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Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Planet Formation and Evolution: The Solar System and Extrasolar Planets Tübingen 1.-6.3.2009
M. Trieloff University of Heidelberg, Institute of Geosciences, Heidelberg, Germany
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Astrophysical evidence: Observations of protoplanetary discs (extrasolar)
Cometary evidence (early solar system):Hale Bopp (IR observations)Wild-2 dust returned by STARDUST (laboratory analyses)
Meteoritic evidence (early solar system asteroids):Flash heated objects in chondrites: Chondrules and calcium,aluminum rich inclusions (CAIs)
IR spectroscopy of protoplanetary disks: Mg silicates olivine+pyroxene –crystalline fraction higher in inner disks (van Boekel et al. 2004)
40 +- 20% 15 +- 10%
55 +- 25% 10 +- 5%
95 +- 10% 40 +- 15%
Crystalline fractions in some outer disks considerable, similar to solar system cometscomets(Wooden et al., 2000)
Dust processing in disks and radial mixing into outer disks
IR spectroscopy of protoplanetary disks: Mg silicates olivine+pyroxene –crystalline fraction higher in inner disks (van Boekel et al. 2004)
10 +- 5%
40 +- 20%
55 +- 25%
95 +- 10%
Refractory forsterite grain from STARDUST collector
Silicates (Olv, Px, Fs), glass, Fe-Ni sulfide, refractory minerals (An,Di,Sp), CAI: Inti
No phyllosilicates and carbonates in Wild-2 particles
CAI „Inti“
Cometary grains from comet Wild-2 returned by the STARDUST mission
Astrophysical evidence: Observations of protoplanetary discs (extrasolar)
Cometary evidence (early solar system):Hale Bopp (IR observations)Wild-2 dust returned by STARDUST (laboratory analyses)
Meteoritic evidence (early solar system asteroids):Flash heated objects in chondrites: Chondrules and calcium,aluminum rich inclusions (CAIs)
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Indicator:High temperatureprocessing (crystallinity,refractory rich)
Meteorites: Fragments of small bodies in the solar system, the asteroids between Mars and Jupiter
Inferred number of parent bodies is >100 (accretion to full-sized planet inhibited by early Jupiter?!)
Innisfree
Carbonaceous chondrites (CI, CM, CV, CO, …): (mild thermal/aqueous metamorphism)
• Ca,Al-rich inclusions
• Chondrules
AllendeAllende
• Fine grained matrix (volatile rich)
undifferentiated, e.g. preaccretional structures preserved
undifferentiated, e.g. ‘cosmic’ Fe,Ni abundance
<900 K
1800-2000 K
1400-1600 K
Metal abundance of chondrites: Origin from primitive, undifferentiated parent bodiesVariation of oxidation state and metal abundance: Origin from compositionally different parent asteroids
0,0 0,2 0,4 0,6 0,8 1,00,0
0,2
0,4
0,6
0,8
1,0
Solar total iron
EL
(Fe silicate +sulfide
/Si)CI
CI/CM
EH
EL
Ordinary chondrites: H: high FeL: Low FeLL: Low total, low metallic Fe
Enstatite chondrites
Carbonaceous chondrites: named after main memberCI (Ivuna)CM (Mighei)CV (Vigarano)CO (Ornans)
Astrophysical evidence: Observations of protoplanetary discs (extrasolar)
Cometary evidence (early solar system):Hale Bopp (IR observations)Wild-2 dust returned by STARDUST (laboratory analyses)
Meteoritic evidence (early solar system asteroids):Flash heated objects in chondrites: Chondrules and calcium,aluminum rich inclusions (CAIs)
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Indicator:High temperatureprocessing (crystallinity,refractory rich)
High temperature processing of chondrules and CAIs: indicative of radial mixing?
Nuth (2001)
… some models assume the answer is YES
… what about (abundant) chondrules?… fast cooling (100-2000 K / hour; e.g. former melt glass)… local flash heating (shock, lightning, planetary
collisions) in the asteroid belt region?… do chronology and chemical complementarity
allow large scale movements?
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30
Si [wt%]
Mg [wt%]
CV3 Efremovka
matrix
chondrules
enstatite(intermediate Mg)
forsterite(high Mg)
solarMg/Si-ratio
solarMg-, Si-composition
Chemical complementarity of chondrules and matrix in CV chondrites:Exemplified by Mg and Si (J. Wood, P. Bland, H. Palme)
Chemical complementarity of chondrules and matrix in CR chondrites:Exemplified by Mg and Si (J. Wood, P. Bland, H. Palme)
Matrix and chondrules of specific chondrites formed from Mg/Si= solar precursor material, and were not separated (e.g. by radial drift) before chondrite accretion growth timescales short when compared to radial drift timescales
0,04 0,06 0,08 0,10 0,120,6
0,7
0,8
0,9
1,0
1,1
Solar
EH
ELRLLL
H
CRCI
COCM
CK CV
Mg/Si
Al/Si
Earth´s mantle
[% chondrules]
0
401520
3755
CV chondrules
CV matrix
CR matrix
CR chondrules
What about isotope chronology of chondrule formation?
