Reflectance spectroscopy of oxalate minerals and relevance to solar system carbon inventories

1Daniel M. Applin, 1,2,3Matthew R.M. Izawa,1Edward A. Cloutis
1Hyperspectral Optical Sensing for Extraterrestrial Reconnaissance Laboratory, Dept. Geography, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada R3B 2E9
2Dept. Earth Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, Canada L2S 3A1
3Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719-2395

The diversity of oxalate formation mechanisms suggests that significant concentrations of oxalic acid and oxalate minerals could be widely distributed in the solar system. We have carried out a systematic study of the reflectance spectra of oxalate minerals and oxalic acid, covering the 0.2-16 µm wavelength region.. Our analyses show that oxalates exhibit unique spectral features that enable discrimination between oxalate phases and from other commonly occurring compounds, including carbonates, in all regions of the spectrum except for the visible. Using these spectral data, we consider the possible contribution of oxalate minerals to previously observed reflectance spectra of many objects throughout the solar system, including satellites, comets, and asteroids. We find that polycarboxylic acid dimers and their salts may explain the reflectance spectra of many carbonaceous asteroids in the 3 µm spectral region.. We suggest surface concentration of these compounds may be a type of space weathering from the photochemical and oxidative decomposition of the organic polymer found in carbonaceous chondrites. The stability and ubiquity of these minerals on Earth, in extraterrestrial materials, and in association with biological processes make them useful for many applications in Earth and planetary sciences.

Reference
Applin DM, Izawa MRM, Cloutis EA (2016) Reflectance spectroscopy of oxalate minerals and relevance to solar system carbon inventories. Icarus (in Press)
Link to Article [doi:10.1016/j.icarus.2016.05.005]
Copyright Elsevier

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