Volatiles: Constraints on disk evolution, and planetesimal/planets accretion
Conel M. O’D. Alexander DTM, Carnegie Institution of Washington Meteorites Recorders of first few million years (Ma)
Chondrites
1 cm Achondrites
Irons 4,567.3±0.2 million years old
Formed in <2 Ma Formed in ~2-4 Ma Chondrites – ‘cosmic’ sediments
Allende (CV3) Three basic components: Chondrules, CAIs, Matrix.
Lancé (CO3)
~2 cm Enstatite – EH, EL Ordinary – H, L, LL (and R)
Carbonaceous – CI, CM, CR, CV, CO, CK
Photomicrographs Courtesy Adrian Brearley ~2 cm Time constraints – Asteroids-Mars
0 t0=4,567 Ma (Connelly et al. 2012)
ProtoJupiter = 20 M Vesta (HEDs) earth 1
Formation of angrite parent body Mars (~50%) Formation of E chondrites 2 Formation of O+R chondrites Formation of CK chondrites Formation of CV+CO chondrites
3 Time after CV (Ma) CAIsTime after Formation of CI, CM+TL chondrites 26 4 Formation of CR chondrites Al no longer an effective heat source Dissipation of the gas disk (and Grand Tack?) Time constraints - Earth t0=4,567 Myr (Connelly et al. 2012)
0 Jupiter reaches 20 Mearth? Dissipation of gas disk (and Grand Tack?)
10
Debris disk 20
30
Retention of atmosphere 40
Time after CV (Ma) CAIs Timeafter (Avice and Marty 2014)
50
Formation of the Moon (Touboul et al. 2007; Barboni et al. 2017) Time constraints - Earth
0 4,567 Ma (Connelly et al. 2012)
Retention of atmosphere 50 (Avice and Marty, 2014)
Formation of the Moon 100 (Touboul et al. 2007)
150 Evidence for oceans from oldest zircons (Wilde et al. 2001)
200 Time after Solar System formation (Ma) formation System Solar Timeafter What did the Earth accrete and when was it accreted? Asteroids and Comets
1100 Comets JFC
900 JFC – Jupiter Family Earth (Comets – H from H2O, OCC OCC - Oort Cloud 700 N from HCN/NH3)
500
300
N N (‰) CR 15
d CM 100 TL Earth Venus -100 CI Mars -300 Solar -500 -1000 -500 0 500 1000 1500 d(‰)=(R/Rstd-1)x1000 dD (‰) R=D/H or 15N/14N Marty et al. (2016) – cometary contributions to H-C-N were minor, but may have been important for noble gases. Earth’s siderophile isotopes
All inconsistent with carbonaceous chondrites
Earth Earth
Earth
Of the carbonaceous chondrites, the CIs are closest to the Earth’s composition.
Nevertheless, if CI-like material was the source of the volatiles, it must have accreted before the end of core formation – assumed to be Moon-formation.
The late veneer after Moon-formation was too little and too dry. Atmosphere ≠ interior
Péron et al. (2017)
Mantle Ne – Solar or implanted solar wind (and H & He?)
Either the atmosphere was not degassed from the interior, or the interior/atmosphere compositions have change after degassing? Did early planetesimals fully degas?
1100
JFC
900 Earth OCC 700
500
300
N N (‰) CR 15
d CM 100 Angrite TL Earth Venus -100 Vesta CI Mars -300 Solar (Miura & Sugiura 1993; Abernethy et al. 2013; Sarafian et al. 2014,2017; Barrett et al. 2016) -500 -1000 -500 0 500 1000 1500 dD (‰) Crystallization ages Accretion ages of CIs and CMs Angrite D’Orbigny ~3.5 Ma after CAIs ~3.5 Ma after CAIs (Fujiya et al. 2013) HED Stannern ~3.6 Ma after CAIs Where did the carbonaceous chondrites form? Trouble with Saturn’s moons
ISM ices
Enceladus
H2O Comets
Earth
Titan – CH4
Bulk solar Yang et al. (2013) 4000 Chondritic H is 3500 3000
a mix of H2O 2500 Organics
2000 D (‰) and organics d 1500 1000 500 0 -500 0 5 10 15 20 25 900 C/H (wt.) 700 CR
500 Tagish Lake
300 D (‰) D CR water d 100 CI
Bulk Bulk -100 CM -300 CM water -500 0 2 4 6 (Alexander et al. 2012) Bulk C/H (wt.) Chondritic water was not from the outer Solar System ? 1.E-03 4000 Oort Cloud comets 3000 Enceladus RC 2000
JFC 1000 OC
0 d
Earth (‰) D CR -200
1.E-04 -400
D/H Ratio D/H CM CO -600 CI Tagish Lake -800
Protosolar
1.E-05
After Alexander et al. (2012) 3Fe + 4H2O = Fe3O4 + 4H2
12000 Rayleigh fractionation
10000
O 0°C 2 8000
6000 ) of residual ) H of residual 200°C
(‰ 4000
D d
2000
0 0.01 0.1 1
Fraction of H2O remaining
(Alexander et al. 2010) H isotopes: Indicators of formation distance?
