Temperatures of aqueous alteration and evidence for methane generation on the parent bodies of the CM chondrites
- Creators
- Guo, Weifu
- Eiler, John M.
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.
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.Additional details
- Eprint ID
- 35562
- DOI
- 10.1016/j.gca.2007.07.029
- Resolver ID
- CaltechAUTHORS:20121120-103623970
- NASA Cosmochemistry Program
- Created
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2012-11-20Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences