Loading...
Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns
Lindgren, Paula Lee, Martin R Sparkes, Robert Greenwood, Richard C Hanna, Romy D Franchi, Ian A Floyd, Cameron Martin, Pierre-Etienne Hamilton, Victoria E
Lindgren, Paula
Lee, Martin R
Sparkes, Robert
Greenwood, Richard C
Hanna, Romy D
Franchi, Ian A
Floyd, Cameron
Martin, Pierre-Etienne
Hamilton, Victoria E
Citations
Altmetric:
Advisors
Editors
Other Contributors
Affiliation
EPub Date
Issue Date
2020-08-25
Submitted Date
2020-04-02
Subject Terms
CM carbonaceous chondrites
Asteroid sample returns
Post-hydration heating
Asteroid sample returns
Post-hydration heating
Collections
Files
Loading...
Published version
Adobe PDF, 4.43 MB
Research Projects
Organizational Units
Journal Issue
Other Titles
Abstract
The CM carbonaceous chondrites have all been aqueously altered, and some of them were subsequently heated in a parent body environment. Here we have sought to understand the impact of short duration heating on a highly aqueously altered CM through laboratory experiments on Allan Hills (ALH) 83100. Unheated ALH 83100 contains 83 volume per cent serpentine within the fine-grained matrix and altered chondrules. The matrix also hosts grains of calcite and dolomite, which are often intergrown with tochilinite, Fe(Ni) sulphides (pyrrhotite, pentlandite), magnetite and organic matter. Some of the magnetite formed by replacement of Fe(Ni) sulphides that were accreted from the nebula. Laboratory heating to 400 C has caused partial dehydroxylation of serpentine and loss of isotopically light oxygen leading to an increase in bulk d18O and fall in D17O. Tochilinite has decomposed to magnetite, whereas carbonates have remained unaltered. With regards to infrared spectroscopy (4000–400 cm 1; 2.5–25 mm), heating to 400 C has resulted in decreased emissivity (increased reflectance), a sharper and more symmetric OH band at 3684 cm 1 (2.71 mm), a broadening of the SiAO stretching band together with movement of its minimum to longer wavenumbers, and a decreasing depth of the MgAOH band (625 cm 1;16mm). The SiAO bending band is unmodified by mild heating. With heating to 800 C the serpentine has fully dehydroxylated and recrystallized to Fo60/70 olivine. Bulk d18O has further increased and D17O decreased. Troilite and pyrrhotite have formed, and recrystallization of pentlandite has produced Fe,Ni metal. Calcite and dolomite were calcined at 700 C and in their place is an un-named Ca-Fe oxysulphide. Heating changes the structural order of organic matter so that Raman spectroscopy of carbon in the 800 C sample shows an increased (D1 + D4) proportional area parameter. The infrared spectrum of the 800 C sample confirms the abundance of Fe-bearing olivine and is very similar to the spectrum of naturally heated stage IV CM Pecora Escarpment 02010. The temperature-related mineralogical, chemical, isotopic and spectroscopic signatures defined in ALH 83100 will help to track the post-hydration thermal histories of carbonaceous chondrite meteorites, and samples returned from the primitive asteroids Ryugu and Bennu.
Citation
Paula Lindgren, Martin R. Lee, Robert Sparkes, Richard C. Greenwood, Romy D. Hanna, Ian A. Franchi, Ashley J. King, Cameron Floyd, Pierre-Etienne Martin, Victoria E. Hamilton, Chris Haberle, Signatures of the post-hydration heating of highly aqueously altered CM carbonaceous chondrites and implications for interpreting asteroid sample returns, Geochimica et Cosmochimica Acta, Volume 289, 2020, Pages 69-92, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2020.08.021.
Publisher
Journal
Research Unit
PubMed ID
PubMed Central ID
Embedded videos
Type
Journal Article
Item Description
Copyright © 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/). The attached file is the published version of the article.
NHM Repository
NHM Repository
Series/Report no.
ISSN
0016-7037
EISSN
1872-9533
ISBN
ISMN
GovDoc
Test Link
License
openAccess