The research was focused on micro-nanomorphology and biogeochemistry of the very fine dark and white wrinkled laminated microbialites to investigate the traces of prokaryotic metabolic activity, which possibly induced their precipitation. Epifluorescence observations put in evidence a high organic matter content mainly in the dark laminae. The geochemical characterization of extracted organic matter was performed through the functional group analyses by FT-IR Spectroscopy. FT-IR parameters indicate a marine origin and low thermal evolution for these organic compounds. The organic matter, which is characterized by the presence of stretching ¦ÍCC vibrations attributable to alkene and/or unsaturated carboxylic acids, is likely to have been synthesized by bacteria and/or archaea communities.