Transcript microbial

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