This study focuses on living and fossil freshwater microbialites and their potential as proxy for paleoenvironemental reconstructions. Research field is located in the closed continental Maquinchao Basin, in Patagonia (Argentina). Three different stages of microbialite development, namely fossil, recently mineralized and living, are present in different areas of the basin. Compelling evidence including mineralized sheath associated with micritic clots, and laminations of microspar/spar and micrite indicating a mixed biologically-induced and -influenced component in Maquinchao microbialites formation. Similarities in the microstructures and their distribution between the fossil buildups, the recently lithified crusts and the living microbial mats provide critical data filling the gap between living mats and their fossil counterparts. These results allowed us to propose a realistic model of microbialite formation and preservation. It is, hence, providing novel data to better understand the formation, accretion and preservation of the microbialites as well as the paleoenvironmental record of the Maquinchao Basin.