P059-07
Using Remote Sensing to Characterize Change in Planetary-Analog Brine Environments

Monday, 14 December 2020: 08:48
Virtual
Taylor Plattner1, Britney E Schmidt1, Kynan Hughson1, Alison Olcott2, Peter T Doran3, Jeff Shovlowsky Bowman4 and OAST Team, (1)Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA, United States, (2)University of Kansas, Department of Geology, Lawrence, KS, United States, (3)Louisiana State University, Department of Geology and Geophysics, Baton Rouge, United States, (4)Scripps Institution of Oceanography, Integrative Oceanography Division, La Jolla, CA, United States
Abstract:
The Western Australia Transient Lakes (WATL) are a system of hundreds of chemically complex, ephemeral saline lakes which host complex microbial communities in the Archean Yilgarn Craton. This investigation focuses on these lakes as field analogs for the Oceans Across Space and Time (OAST) project. The Yilgarn craton is approximately the same age as Noachian and Hesperian terrains on Mars, which along with their composition makes this system a uniquely suited analog for Mars to explore the preservation of exotic putative biomarkers, including “Hairy Blobs”.

The varied physicochemical conditions within the WATL present challenges for organisms and influence the boundary between life and non-life. The WATL are excellent targets for investigations on the limits of habitability because they have a wide range of geochemical conditions, including pH (1.7 < pH < 8.6), salinity (10-280 ppt), and temperatures (0-50°C). To characterize and select field sites from the hundreds of shallow lakes, we used spectral data from the Operational Land Imager onboard Landsat 8 and from the Advanced Spaceborne Thermal Emission and Reflection Radiometer onboard the Terra spacecraft to determine whether wet/dry cycles within these lakes could be detected from orbit, and what type of evaporative minerals they contain, mimicking the kinds of analyses used for planetary landing site selection. Seasonal variation in groundwater level and precipitation causes variability in the composition, pH, and salinity of the WATL; understanding how these lakes vary through wet/dry cycles is critical for contextualizing in situ data. A prominent indicator of seasonal change is the abundance of evaporative minerals (such as halite and gypsum) within the lakes and around their shorelines. The Landsat 8 database was used to examine the temporal and compositional evolution of the lakes through the use of spectral classification and mineral indices. Through these analyses we show there is motivation for a second sampling season to analyze and sample a subset of lakes that are located in southern WA for biomarkers and biological activity. We further describe how these data constrain a range of physical and environmental characteristics that make them exciting analogs for stages of aqueous evolution of planetary surfaces.

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