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Abstract EANA2026-31


Preliminary Insights into Microbial Fabrics and Biosignature Preservation in the Mari Ermi Stromatolites (Sardinia, Italy): Implications for Evaporitic Planetary Analogues

Tarozzi A. (1), Pillola G.L.(2), Paladini M. (1), Cavalazzi B. (1,3)
(1) Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna, Italy (2) Department of Chemical and Geological Sciences, University of Cagliari, Cagliari, Italy (3) Department of Geology, University of Johannesburg, Johannesburg, South Africa


Modern stromatolites forming in the Mari Ermi coastal ponds (western Sardinia, Italy) (Saint Martin & Saint Martin, 2015) were investigated as analogues for microbial carbonate precipitation and biosignature preservation under fluctuating evaporitic conditions. The shallow-water system is characterized by strong seasonal evaporation, variable salinity, and active carbonate accretion associated with microbial communities. 

Preliminary petrographic and spectroscopic analyses were conducted on hand specimens and thin sections using transmitted optical microscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), and Raman spectroscopy to characterize stromatolitic fabrics, mineral phases, and microbe–mineral relationships. 

The stromatolites display finely laminated carbonate fabrics preserving abundant filamentous microbial textures embedded within micritic laminae and preferentially associated with more strongly cemented zones. Optical microscopy and SEM observations suggest a close spatial relationship between microbial structures and carbonate precipitation, supporting a biologically influenced contribution to stromatolite accretion. Raman analyses further contribute to identifying mineralogical phases and assessing the preservation potential of organic-related signatures within the laminated framework. 

These preliminary results highlight the potential of the Mari Ermi stromatolites as terrestrial analogues for biosignature formation and preservation in saline and episodically evaporitic environments of astrobiological interest. Ongoing microbiological investigations will further constrain the role of microbial communities in stromatolite development and biosignature preservation, contributing to the interpretation of organo-mineral associations in ancient terrestrial and potentially extraterrestrial settings. 

This study is part of the Space It Up project funded by the Italian Space Agency (ASI) and the Ministry of University and Research (MUR) under contract no. 2024-5-E.0 – CUP I53D24000060005.