Cpx Fingerprints of the Residual Assemblage 60 km Pyrope Two Parent_Daughter Isotopic Systems Mineral/Melt Partition Coeficients 400 km The concentration Of an element in the mineral over that in the melt 670 km

  39. Walker-style Cylindrical Multi-anvil

  40. Carnegie Multi-anvil Press

  41. Assembly

  42. 26 GPa, 2450°C, 20 min, KLB-1 + trace elements (Ion probe pits visible) 200 microns Diamond Diamond Epoxy Backscattered Electron Topographic Image

  43. 26 GPa, 2450°C, 20 min, KLB-1 + trace elements Diamond Diamond Epoxy Backscattered Electron Composition Image

  44. 26 GPa, 2450°C, 20 min, KLB-1 + trace elements 25 micron s Magnesiowüstite Fe-Mg perovskite Diamond Diamond Epoxy Backscattered Electron Composition Image

  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?

  46. Composition of the Remaining Melt

  47. Composition of the Remaining Melt

  48. Early Archean Zircons Zircons contain high Hf contents, and hence preserve their initial Hf isotopic ratios Pilbara Craton, Australia CL Image, 5mm field of view John Hanchar, GWU

  49. Composition of the Remaining Melt

  50. Composition of the Remaining Melt

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