1.0E-03 Comets Enceladus
Saturn
GT
Earth
1.0E-04 Titan JFCs (CH ) OCCs LL CR 4 D/H in Water in D/H CM CI Chondrites
Solar
1.0E-05 0.1 1 10 100 Distance (AU) Summary • All chondrites accreted their volatiles in a ~CI-like matrix. C, N, noble gases and some H was in a macromolecular organic matter. H2O was accreted as ice that also included CO2 and HCN/NH3. No chondrite seems to have accreted their full solar H2O complement.
• The initial D/H of water in CCs and non-CCs were not very different, contrary to model expectations, and less than Enceladus or even Titan.
• From these perspectives, there are no compelling reasons for the CCs to have formed in outer Solar System, or at least not beyond the location of Saturn when its moons formed (3-7 AU in the Grand Tack).
• CI/CM-like material was the major source of terrestrial planet H+N+C, perhaps with some solar input, but comets may have been much more important for noble gases.
• Atmospheric volatiles were accreted before Moon-formation and may not have been initially stored in the Earth’s interior, yet somehow they survived impacts large and small. Roughly chondritic volatiles
1.0E-01 10-1 Cs Pb Kr Cl Cd 36Ar H 2-4% CI/CM C like material
Ne
1.0E-02 10-2 I Br Late Veneer
Gradual Xe loss Xe (Pujol et al. 2011)? 1.0E-03-3
BulkEarth/CI 10 Hidden N reservoir or impact loss?
(Dereulle et al., 1992; Marty, 2012; Palme and O’Neill, 2014) 1.0E-0410-4 0 2 4 6 8 10 12 14 N isotopes: Indicators of formation distance?
0.008 Comet HCN/NH3 (averages) 0.007 Titan
0.006 Saturn
GT
N
14 0.005 Chondrites N/
(bulks) AminoAcids 15
0.004
Earth
0.003 Solar 0.002 0.1 1 10 100 Distance (AU)
Strecker-cyano synthesis R-C=O + HCN + NH3 + H2O = R-CNH2-COOH ’Twin’ planets are not identical
1.0E+01 Comets or Ne Solar wind? 36Ar 1.0E+00
Kr 1.0E-01 40Ar
1.0E-02
Venus/CI Xe N C 1.0E-03
1.0E-04 1.0E-04 1.0E-03 1.0E-02 1.0E-01 1.0E+00 1.0E+01 Earth/CI
Venus abundances just for atmosphere Volatiles in matrix
2.5 Bulk CV chondrites
2.0
1.5
1.0 Abundance/CI Lithophiles 0.5 Siderophiles Matrix Chalcophiles 0.0 500 1000 1500 2000 50% Condensation Temperature (K)
(Wasson and Kallemeyn, 1988) Volatiles in matrix
350 CI 300 TL 250 CC CM 200 Non-CC
150 RC Bulk (ppm) Zn Bulk 100 CO,CV,CR OC 50
0 0 20 40 60 80 100 Matrix (vol.%)
(Wasson and Kallemeyn, 1988; Rubin and Wasson 1993: Brown et al. 2000) Volatiles in matrix
4.5 4.0 TL CI
3.5
3.0 2.5 CM 2.0
1.5 CO,CV,CR Bulk Bulk (wt.%) C
1.0 OC 0.5 0.0 0 20 40 60 80 100 Matrix (vol.%)
(Alexander et al. 2012,2014) Presolar grains in matrix (Xe-HL carried by supernova nanodiamonds)
2.5
CI
2.0
cc/g)
10 - 1.5 CM CV
Xe HL (10 HL Xe 1.0
132 CO,CR
0.5 Bulk Bulk OC
0.0 0 20 40 60 80 100 Matrix (vol.%)
(Huss and Lewis 1995; Huss et al. 2003) Volatiles in matrix
1.8
1.6 CI
1.4
1.2 CM 1.0 TL 0.8
0.6 CO, CR Bulk Bulk (wt.%) H 0.4 CV 0.2 OC 0.0 0 20 40 60 80 100 Matrix (vol.%)
(Alexander et al. 2012) Story so far • The abundances of highly volatile elements, organic C, presolar circumstellar grains and water suggest that matrices in ALL chondrites are dominated by ~CI-like material.
