Exobiology and Evolutionary Biology

PI: Linda Jahnke

The objective of this proposal is to study the microbial diversity and the organic composition of phototrophic communities within a mineralogical context of various depositional environments in silica-rich hydrothermal systems of Yellowstone National Park. Similar communities have been shown to contain suites of organic biomarkers whose degradation-alteration products are entrained within the sedimentary record of early Earth. However, little information is available on processes leading to potential preservation of organic matter in silica-rich systems, and/or for potential preservation of secondary trophic biosignatures.
Ample evidence now exists for an early wet Mars during the Noachian period. Hydrothermal systems are likely target environments for the detection of early martian life. Sinter-depositing thermal springs in volcanic terrains have high potential for detection of biosignatures on Mars, and have recently been identified by the MER Spirit rover. The diverse rock types of the Columbia Hills is consistent with volcanism and extensive post-depositional aqueous acid alteration. This Earth-based study of both acid and alkaline hydrothermal microbial systems responds directly and quickly to Mars exploration by identifying potential biosignatures to be sought in future missions.
We propose to identify appropriate sites over a thermal gradient of a slightly alkaline siliceous sinter hot spring to characterize the potential for infilling and cementation on preservation of microbial lipid biomarkers in the palisade and sheet sinter fabrics of the Lower Geyser Basin. We will extend our findings to acid depositional environments within the vapor-dominated, acid-sulfate systems of Norris Geyser Basin by examining organic preservation in various pH sinter-depositing and clay-like lake sediments. We will extend these studies by correlation to more mature sinters using pyropyrolysis GCMS similar to that planned for MSL organic analysis. Providing a library of potential organic signatures within these sinter environments.