Thermal Alteration of Labile Elements in Carbonaceous Chondrites

1Alessondra Springmann, 1Dante S.Lauretta, 2Bjoern Klaue, 3Yulia S.Goreva, 4Joel D.Blum, 5Alexandre Andronikov, 6,7Jordan K.Steckloff
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2018.12.022]
1Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, United States
2TSI GMBH, Neuköllner Strasse 4, Aachen, 52068, Germany
3NASA Jet Propulsion Laboratory, Pasadena, CA, 91109, United States
4Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, United States
5Czech Geological Survey, Geologicka 6, Prague, 152 00, Czech Republic
6Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX, 78712, United States
7Planetary Science Institute, Tucson, AZ, 85719, United States
Copyright Elsevier

Carbonaceous chondrite meteorites are some of the oldest Solar System planetary materials available for study. The CI group has bulk abundances of elements similar to those of the solar photosphere. Of particular interest in carbonaceous chondrite compositions are labile elements, which vaporize and mobilize efficiently during post-accretionary parent-body heating events. Thus, they can record low-temperature alteration events throughout asteroid evolution. However, the precise nature of labile-element mobilization in planetary materials is unknown. Here we characterize the thermally induced movements of the labile elements S, As, Se, Te, Cd, Sb, and Hg in carbonaceous chondrites by conducting experimental simulations of volatile-element mobilization during thermal metamorphism. This process results in appreciable loss of some elements at temperatures as low as 500 K. This work builds on previous laboratory heating experiments on primitive meteorites and shows the sensitivity of chondrite compositions to excursions in temperature. Elements such as S and Hg have the most active response to temperature across different meteorite groups. Labile element mobilization in primitive meteorites is essential for quantifying elemental fractionation that occurred on asteroids early in Solar System history. This work is relevant to maintaining a pristine sample from asteroid (101955) Bennu from the OSIRIS-REx mission and constraining the past orbital history of Bennu. Additionally, we discuss thermal effects on surface processes of near-Earth asteroids, including the thermal history of “rock comets” such as (3200) Phaethon. This work is also critical for constraining the concentrations of contaminants in vaporized water extracted from asteroid regolith as part of future in situ resource utilization for sustained robotic and human space exploration.

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