• Ca,Al-rich inclusions
• Chondrules
4567.2± 0.6 Ma (U-Pb-Pb, CV Efremovka; Amelin et al., 2002)
AllendeAllende
4564.7± 0.6 Ma (CR Acfer059; Amelin et al., 2002)
2-3 Ma age difference supported by 26Al-26Mg chronometry
Short-lived nuclides in the early solar system and their half-lives:
26Al 26Mg (0.72 Ma)129I 129Xe (16 Ma)182Hf 182W (9 Ma)53Mn 53Cr (3.7 Ma)244Pu fission (80 Ma) 10Be 10B (1.5 Ma) 41Ca 41K (0.1 Ma) 60Fe 60Ni (1.5 Ma)
… nucleosynthesis in mass-rich stars
… or nuclear reactions due to solar irradiation (10Be)
Trapezium (Orion nebula)
... injected into protoplanetary disks (solar mass)
Radiometric dating Planetesimal heating
5
4
3
2
1
0
L type
CR type
CO type (Kurahashi et al. 2007)
CO type (Kunihiro et al. 2004)
LL type
Chondrule
26
Al-26
Mg ages (Ma after CAIs)
26Al as tool for radiometric dating:26Al-26Mg ages of individual chondrules of different chondritic parent bodies (Kita, Nagahara, Russell, Mostefaoui etc.)
26Al as planetesimal heat source: Extent of heating as a function of 26Al content and accretion time after CAIs
0 1 2 3 40
1
2
3
4
Melting and partial meltingof planetesimals formed within 1,9 Ma
CO (Tmax
=870 K )(Kurahashi et al. 2007)
CR (Tmax
=670 K )
CO (Tmax
=870 K )(Kunihiro et al. 2004)
L (Tmax
=1220 K )
Mean chondrule
26
Al-26
Mg ages (Ma after CAIs)
Parent body formation age predicted by 26Al heating (Ma after CAIs)
LL (Tmax
=1220 K)
Mean 26Al-26Mg ages of chondrules of different chondritic parent bodies correlate with heating degree of parent bodies: stronger heated planetesimals have earlier formed chondrule populations
Astrophysical evidence: Observations of protoplanetary discs (extrasolar)
Cometary evidence (early solar system):Hale Bopp (IR observations)Wild-2 dust returned by STARDUST (laboratory analyses)
Meteoritic evidence (early solar system asteroids):Flash heated objects in chondrites: Chondrules and calcium,aluminum rich inclusions (CAIs)
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Indicator:High temperatureprocessing (crystallinity,refractory rich)
High temperature processing of chondrules: indicative of radial mixing?
High temperature processing of CAIs: indicative of radial mixing?
NO (only possible if fast movement with micron dust)
Fassait (Ti-rich diopside)
Anorthite
Zoned type B1 CAI from Leoville (CV)
Melilite
from: Davis & Richter 2005
Fe-Ni-metal
Enstatite – MgSiO3
Forsterite – Mg2SiO4
Gehlenite Ca2Al2SiO7
Hibonite CaAl12O19
AnorthiteFra
ctio
n C
I ch
ond
riti
c co
mp
osit
ion
con
den
sed
Cpx
Albite
Spl
Condensation sequence of minerals in a cooling solar nebula: Ca,Al minerals important high temperature condensates
CAIs and refractory inclusions:
Rare (0.1% - 13%)Carrier of 16O enrichment in carbonaceous chondritesSlower cooling than chondrules (10 K / hour)Resided 2-4 Ma in solar nebulaIndependent chemical component
Astrophysical evidence: Observations of protoplanetary discs (extrasolar)
Cometary evidence (early solar system):Hale Bopp (IR observations)Wild-2 dust returned by STARDUST (laboratory analyses)
Meteoritic evidence (early solar system asteroids):Flash heated objects in chondrites: Chondrules and calcium,aluminum rich inclusions (CAIs)
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Indicator:High temperatureprocessing (crystallinity,refractory rich)
High temperature processing of chondrules: indicative of radial mixing?
High temperature processing of CAIs: indicative of radial mixing?
NO (only possible if fast movement with micron dust)
Good candidates
Conclusions:
High degree of crystallinity or high temperature processing is not a compelling proof of radial mixing
High temperature processing of CAIs suggests radial outward transport in solar nebula, but reasoning requires broad body of evidence
Future modeling needs to evaluate different mechanisms (meridional flows, etc.) and must check for element fractionations
Radial Mixing in the Early Solar System: Meteoritic and Cometary Evidence
Indicator:High temperatureprocessing (crystallinity,refractory rich)
High temperature processing of chondrules: indicative of radial mixing?
High temperature processing of CAIs: indicative of radial mixing?
NO (only possible if fast movement with micron dust)
Good candidates