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Temperatures of aqueous alteration and evidence for methane generation on the parent bodies of the CM chondrites

Guo, Weifu and Eiler, John M. (2007) Temperatures of aqueous alteration and evidence for methane generation on the parent bodies of the CM chondrites. Geochimica et Cosmochimica Acta, 71 (22). pp. 5565-5575. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20121120-103623970

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Abstract

Aqueous alteration of primitive meteorites was among the earliest geological processes during the evolution of our solar system. 'Clumped-isotope' thermometry of carbonates in the CM chondrites, Cold Bokkeveld, Murray, and Murchison, demonstrates that they underwent aqueous alteration at 20–71 °C from a fluid with δ^(18)O_(VSMOW) of 2.0‰ to 8.1‰ and δ^(17)O_(VSMOW) of −0.1‰ to 3.0‰. The δ^(13)C_(VPDB) values of these carbonates exhibit a negative correlation with the δ^(18)O_(VSMOW) of their formation waters, consistent with formation and escape of ^(13)C-depleted CH_4 during aqueous alteration. Methane generation under these conditions implies that the alteration fluid was characterized by an Eh ⩽ −0.67 and pH ⩾ 12.5 (or lower at the highest alteration temperatures). Our findings suggest that methane generation may have been a widespread consequence of planetesimal and planetary aqueous alteration, perhaps explaining the occurrence of methane on Titan, Triton, Pluto, and other Kuiper-belt objects.


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http://dx.doi.org/10.1016/j.gca.2007.07.029DOIUNSPECIFIED
http://www.sciencedirect.com/science/article/pii/S0016703707004383PublisherUNSPECIFIED
Additional Information:© 2007 Elsevier Ltd. Received 10 October 2006; accepted in revised form 16 July 2007; available onilne 11 September 2007. Associate editor: Sara S. Russell. This research was supported by a grant to J.M.E. from the NASA Cosmochemistry Program. We thank Sara Russell for her editorial handling of this manuscript, and Chris Romanek and two anonymous reviewers for thoughtful and constructive comments.
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NASA Cosmochemistry ProgramUNSPECIFIED
Issue or Number:22
Record Number:CaltechAUTHORS:20121120-103623970
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20121120-103623970
Official Citation:Weifu Guo, John M. Eiler, Temperatures of aqueous alteration and evidence for methane generation on the parent bodies of the CM chondrites, Geochimica et Cosmochimica Acta, Volume 71, Issue 22, 15 November 2007, Pages 5565-5575, ISSN 0016-7037, 10.1016/j.gca.2007.07.029. (http://www.sciencedirect.com/science/article/pii/S0016703707004383)
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ID Code:35562
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:20 Nov 2012 18:50
Last Modified:03 Oct 2019 04:29

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