Franchi, I.A.

Lee, M.R.

Lindgren, P.

Mark, D.F.

Sofe, M.

Starkey, N.A.

English

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      Lindgren, P., Sofe, M., Starkey, N.A., Franchi, I.A., Mark, D.F., and Lee, M.R. (2013) Tracking the oxygen isotope evolution of aqueous solutions during alteration of CM2 carbonaceous chondrites. In: 76th Annual Meeting of the Meteoritical Society, 29 Jul - 2 Aug 2013, Edmonton, AB, Canada.    Copyright © 2013 The Authors   A copy can be downloaded for personal non-commercial research or study, without prior permission or charge  Content must not be changed in any way or reproduced in any format or medium without the formal permission of the copyright holder(s)   When referring to this work, full bibliographic details must be given    http://eprints.gla.ac.uk/81873   Deposited on: 03 July 2013                   Enlighten – Research publications by members of the University of Glasgow http://eprints.gla.ac.uk TRACKING THE OXYGEN ISOTOPE EVOLUTION OF AQUEOUS SOLUTIONS DURING ALTERATION OF CM2 CARBONACEOUS CHONDRITES.  P. Lindgren1, M. R. Sofe1, N. A. Starkey2, I. A. Franchi2, D. F. Mark3, and M. R. Lee1. 1School of Geographical and Earth Sci-ences, University of Glasgow, Glasgow G12 8QQ, U.K. E-mail: Paula.Lindgren@Glasgow.ac.uk. 2Planetary & Space Sciences, The Open University, Milton Keynes, MK7 6AA, U.K. 3Scottish Universities Environmental Research Centre, East Kilbride, G75 OQF, U.K.  Introduction: The oxygen isotope compositions of carbonate minerals that formed during aqueous alteration of CM2 carbona-ceous chondrites can provide valuable information on the nature and intensity of fluid-rock interaction, relative mineralization timescales and crystallization temperatures, e.g. [1-3]. Analysis of bulk samples shows that 18O and ∆17O values differ between CMs [1], and recent ion microprobe work has revealed that indi-vidual meteorites can contain populations of grains with very dif-ferent 18O and 17O values [4]. Taken together, these findings suggest that the isotopic composition and/or temperature of par-ent body aqueous solutions varied spatially and/or temporally over sub-meteorite and greater length scales. Here we have sought to investigate further the dynamics of the aqueous system by oxygen isotope analysis of three distinct generations of Ca-carbonate minerals in the LON 94101 CM2 carbonaceous chondrite. Methods: This study used one thin section of LON 94101, whose carbonate grains were located and imaged using a FEI Quanta 200F field-emission SEM. These grains were then ana-lysed using a NanoSIMS 50L at the Open University (U.K). Analyses were performed in spot mode and with a ~30pA Cs+ ion beam; 16O was measured on a Faraday cup and 17O and 18O using electron multipliers. Results and discussion: LON 94101 contains three genera-tions of Ca-carbonate: (i) 5-100 micrometer sized grains of arag-onite, (ii) 10-50 micrometer sized grains of calcite, and (iii) a millimeter-sized calcite vein [5]. The aragonite is inferred to have crystallized first (mean 18O 39.9±0.6‰, ∆17O -0.3±1.0‰, 1σ) and was followed by calcite grains (mean 18O 37.5±0.7‰, ∆17O 1.4±1.1‰, 1σ), then the calcite vein (mean 18O 18.4±0.3‰, ∆17O -0.5±0.5‰, 1σ). NanoSIMS data suggest that the calcite grains precipitated shortly after aragonite and from solutions of a similar oxygen isotope value and/or temperature. The calcite vein formed following brittle fracturing of the parent body in response to an impact [5], and from aqueous solutions of very different oxygen isotope value and/or temperature. Taken together, these results indicate that the region of the parent body sampled by LON 94101 was exposed to at least two generations of aqueous solutions. Those that formed the vein calcite were sourced from a different parent body region and entered LON 94101 via a high permeability fracture network. References: [1] Benedix G. K. et al. 2003. Geochimica et Cosmochimica Acta 67:1577–1588. [2] Guo W. and Eiler J. M. 2007. Geochimica et Cosmochimica Acta 71:5565–5575. [3] Clayton R. N. and Mayeda T. K. 1984. Earth and Planetary Science Letters 67:151–161. [4] Tyra M. A. et al. 2012. Geochimica et Cosmochimica Acta 77:383–395. [5] Lindgren P. et al. 2011. Earth and Planetary Science Letters 306:289–298. Acknowledgements: We are grateful to the NASA Antarctic meteorite collection for loan of the LON 94101 thin section and to UKCAN for access to the Open University NanoSIMS. 5111.pdf76th Annual Meteoritical Society Meeting (2013)

Tracking the oxygen isotope evolution of aqueous solutions during alteration of CM2 carbonaceous chondrites

Enlighten: Publications

  
 
 
 
 
Lindgren, P., Sofe, M., Starkey, N.A., Franchi, I.A., Mark, D.F., and Lee, 
M.R. (2013) Tracking the oxygen isotope evolution of aqueous solutions 
during alteration of CM2 carbonaceous chondrites. In: 76th Annual Meeting 
of the Meteoritical Society, 29 Jul - 2 Aug 2013, Edmonton, AB, Canada. 
 
