Astrobiological implications of microbial morphologies in cold fluid-generated carbonates Original Research Article

Carbonate deposits are usually related to biological activity and their identification as targets for astrobiological research concerns their being potentially present on other planetary surfaces, including Mars. On Earth, chemosynthetic-generated (non-hydrothermal) carbonates are biologically precipitated deposits produced by outgassing not linked to volcanic activity. Similarly to the Earth, cold outgassing sites could be present in other planetary bodies of the Solar System. In cold fluid-generated carbonate bodies from Morocco and Italy, belonging to different geological ages and environmental settings, we describe complex structures that we have attributed to microbial activity. Even when morphological evidences of cells or colonies of microorganisms are absent, the biogenicity of these structures is based on a variety of evidences including morphologic comparisons with present-day analogues, type of mineral replacement, and geological context. Our finding of unambiguous, microbial-derived structures in cold fluid-generated carbonates improves the astrobiological potential of these types of rocks.