• If correct, since the ECs, OCs & RCs all formed ~2 Ma after CAIs: (1) CI-like material was present in the inner Solar System >2 Ma before a possible Grand Tack, and ~1 Ma after the inner Solar System was possibly sealed off by a growing Jupiter. (2) The snowline was already in the inner Solar System by 2 Ma. The main building blocks of the terrestrial planets may not have been initially volatile-free, but if formed <3-3.5 Ma after CAIs they were heavily modified by internal heating due to 26Al. D/H in H2O: an indicator of formation distance from the Sun?
Interstellar
H2O
H2
Enceladus
/(D/H) Comets H2O
(D/H) Earth
Turbulent mixing
High T H2O Solar Horner et al. (2007) Distance from the Sun (AU) Rosetta results
<10% to >90% of terrestrial 36Ar may be cometary (Marty et al. 2016)
22±5% of Xe from comets (Marty et al. 2017) Not primordial atmospheres
1100
900 Earth
700
500
300
N N (‰)
15 d 100 Mars Earth Venus -100
-300 Solar -500 -1000 -500 0 500 1000 1500
dD (‰) d(‰)=(R/Rstd-1)x1000 R=D/H or 15N/14N Jaupart et al. (2017) – Ne, at least, in embryos not from primordial atmospheres. Corrected water H isotopes
1.E-0310-3 4000 Oort Cloud comets RC 3000
2000 Enceladus
JFC 1000 Ratio Earth 0 d -200 (‰) D -4
1.E-0410 -400
CR LL -600
CI CM Water D/H D/H Water -800
Protosolar
1.E-0510-5
(Sutton et al. 2017) H isotopes: Indicators of formation distance?
1.0E-03 Comets Enceladus
Saturn
GT
Earth
1.0E-04 Titan
JFCs OCCs (CH4)
D/H in Water in D/H Chondrites
Solar
1.0E-05 0.1 1 10 100 Distance (AU) A possible alternative?
• There was a burst of early planetesimal formation involving material that had been thermally processed by FU Orionis outbursts and from which CAI material was extracted. • By 2 Ma this material was nearly exhausted and material from the outer Solar System (matrix) began diffusing in and dominated later formed planetesimals. This material included refractory inclusions (CAIs and AOAs). Accretion times and water contents Clearing of inner disk? Differentiated Lithified Grand Tack?
3.5 Wet3 CI CM 2.5 CR 2 CK CV Damp O,R 1.5 ? CO 1 Now Dry Dry0.5 E
Water content on accretion content Water 0 1 1.5 2 2.5 3 3.5 4 Accretion time (Ma) after CAIs
Accretion times modified after Sugiura and Fujiya (2014) Summary
4
CR (Ma)
3
CV OC 26Al OC 182Hf 2 age after CAI ageafter CO CO OC CV 26Al CV 182Hf
1 CR Mean chondrule Meanchondrule 0 0 1 2 3 4 Accretion age after CAI (Ma) Accretion ages: Sugiura and Fujiya (2014) Chondrule ages: OC Al-Mg, Kita et al. 2008, Villeneuve et al. 2009; OC Hf-W, Kleine et al. 2008; CO Al-Mg, Kurahashi et al. 2008; CV Al-Mg (Kaba) Nagashima et al. 2015; CV Hf-W Budde et al. 2016; CR Al-Mg Schrader et al. 2017. Volatiles from primitive meteorites
Marty et al. (2012, 2013) Asteroidal Sources
Bus and Binzel (2002) Hsieh and Jewitt (2006)
C-complex≈CC
S-complex≈OC+RC
Hungaria≈EC
Warren (2011) D/H in Solar System objects
Comets
Altwegg et al. (2015) Volatiles from primitive meteorites
help
Marty et al. (2013) Time constraints
0 4,567 Myr (Connelly et al. 2012)
)
Myr Retention of atmosphere 50 (Avice and Marty, 2014)
Formation of the Moon 100 (Touboul et al. 2007)
150 Evidence for oceans from oldest zircons (Wilde et al. 2001)
200 Time after Solar System formation ( formation System Solar Timeafter 1100 Comets JFC
900 JFC – Jupiter Family Earth (Comets – H from H2O, OCC OCC - Oort Cloud 700 N from HCN/NH3)
500
300
N N (‰) CR 15
d CM 100 Angrite TL Earth
-100 CI Vesta Mars -300 Moon Solar -500 -1000 -500 0 500 1000 1500 dD (‰) What’s the issue?
• There was CI/CM-like material in the inner Solar System well before there could have been a Grand Tack (>4 Ma), but after Jupiter may have sealed off the inner Solar System (≤1 Ma).
• Minor irritant or big problem? Depends on how much and how much earlier.