Origin of noble gases in the insoluble organic compounds of primitive meteorites Yves Marrocchi Centre de Recherches Pétrographiques et Géochimiques CRPG-CNRS - UPR 2300 - Nancy Institut de Planétologie et d Astrophysique de Grenoble October 13th 2011
The possible origin of noble gases in the insoluble organic compounds of primitive meteorites Yves Marrocchi Centre de Recherches Pétrographiques et Géochimiques CRPG-CNRS - UPR 2300 - Nancy Institut de Planétologie et d Astrophysique de Grenoble October 13th 2011
The noble gas family 4 2 He! outer shell of valence electrons is full: chemically inert 20 10 Ne! van de Walls interactions trace elements 40 18 Ar! 84 36 Kr! 130 : 10-18 to 10-21 mol.g -1 (atto to zeptomoles)! important fractionations between reservoirs 131 54! powerful proxies in geochemistry 2
formation of solar system - astrophysical perspectives molecular clouds 10 5 UA hot cores 1000 UA 3
the solar nebula 250 UA 500 UA 25 UA star (99 %) + accretion disc formation of meteorites Rosetta stone 4
classification of meteorites 500 UA iron meteorite pallasite chondrites achondrites
1 mm the primitive meteorites: chondrites chondrules have never been melted witnesses of the early solar system carbon-rich : up to 3 wt% noble gas-rich 6
noble gases of carbonaceous chondrites 10-7 Concentration (mol.g -1 ) 10-9 10-11 10-13 10-15 Busemann et al., 2000 Ivuana (CI) Orgueil (CI) (CI) Allende (CV3) MORB (CV3) MORB 10-17 4 He 20 Ne 36 Ar 84 Kr 132 several orders of magnitude higher than terrestrial rocks! 7
1 mm Allende What is the noble gas carrier? acid attack by HF/HCl (Lewis et al., 1975) 10-6 acid residue: 0.5-1 % of the starting meteorite acid residue contains almost all the noble gases of the bulk meteorite Concentration (mol.g -1 ) 10-7 10-8 10-9 10-10 10-11 10-12 10-13 Allende (CV3) HF/HCl résidu 10-14 4 He 20 Ne 36 Ar 84 Kr 132 8
1 mm What is the acid residue made of? acid residue organic grains macromolecular network (IOM) chromites spinels 9
The noble gas clan: a window on the universe ( i / 132 ) Ech /( i / 132 ) SW 2.5 2.0 1.5 1.0 -HL nanodiamonds ( i / 132 ) Ech /( i / 132 ) SW 3.0 2.5 2.0 1.5 1.0 0.5 SiC -S 0.5 124 126 128 130 132 134 136 Rapports isotopiques ( i / 132 ) 0 124 126 128 130 132 134 136 Rapports isotopiques ( i / 132 ) presence of stardust in primitives meteorites! (Lewis et al., 1987; Bernatowicz et al., 1987, Amari et al., 1990) do not account for the extremely high noble gas concentration of CC 10
What is the MAIN noble gas carrier? residue! chromites, spinels, amorphous carbon, metal " SiC, nanodiamonds, graphite " HNO 3 (oxydation) - 4 % mass loss" - He & Ne : 10-15%" - Ar, Kr & : 90 %" Phase Q! [Lewis et al., 1975]! Concentration (mol.g -1 ) 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 4 He 20 Ne 36 Ar Allende (CV3) HF/HCl résidu HNO 3 résidu 84 Kr 132 10 118
What is the nature of phase Q? Verchovski et al., 2002 Q is a carbon-rich phase but we do not know what fraction of IOM does Q represent? Q? Q? Q? Q? 12
How to determine the composition of an unknown phase? susceptibility to HNO 3 oxidation closed-system stepped etching (CSSE; Wieler et al., 1991, 1992) acid attack (HNO 3 ) under vacuum at different temperatures 13
Q noble gas characteristics - mostly trapped in a poorly defined organic phase that makes ~ 0.05% of total mass: phase Q (Lewis et al., 1975, Ott et al., 1981) - very high concentration : ( 132 (cc/g) = 4 10-6 vs. 1 10-14 in MORBs) 1 Q/SW (normalized to 132 ) 10-1 10-2 10-3 10-4 10-5 10-6 10-7 Kr Ar He Ne 0 20 40 60 80 100 120 140 mass number Elemental fractionation relative to Solar (Busemann et al., 2000) 14
Isotopic composition of phase Q ( i / 130 ) sam /( i / 130 ) ref 1.1 1.05 1 0.95 0.9 Q/SW 124 126 128 129 130 132 134 136 isotopic ratio ( i / 130 ) [(m 1 2) /(m 2 2) ] 1/2 1.1 1.05 1 0.95 0.9 0.85 r=0.98 Kr 21 22 Ne/ Ne 20 22 Ne/ Ne 36 38 Ar/ Ar 0.8 0.75 3 4 He/ He 0.7 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 P1/SW Q/SW Q- => mass fractionation by 1.3%/amu compared to Solar [Busemann et al., 2000] All noble gases are mass-fractionated relative to Solar [Busemann et al., 2000] 15
