21-EPN-FT1-018: Biogeochemistry in extreme environments: assessing analogues to early Earth environmental conditions in high-altitude hypersaline Andean lakes
Visit by Alexandra Rodler, Austrian Academy of Sciences (Austria) to TA1.6 Argentinia Andes (Argentina).
Dates of visit: 11-16 December 2022
Microbial activity leaves fingerprints in the sedimentary record, for example, by changes in trace element and isotope ratios. If distinguishable from purely abiotic processes, these traces can potentially be used as biosignatures for geobiological and astrobiological research. Modern analogue environments are useful for better understanding traces of microbial life in the geologic record. This can help to define search criteria for potentially habitable environments on other terrestrial planets. The test site for this project is the Precambrian-analogue TA1 Facility 6 in the Argentinian Andes. This is a shallow lake system with extensive microbial mats, hypersaline conditions at slight acidity, with extreme temperature fluctuations and high-UV ray influx.
Using samples from this site, this project compares between chemically- and microbially influenced carbonate precipitation to further explore if trace element behaviour is related to biological processes, and if specific elements can be used as potential biosignatures. Furthermore, this project investigates trace element behaviour along redox gradients between hydrogenetic and diagenetic microbialite growth. To address if certain elements can serve as biosignatures, we pair petrographic/mineralogical approaches with high-resolution sampling for analysing trace elements as well as redox-sensitive elements and their stable isotopes. The results of this work are integrated in ongoing work focused on the geochemistry of carbonate phases of modern and ancient microbialites as well as the ongoing microbiological work including microbial diversity and metagenomics at this site. This ensures that the results are integrated in and compatible with these diverse fields of research.