MICROBIALLY INDUCED SEDIMENTARY STRUCTURES – A NEW WINDOW FOR THE UNDERSTANDING OF LIFE AND LIFE CONDITIONS IN THE PRECAMBRIAN

Microbially induced sedimentary structures (MISS) form the 5th group in the classification of primary sedimentary structures. They occur not only in modern coastal and shelf deposits, but are known since the Early Archean. Whereas their counterparts, the familiar stromatolites, are characteristic for carbonate environments, MISS are typical phenomena of siliciclastic and evaporitic milieus.

Both actualistic investigations in the modern environments, and comparative studies in fossil deposits showed that MISS record the interaction of benthic microbial populations with the environmental conditions. The main categories of MISS are: (i) structures induced by leveling; (ii) structures induced by biostabilization; (iii) structures induced by imprinting; (iv) structures induced by microbial grain separation; and (v) structures induced by baffling, trapping and binding.

Due to their complex modes of formations, MISS record the physiological abilities of benthic bacteria and permit conclusions on the evolution of microorganisms. In addition, the structures mirror the ancient hydrodynamic and climatic parameters. Therefore, the group of MISS constitute a new and important tool in the investigation of the strange Precambrian worlds.