21-EPN-FT1-020: Preservational Potential of Microbialite Biosignatures in Basalt-Hosted Lacustrine Environments – Perspectives for Martian Biogeochemistry and Mars Sample Return

Visit by Keyron Hickman-Lewis of the Natural History Museum, London (UK) to TA1.6 Argentinian Andes (Argentina).
Dates of visit: 04-10 April 2023

Report Summary: With Europlanet support, we visited two field sites in Argentinian Patagonia in which well-preserved palaeolacustrine stromatolitic carbonates occur. The stromatolites examined range from several tens of thousands to several million years in age and occur in palaeolake settings that bear resemblance to similar environments identified on the Noachian–Hesperian Mars. We performed field investigations of the occurrence and macrostructure of these stromatolites and collected samples to enable a multidisciplinary study of the microbial biosignatures preserved within.

We identified morphologically diverse stromatolites including domical, columnar and crust-precipitating forms, from which we will seek evidence for diversity in microstructural complexity, organic compositions, and inorganic geochemistry. The regional and local setting of these stromatolites, coupled with their microbially dominated compositions, means that these materials provide exceptional field analogues and potential ecosystem analogues for similar sequences on the ancient Mars, and may provide guidance for biosignature exploration strategies and life detection in geological materials at the Martian surface during ongoing and future rover missions. Upon return to our home institutions, these materials were studied using a range of bulk and in situ microscopy and spectroscopy techniques to evaluate the nature and distribution of microbial biosignatures preserved within.

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