20-EPN-FT1-024: Untangling rock-inhabiting microorganisms and their biosignatures from the Mars-like area of Puna Plateau, Argentinian Andes
Visit by Lorenzo Aureli and Gerardo Antonio Stoppiello, University of Tuscia (Italy), to TA1.6 Argentinian Andes (Argentina).
Dates of visit: 17-23 April 2022
Report Summary: The hostile current conditions on the surface of Mars entail that, if any form of life exists or ever existed on the planet, it may have adopted survival strategies like those evolved by terrestrial microorganisms inhabiting extremely harsh regions. Here, one of the most common strategies observed is endolithic growth, defined as the colonisation of the small interstices and cracks inside rocks where microorganisms can be protected from external hostile conditions. On the other hand, environments exhibiting a strong negative hydrological balance can be characterised by the sporadic presence of pools saturated in minerals. Here, microorganisms can induce carbonate precipitation along with the physicochemical factors occurring in these environments, causing the formation of sedimentary structures in which they can be trapped.
From an astrobiological perspective, several studies showed how the early Mars environment may have exhibited an overall desertic environment hosting localised water basins. Therefore, the possibility that microbial forms of life may have existed on Mars makes hypothetical endolithic habitats and evaporite deposits on the planet interesting targets for the search for tracks of past life. In this optic, the southern end of the Puna Plateau in the Argentinian Andes (Catamarca province, Argentina) may represent an excellent model to understand how putative microorganisms may be adapted to the early Martian environments and how to detect their signatures. For this reason, a sampling campaign was performed at the Laguna Negra Lake (Puna Plateau region) in April 2022, with the purpose to characterise different microbial habitats hosted in the site.
Read the full scientific report, with kind permission by Lorenzo Aureli.
21-EPN-FT1-003: Biogeochemical tools to search for biosignatures in microbial carbonates from extreme environments
Visit by Sylvie Bruggmann, University of Lausanne (Switzerland) and Camila Areias, Vrije Universiteit Amsterdam (Netherlands), to TA1.6 Argentinian Andes (Argentina).
Dates of visit: 10-16 December 2022
Report Summary: Microorganisms evolved under extreme conditions as the first forms of life on Earth. In the geological record, signatures of these microbial communities can be preserved in the chemistry of sedimentary rocks as microbialites. The identification of their biogenicity, however, is often ambiguous, as biosignatures can be overprinted, and abiotic processes may form similar signatures. Microbialites forming under extreme conditions on the modern Earth can be used as analogues to better understand the formation of biosignatures, and to improve their identification in sedimentary rocks from Earth and Mars.
The TA1 Facility 6 in the Argentinian Andes provides an ideal environment where carbonaceous microbialites form under extreme conditions, such as cold temperatures, low precipitation and high UV radiation. To better resolve the ambiguity of biosignatures, we use a combined approach of organic and inorganic biogeochemical tools to examine sediment and water samples. The organic tool focuses on lipid biomarkers that can be attributed to specific biogenic sources, such as cyanobacteria. In addition, the inorganic tool utilises elemental concentration and isotope compositions of biologically relevant metals, such as Fe or Sr, which can record information of a biogenic or abiotic origin. The combination of these organic and inorganic tools can improve the identification of biosignatures and their credibility can be enhanced.
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.
21-EPN-FT1-026: Biogeochemical cycling in the lake systems of the Argentinian Puna: An investigation into the microbial communities of an exceptional Hesperian martian analogue
Visit by Ben Tatton, The Open University (UK) to TA1.6 Argentinian Andes (Argentina).
Dates of visit: 17-26 April 2022
Report Summary: Fieldwork undertaken as part of the Europlanet fast track funding call took place between 16/04/22 and 26/04/22 as part of an international team of scientists from The Open University, The Università degli Studi della Tuscia, and The Universidad Nacional de Córdoba.
Fieldwork was conducted at two high-altitude Andean Lake (HAAL) sites, Laguna Negra, and Laguna de Antofagasta. The focus of the research was to collect sediment cores and water samples from Laguna de Antofagasta to assess how microbial communities change as a factor of depth within the sediment. During the trip, a total of 5 x 30 cm cores, 5 x 250 ml of lake water for culturing, and 15 x lake water samples for geochemical analysis were collected. Furthermore, environmental variables were taken with pH, temperature, conductivity, redox potential, and UV monitored. The trip was a resounding success with enough samples taken to permit the progression of my PhD. The data gained from the trip will contribute to two or three data chapters. These chapters will focus on the geochemical characterisation of the site, the microbiology of the site, and potentially simulation experiments which will focus on Noachian/Hesperian Mars relevant metabolisms. We expect to find that LDA is a suitable geochemical analogue for Gale Crater during the Noachian Hesperian transition. We also expect that the types of metabolisms found within the sediments are similar to those predicted to have been present on Noachian/Hesperian Mars.