9.3 Microbial Processes in Carbonate Formation

Microbes play a crucial role in carbonate formation through various processes. They create nucleation sites, alter local chemistry, and drive metabolic reactions that lead to mineral precipitation. Understanding these mechanisms is key to grasping how microorganisms shape our planet's geology.

Environmental factors like temperature, pH, and salinity influence microbial carbonate formation. These processes result in distinct sedimentary structures such as stromatolites and microbialites, which serve as important indicators of past and present geological conditions.

Microbial Processes in Carbonate Formation

Microbial processes in carbonate formation

Top images from around the web for Microbial processes in carbonate formation

• 

  Frontiers | We Are One: Multispecies Metabolism of a Biofilm Consortium and Their Treatment ... View original

  Is this image relevant?

• 

  Frontiers | Carbonate Precipitation through Microbial Activities in Natural Environment, and ... View original

  Is this image relevant?

• 

  Frontiers | Beyond Risk: Bacterial Biofilms and Their Regulating Approaches View original

  Is this image relevant?

• 

  Frontiers | We Are One: Multispecies Metabolism of a Biofilm Consortium and Their Treatment ... View original

  Is this image relevant?

• 

  Frontiers | Carbonate Precipitation through Microbial Activities in Natural Environment, and ... View original

  Is this image relevant?

1 of 3

Top images from around the web for Microbial processes in carbonate formation

• 

  Frontiers | We Are One: Multispecies Metabolism of a Biofilm Consortium and Their Treatment ... View original

  Is this image relevant?

• 

  Frontiers | Carbonate Precipitation through Microbial Activities in Natural Environment, and ... View original

  Is this image relevant?

• 

  Frontiers | Beyond Risk: Bacterial Biofilms and Their Regulating Approaches View original

  Is this image relevant?

• 

  Frontiers | We Are One: Multispecies Metabolism of a Biofilm Consortium and Their Treatment ... View original

  Is this image relevant?

• 

  Frontiers | Carbonate Precipitation through Microbial Activities in Natural Environment, and ... View original

  Is this image relevant?

1 of 3

• Microbial-induced carbonate precipitation (MICP) occurs through extracellular polymeric substances (EPS) production creating nucleation sites for mineral formation
• Metabolic processes drive carbonate formation:
  1. Photosynthesis uptakes CO2 increasing pH
  2. Ureolysis hydrolyzes urea producing carbonate ions
  3. Ammonification degrades organic nitrogen compounds
• Biofilm formation traps and binds sediments facilitating carbonate precipitation
• Sulfate reduction produces bicarbonate ions contributing to carbonate formation

Microbial metabolism and carbonate minerals

• Precipitation mechanisms involve altering local chemical environment by increasing pH and supersaturating carbonate ions
• Dissolution processes occur through acid production during organic matter oxidation and CO2 release during respiration
• Metabolic pathways influencing carbonate dynamics:
  • Autotrophic pathways fix carbon leading to alkalinization
  • Heterotrophic pathways produce organic acids potentially causing dissolution
• Enzymatic activities like carbonic anhydrase catalyze CO2 hydration affecting carbonate equilibrium

Environmental factors of microbial carbonates

• Temperature affects microbial growth rates and impacts carbonate solubility (warmer temperatures generally increase precipitation)
• pH variations influence carbonate formation (alkaline conditions favor precipitation, acidic conditions promote dissolution)
• Salinity impacts ion availability for carbonate formation and creates osmotic stress on microbial communities
• Light availability drives photosynthetic activity in photic zones (coral reefs, shallow marine environments)
• Nutrient concentrations, especially calcium and magnesium availability, affect carbonate precipitation rates
• Hydrodynamic conditions influence microbial colonization and sediment transport (calm waters vs high-energy environments)

Microbial carbonates in sedimentary structures

• Stromatolites form layered microbial mats creating accretionary structures (Shark Bay, Australia)
• Microbialites develop as organosedimentary deposits with microbial origins (Lake Clifton, Western Australia)
• Thrombolites appear as clotted microbial structures (Lake Thetis, Western Australia)
• Carbonate mud production influenced by microbial activity forms fine-grained sediments
• Bioherm and biostrome development contribute to reef-like structures (Great Barrier Reef)
• Diagenetic processes involve microbial activity in early lithification, cementation, and porosity alterations
• Paleoenvironmental indicators use microbial carbonates as proxies for ancient environments (Precambrian stromatolites)