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Experimental constraints on the stable-isotope systematics of CO_2 ice/vapor systems and relevance to the study of Mars

Eiler, John M. and Kitchen, Nami and Rahn, Thom A. (2000) Experimental constraints on the stable-isotope systematics of CO_2 ice/vapor systems and relevance to the study of Mars. Geochimica et Cosmochimica Acta, 64 (4). pp. 733-746. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20121023-142705471

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Abstract

Variations in the isotopic compositions of oxygen, hydrogen, and carbon in the near-surface environment of Mars are likely influenced by condensation, evaporation, and sublimation of major volatile species (H_2O, CO_2). We present here an experimental study of the fractionations of ^(18)O/^(16)O and ^(13)C/^(12)C ratios between CO_2 ice and vapor at conditions relevant to the present near-surface of Mars; these experiments constrain isotopic variations generated by the current Martian CO_2 condensation/sublimation cycle. Oxygen-isotope fractionation between ice and vapor (Δ_(ice-vapor) = 1000 · 1n ([^(18)O_(ice)/^(16)O_(ice)] / [^(18)O_(vapor)/^(16)O_(vapor)]) varies approximately linearly vs. 1/T between temperatures of 150 and 130 K (from 4.2 and 7.5 ‰, respectively). Carbon isotopes are unfractionated (Δ^(13)C_(ice-vapor) ≤ 0.2‰) at temperatures ≥ 135 K and only modestly fractionated (Δ^(13)C_(ice-vapor) ≤ 0.4‰) at temperatures between 135 and 130 K. Martian atmospheric volumes that are residual to high extents of condensation (i.e., at high latitudes during the winter) may vary in δ^(18)O by up to tens of per mil, depending on the scales and mechanisms of ice/vapor interaction and atmospheric mixing. Precise (i.e., per mil level) examination of the Martian atmosphere or ices could be used as a tool for examining the Martian climate; at present such precision is only likely to be had from laboratory study of returned samples or substantial advances in the performance of mass spectrometers on landers and/or orbital spacecraft. Oxygen-isotope fractionations accompanying the CO_2 condensation/sublimation cycle may play a significant role in the oxygen-isotope geochemistry of secondary phases formed in SNC meteorites, in particular as a means of generating ^(18)O-depleted volatile reservoirs.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/S0016-7037(99)00327-0DOIUNSPECIFIED
http://www.sciencedirect.com/science/article/pii/S0016703799003270PublisherUNSPECIFIED
Additional Information:© 1999 Elsevier Science Ltd. Received May 20, 1998; accepted in revised form August 9, 1999. This paper was improved by formal reviews from Bob Clayton, Dave Paige, and one anonymous reviewer and by additional helpful reviews from and discussion with Andy Ingersoll, Bruce Jakosky, Bruce Murray, Mark Richardson, Hugh Taylor, and Yuk Yung. We also gratefully acknowledge the assistance of Altair Maine in some experiments described in this paper.
Issue or Number:4
Record Number:CaltechAUTHORS:20121023-142705471
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121023-142705471
Official Citation:John M Eiler, Nami Kitchen, Thom A Rahn, Experimental constraints on the stable-isotope systematics of CO2 ice/vapor systems and relevance to the study of Mars, Geochimica et Cosmochimica Acta, Volume 64, Issue 4, February 2000, Pages 733-746, ISSN 0016-7037, 10.1016/S0016-7037(99)00327-0. (http://www.sciencedirect.com/science/article/pii/S0016703799003270)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35045
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:23 Oct 2012 21:51
Last Modified:03 Oct 2019 04:24

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