Mineralogical analyses of surface sediments in the Antarctic Dry Valleys: coordinated analyses of Raman spectra, reflectance spectra and elemental abundances

Janice L Bishop; Peter A J Englert; Shital Patel; Daniela Tirsch; Alex J Roy; Christian Koeberl; Ute Böttger; Franziska Hanke; Ralf Jaumann

doi:10.1098/rsta.2014.0198

Mineralogical analyses of surface sediments in the Antarctic Dry Valleys: coordinated analyses of Raman spectra, reflectance spectra and elemental abundances

Philos Trans A Math Phys Eng Sci. 2014 Dec 13;372(2030):20140198. doi: 10.1098/rsta.2014.0198.

Authors

Janice L Bishop¹, Peter A J Englert², Shital Patel³, Daniela Tirsch⁴, Alex J Roy⁵, Christian Koeberl⁶, Ute Böttger⁴, Franziska Hanke⁷, Ralf Jaumann⁴

Affiliations

¹ Carl Sagan Center, SETI Institute, 189 Bernardo Avenue, Mountain View, CA, USA NASA Ames Research Center, Moffett Field, CA, USA jbishop@seti.org.
² Hawaii Institute of Geophysics and Planetology, University of Hawaii at Mânoa, HI, USA.
³ Carl Sagan Center, SETI Institute, 189 Bernardo Avenue, Mountain View, CA, USA Department of Chemistry, San Jose State University, San Jose, CA, USA.
⁴ German Aerospace Center (DLR), Berlin, Germany.
⁵ Department of Land and Natural Resources, Honolulu, HI, USA.
⁶ Department of Lithospheric Research, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria Natural History Museum, Burgring 7, 1010 Vienna, Austria.
⁷ German Aerospace Center (DLR), Berlin, Germany Technische Universität Berlin, Berlin, Germany.

PMID: 25368345
DOI: 10.1098/rsta.2014.0198

Abstract

Surface sediments at Lakes Fryxell, Vanda and Brownworth in the Antarctic Dry Valleys (ADV) were investigated as analogues for the cold, dry environment on Mars. Sediments were sampled from regions surrounding the lakes and from the ice cover on top of the lakes. The ADV sediments were studied using Raman spectra of individual grains and reflectance spectra of bulk particulate samples and compared with previous analyses of subsurface and lakebottom sediments. Elemental abundances were coordinated with the spectral data in order to assess trends in sediment alteration. The surface sediments in this study were compared with lakebottom sediments (Bishop JL et al. 2003 Int. J. Astrobiol. 2, 273-287 (doi:10.1017/S1473550403001654)) and samples from soil pits (Englert P et al. 2013 In European Planetary Science Congress, abstract no. 96; Englert P et al. 2014 In 45th Lunar and Planetary Science Conf., abstract no. 1707). Feldspar, quartz and pyroxene are common minerals found in all the sediments. Minor abundances of carbonate, chlorite, actinolite and allophane are also found in the surface sediments, and are similar to minerals found in greater abundance in the lakebottom sediments. Surface sediment formation is dominated by physical processes; a few centimetres below the surface chemical alteration sets in, whereas lakebottom sediments experience biomineralization. Characterizing the mineralogical variations in these samples provides insights into the alteration processes occurring in the ADV and supports understanding alteration in the cold and dry environment on Mars.

Keywords: Antarctic Dry Valleys; Raman spectra; chemistry; reflectance spectra; sediments.