Stepwise heating measurements on IOM (not Q) 3 2 1 9 6 3 19.0 18.6 18.2 32 31 30 34 32 30 3 He/ 4 He (* 10-4 ) 20Ne/ 22 Ne 38Ar/ 36 Ar (* 100) 86 kr/ 84 Kr (* 100) 136 / 132 (* 100) common temperature release (He = Ne = Ar = Kr = ) very high temperature release: 1200-1400 C= f (petro. grade) constant isotopic ratios single component for heavy noble gases (Huss et al., 1996) 16
Stepwise heating measurements on IOM (not Q) Hausse T C moyenne relâche" entre les classes de météorites" (CI<LL<L<H)" Hausse T C moyenne avec " degré de métamorphisme" Porteur devient plus résistant" avec métamorphisme" Corrélée avec abondances en gaz " rares"
What is the nature and the origin of phase Q? We do not know because. (i) It has never been possible to separate phase Q from IOM (ii) The relationship between IOM and Q is unclear (Q/IOM = 1? 0.1? 0.01? 10-10?) (iii) Impossible to reproduce the noble gas characteristics in a single laboratory experiment (iv) It is not known if the formation of Q and the trapping of its noble gases are synchronous but 17
we have some useful information Concentration en gaz rares (cm 3 STP.g -1 résidu) 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 [Busemann et al., 2000]" Cold Bokkeveld (CM2) Murchinson (CM2 Grosjana (CV3) Lancé (CO3.4) Allende (CV3) Isna (CO3.7) Chainpur (LL3.4) Dimmitt (H3.7) Orgueil (CI) He Ne Ar Kr 1- homogeneous reservoir [Huss et al., 1996]" 2- common process [Busemann et al., 2000] " 18
How NOT to reproduce Q-gases? (1) 3 2 1 3 He/ 4 He (* 10-4 ) 9 6 3 20Ne/ 22 Ne 19.0 18.6 18.2 32 31 30 34 32 30 38Ar/ 36 Ar (* 100) 86 kr/ 84 Kr (* 100) 136 / 132 (* 100) mechanical trapping? should induce different temperature releases (linked to diffusion: He < Ar < ) impossible to reproduce the high temperature release 19
How NOT to reproduce Q-gases? (2) 3 2 1 3 He/ 4 He (* 10-4 ) 9 6 3 20Ne/ 22 Ne 19.0 18.6 18.2 32 31 30 34 32 30 38Ar/ 36 Ar (* 100) 86 kr/ 84 Kr (* 100) 136 / 132 (* 100) Ions implantation or sputtering? differential temperature releases (e.g., lunar samples; Frick et al., 1988) variable isotopic composition (e.g., Genesis target; Meshik et al., 2007) 20
How to (maybe) reproduce Q-gases? 40 ev 500 ev adsorption sputtering implantation Noble gas energy Surface equilibrium process does not imply trapping (Marrocchi et al., 2005) Does not induce any measurable isotopic fractionation (Bernatowicz & Podosek, 1986) but adsorption is not a simple process 21
Anomalous adsorption + + - + - + Influence of the presence of defects at the surface (Lightner & Marti, 1974) surface-associated defects It can lead to an important trapping of Kr & (and potentially Ar) (Ligthner & Marti, 1974; Niedermann & Eugster, 1992) Adsorbed noble gases released at high temperature (1300 C) (Ligthner & Marti, 1974) 22
Anomalous adsorption in the presence of NG ions + + - + - + + + + - + - + It can generate an important isotopic fractionation (Hohenberg et al., 2002) ions It has never been tested on organic surfaces 23
Does anomalous adsorption can be at the origin of Q-gases? Tissandier et al., 2002 1- a high noble gas concentration 2- an elemental fractionation (relative to the starting gas) 3- A mass-dependant isotopic fractionation 4- high-gas release temperature (under vacuum) 5- constant isotopic ratio over temperature steps 24
Ionized region ( + / 10-5 ) UV generator Microwave cavity Ionized xenon UV generator Neutral xenon introduction Crucible Anthracite W filament - Air-like introduced at P 10-2 mbar - Energy 0.1 ev characteristic of the adsorption regime - Heating of anthracite at 1200 C during 5 min - 2 deposits recovered : ionized samples Bulk analysis and stepwise heating neutral samples 25
experimental method + + + - + - + + / 10-5 (Marrocchi et al., 2011) 0.1 ev : energy characteristic of the adsorption regime + + - + - + only neutral 26
