1. Microbially-Induced Sedimentary Structures

2. 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

3. Trapping, binding by bacteria Micritization welds grains together
Sediment Influx
Trapping, binding by bacteria
Micritization welds grains together
Decay of heterotrophic bacteria increases alkalinity, favoring precipitation
Early cementation critical for growth of microbialites
Aragonite precipitation beneath biofilm

4. Stromatolite: laminated organosedimentary structure created by trapping and binding of sediment by a microbial biofilm

5. Thrombolite: clotted, non-laminated microbialite
Require lower sediment influx, form in subtidal environments

6. Microbialites in siliciclastics (e. g
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