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Microbially-Induced Sedimentary Structures Microbialite: a rock formed via the influence of microbial trapping, binding, and precipitation Microbial assemblages (in biofilms) form sticky films that influence sediment deposition Microbially-bound sediments are stabilized and more cohesive Trapping, binding by bacteria Aragonite precipitation beneath biofilm Sediment Influx Micritization welds grains together Early cementation critical for growth of microbialites Stromatolite: laminated organosedimentary structure created by trapping and binding of sediment by a microbial biofilm Thrombolite: clotted, non-laminated microbialite Require lower sediment influx, form in subtidal environments Microbialites in siliciclastics (e.g., “wrinkle structures”) do not form structures with relief above seafloor, likely due to lack of carbonate precipitation Wrinkle Structures, Lower Cambrian