extraction of xenon from the samples 27
determination of xenon abundance and isotopic composition purification analysis 28
Neutral samples - No isotopic fractionation relative to the starting gas - Peak temperature release between 200 C and 400 C ( i /130) Ech /( i / 130 ) DX 1.10 1.05 1.00 0.95 départ (XD) Neutre/XD 130 (cc.g -1 ) 1 10-5 8 10-6 6 10-6 4 10-6 2 10-6 136 / 130 (a) 221 220 219 218 217 216 136 / 130 0.90 124 126 128 129 130 131 132 134 136 200 400 600 800 1000 215 Rapports isotopiques ( i / 132 ) Temperature ( C) 29
Ionized samples - 130 concentration higher by one order of magnitude - Isotopic fractionation of +1.36%/amu - Peak temperature release 200 C higher - constant isotopic fractionation ( i /130) Ech /( i / 130 ) DX 1.10 1.05 1.00 0.95 départ (XD) Ionisé/SX 130 (cc.g -1 ) 8 10-5 6 10-5 4 10-5 2 10-5 136 / 130 (b) 236 235 234 233 232 231 136 / 130 0.90 124 126 128 129 130 131 132 134 136 Rapports isotopiques ( i / 132 ) 200 400 600 800 1000 1200 Temperature ( C) 30
isotopic composition relative to -Q 1.10 ( i / 130 ) sam /( i / 130 ) ref 1.05 1.00 0.95 0.90 124 Q Ionized Air/SW 126 128 129 130 132 134 (b) 136 isotopic ratio ( i / 130 ) What is the process at the origin a such a fractionation? 31
Gas phase vs. gas-solid interactions? Ab-initio calculations to solve the relativistic Schrodinger-Dirac equation for isotopes (Marrocchi et al., 2011) the difference of first ionization potential for isotopes is 0.00008%/amu isotopic fractionation is not generated in the gas phase constant isotopic ratio not linked to a depth-dependence implantation linked to a surface process anomalous adsorption onto surface-associated defects 32
What is the influence of the presence of defects at the surface? dipole-dipole (1/r 6 ) r + + - + - + dipole-ion (1/r 2 ) induce xenon trapping a constant isotopic ratio over temperature steps but no isotopic fractionation 33
Anomalous adsorption on carbon surface dipole-dipole 1/r 6 + + - + - + dipole-ion 1/r 2 + + + - + - + ion-ion 1/r surface-associated defects chemical trapping via C n with n = 2, 3, 5, 7 or 9; (Wang et al., 2004) Strong influence of the presence of defects 136 C n chemical bounds are favored comparing to 124 C n Isotopic selection due to chemical reactions? 34
What about the abundance of phase Q? + / 10-5 If isotopic fractionation is due only to the interaction of + with the surface and as trapping yield: ions > atoms (factor 10) trapping yield is enhanced by a factor 10 6 we are able to reproduce the abundance of phase Q 35
Conclusions (1) 1- a high noble gas concentration YES 2- an elemental fractionation (relative to the starting gas) Ø NOT TESTED 3- A mass-dependant isotopic fractionation YES 4- high-gas release temperature (under vacuum) NO 5- constant isotopic ratio over temperature steps YES 36
Conclusions (2) - isotopic fractionation was not generated in the gas phase neither by implantation/sputtering processes - isotopic fractionation is likely linked to variation in chemical bounding strengths - (and probably heavy noble gases) was probably trapped in phase Q via anomalous adsorption process - In environment(s) with ionizing conditions - Q-gases have probably a 2-D distribution in IOM - can explain why it seems impossible to isolate Q from IOM 37
Thanks to Bernard Marty (CRPG) Laurent Tissandier (CRPG) Laurent Zimmerman (CRPG) François Robert (MNHN) Peter Reinhardt (Paris VI) Alexander Meshik (Washington University) 38
1 mm Implications of acid attack first isolation of IOM has been performed by the noble gas geochemists! induced two fantastic discoveries Briani, Marrocchi et al., 2009, PNAS
What is the role of ions? dipole-ion (1/r 2 ) + + - + - + + + + - + - + ion-ion (1/r) induce xenon trapping a constant isotopic ratio over temperature steps and a positive isotopic fractionation of 1.36%/amu How to interpret such an isotopic fractionation? 34