 
 
Copyright © 2013 The Authors 
 
 
A copy can be downloaded for personal non-commercial research or 
study, without prior permission or charge 
 
Content must not be changed in any way or reproduced in any format 
or medium without the formal permission of the copyright holder(s) 
 
 
When referring to this work, full bibliographic details must be given 
 
 
 
http://eprints.gla.ac.uk/81873 
 
 
Deposited on: 03 July 2013 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Enlighten – Research publications by members of the University of Glasgow 
http://eprints.gla.ac.uk 
TRACKING THE OXYGEN ISOTOPE EVOLUTION OF 
AQUEOUS SOLUTIONS DURING ALTERATION OF CM2 
CARBONACEOUS CHONDRITES.  
P. Lindgren1, M. R. Sofe1, N. A. Starkey2, I. A. Franchi2, D. F. 
Mark3, and M. R. Lee1. 1School of Geographical and Earth Sci-
ences, University of Glasgow, Glasgow G12 8QQ, U.K. E-mail: 
Paula.Lindgren@Glasgow.ac.uk. 2Planetary & Space Sciences, 
The Open University, Milton Keynes, MK7 6AA, U.K. 3Scottish 
Universities Environmental Research Centre, East Kilbride, G75 
OQF, U.K. 
 
Introduction: The oxygen isotope compositions of carbonate 
minerals that formed during aqueous alteration of CM2 carbona-
ceous chondrites can provide valuable information on the nature 
and intensity of fluid-rock interaction, relative mineralization 
timescales and crystallization temperatures, e.g. [1-3]. Analysis 
of bulk samples shows that 18O and ∆17O values differ between 
CMs [1], and recent ion microprobe work has revealed that indi-
vidual meteorites can contain populations of grains with very dif-
ferent 18O and 17O values [4]. Taken together, these findings 
suggest that the isotopic composition and/or temperature of par-
ent body aqueous solutions varied spatially and/or temporally 
over sub-meteorite and greater length scales. Here we have 
sought to investigate further the dynamics of the aqueous system 
by oxygen isotope analysis of three distinct generations of Ca-
carbonate minerals in the LON 94101 CM2 carbonaceous 
chondrite. 
Methods: This study used one thin section of LON 94101, 
whose carbonate grains were located and imaged using a FEI 
Quanta 200F field-emission SEM. These grains were then ana-
lysed using a NanoSIMS 50L at the Open University (U.K). 
Analyses were performed in spot mode and with a ~30pA Cs+ ion 
beam; 16O was measured on a Faraday cup and 17O and 18O using 
electron multipliers. 
Results and discussion: LON 94101 contains three genera-
tions of Ca-carbonate: (i) 5-100 micrometer sized grains of arag-
onite, (ii) 10-50 micrometer sized grains of calcite, and (iii) a 
millimeter-sized calcite vein [5]. The aragonite is inferred to have 
crystallized first (mean 18O 39.9±0.6‰, ∆17O -0.3±1.0‰, 1σ) 
and was followed by calcite grains (mean 18O 37.5±0.7‰, ∆17O 
1.4±1.1‰, 1σ), then the calcite vein (mean 18O 18.4±0.3‰, 
∆17O -0.5±0.5‰, 1σ). NanoSIMS data suggest that the calcite 
grains precipitated shortly after aragonite and from solutions of a 
similar oxygen isotope value and/or temperature. The calcite vein 
formed following brittle fracturing of the parent body in response 
to an impact [5], and from aqueous solutions of very different 
oxygen isotope value and/or temperature. Taken together, these 
results indicate that the region of the parent body sampled by 
LON 94101 was exposed to at least two generations of aqueous 
solutions. Those that formed the vein calcite were sourced from a 
different parent body region and entered LON 94101 via a high 
permeability fracture network. 
References: [1] Benedix G. K. et al. 2003. Geochimica et 
Cosmochimica Acta 67:1577–1588. [2] Guo W. and Eiler J. M. 
2007. Geochimica et Cosmochimica Acta 71:5565–5575. 
[3] Clayton R. N. and Mayeda T. K. 1984. Earth and Planetary 
Science Letters 67:151–161. [4] Tyra M. A. et al. 2012. 
Geochimica et Cosmochimica Acta 77:383–395. [5] Lindgren P. 
et al. 2011. Earth and Planetary Science Letters 306:289–298. 
Acknowledgements: We are grateful to the NASA Antarctic 
meteorite collection for loan of the LON 94101 thin section and 
to UKCAN for access to the Open University NanoSIMS. 
5111.pdf76th Annual Meteoritical Society Meeting (2013)


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Tracking the oxygen isotope evolution of aqueous solutions during alteration of CM2 carbonaceous chondrites

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