Precambrian banded iron formations are hydrothermal chemical sediments composed of Fe-rich minerals with alternating chert layers. Because of their possible precipitation microorganisms may provide a small comparison to the conditions under which they are built-in by studying bacterial-mineral interactions in the current hydro-thermographic environments. Interestingly, the recent heat growth of microbial populations deep-sea springs and shafts are typically trapped in minerals of iron or silicate. The interaction between the reactive cell sites of a cationic iron from the hydrothermal is the passive way of iron biomineralization. Bacteria, such as Gallionella, fluid, or active chemolithotrophic-oxidation. The hydrogen-bonded between hydroxyl groups in extracellular polymers and hydroxyl groups precipitates amorphous silica into individual bacteria in dissolved silica, with certain colonies being completely cemented into one silica matrix up to several micrometers in thickness. Iron silicates form as a result of reactions from silica to cellular iron. Bacterial cells simply catalyzed reactions in these mainly non-specific systems, which are possible by supersaturated conditions resulting in sudden physical and chemical changes caused by vents. The diagnosis of these primary precipitates can also be changed by the diagnostic response, some of which are also catalyzed by microorganism sediment-growing, leading to the formation of secondary magnetite and siderite. This can be achieved in combination with all the major mineralogical components of BIFs.

1. Hydrothermal Bacterial Bio Mineralization:
Potential Modern-Day analogues for Banded Iron –
Formations
Aamir Ali（阿米若）
Master Student
同济大学

2. Contents
 Biomineralization
 Hydrothermal vents microbial Communities
 Hydrothermal Bacterial Bio mineralization
 Banded iron formation(BIFs), Classification & Origin.
 Biogenically BIFs Formation
 Hydrothermal Biominerals(Iron hydroxides,
Amorphous silica, Iron –Silicates)
 Difference and Similarites of BIFS

3. Bio mineralization
Fig.3 variety of mollusc shells (gastropods,
snails and seashells)..(Wikipedia)
Fig 2. Cupravidus metallidurans. wikipedia
Fig.4 Coccolithophores
Fig 1. Biomineralizations observation by Nasa(Wikipedia)

4. Hydrothermal vent microbial communities
Fig1: Chemosynthetic microbial mats at the
junction between hydrothermal vent and coral
reef communities.
Fig 2: Hydrothermal vent
Fig.3 Yellow stone national park, Geysers

5. Hydrothermal Bacterial Bio mineralization
 Bacteria contribute significantly to the development of
extremely fine-grained.
 Iron oxyhydroxides
 Carbonates
Fig 2. The phototrophic Fe(II)- oxidizing
Rhodobacter ferrooxidans attached to ferric
hydroxide (from Konhauser et al., 2005).
Fig 1.CaCO3 -impregnated cyanobacterial sheath
Tarim, China. Width of view 1 mm.

6. Precambrian Banded Iron Formation
• Sedimentary rock consisting of alternating layers of iron
oxides and iron-poor chert.
Fig 1. BIFS Karijini National Park, Western Australia
Frank Gregory

7. Classification of BIFs according to
facies: (Mineralogy of BIFs)
• Oxides facies
• Silicate facies
• Carbonate facies
• Sulphide facies
Fig.1 Mineralogical classification of BIFS

8. Classification of BIFs according to geologic
setting
• Algoma type
• Superior type
Fig 1: 3-billion-year-old banded iron formation from
Canada, (internet website)
(Wikipedia)

9. Origin of BIF
• Sedimentary
• Volcanic
• Biogenic
Volcanic origin Biogenic origin

10. Fig 1. Overview of the laminated BIF from the Joffre iron formation, Pilbara Craton, north-west Australia.

11. Biogenically Origin of Precambrian BIF
• Hydrothermal origin and consist of Fe-rich minerals with
alternating layers of chert.
• Bacterial-mineral interactions at modern hydrothermal
environments may provide small-scale analogues.
• Deep sea vents and Hot springs
• Chemo lithotrophic
• Iron biomineralization(Gallionella genera)
• Amorphous Silica (Chloroflexus aurantiacus)
• Iron-silicate biomineralization
• Diagenetic reactions(BIFs: Siderite & Magnetite)

12. HYDROTHERMAL BIOMINERALIZATION
Synechococcus, wikipedia Chloroflexus. Sp, wikipedia
Gallionella ferruginea,wikipedia
 Inhabiting environments(hydrothermal vents and hot springs)
 Mats growing
 Actively promote mineral formation

13. Fig 1: SEM image of sever Gallionella ferruginea stalks
making up a network within a biofilm. From Halbach,
Koschinsky, and Halbach.
Fig 2: SEM image of a twisted stalk of Gallionella ferruginea.
From Halbach, Koschinsky, and Halbach.

14. iron Hydroxides
Fig. 3: Electron micrograph of Vestimentiferan
tube from juan de fuca ridge. SEM,
Colonization sheathed bacteria.(Juniper and
Tebo,1995)
Fig.1: TEM Epilithic bacterial cell from a hot spring effluent
channel at Iceland. Scale: 140nm, Gallionella ferruginea.
(Juniper and Tebo,1995)
 Hydrated polysaccharide material.
 Marine Hydrothermal environment
 Bacterial filaments growing in mud deposit
Fig.2 Vestimentiferan tubes, Riftia Pachyptilla(Wikipedia)

15. Fig 1: B. TEM. Fe particles, Accumulation sheath of bacterium.
C. Extensive Fe particle accumulation and Extracellular slime. juniper & Tebo,1995)

16. Amorphous Silica
Fig 2: TEM image of a colony Filamentous bacteria (from
Geysir, Iceland). Scale bar= 1.1um.
Fig 1: SEM image showing Filamentous micro-texture of
Hydrothermal deposit( Juniper and Fouquet. 1988)
Fig 3: SEM Image Filament heavily coated in silica
(Juniper and Fouquet. 1988).
 Catalyze silica precipitation(Microbial mats)
 Chloroflexus aurantiacus
 Synechococcus,sp
 Filamentous Microtexture

17. Iron -Silicates biomineralization
Fig 1: TEM image of a Bacterial cell from
Krisuvik, Iceland, with amorphous iron-silicate
grains. Scale bar: 200nm
 Granular and Spheroidal crystallites
 Microbial-mineral flocs
 Metal participated in a cationic bridging mechanism
Fig 2: TLM image of the filament-
mineral association in iron-silica
deposits in a chimney fragment, East
Pacific Rise. (juniper and Fouquet)

18. Similarities between persent day-percamberian
hydrothermal biomineralization: BIFs
• High elemental concentrations in marine Environment
(1000ppm- & 50,000ppm) and Hot Springs(200ppm-
1100ppm).
• Consortium microorganism(3.5B)
• Primary mineralized constituents of BIF(iron, silica)
• Crenothrix sp, Sphaerotilus, Leptohrix.
Bended Iron FormationsStromatolites

19. Difference between persent day-percamberian
hydrothermal biomineralization: BIFs
• The size of the deposits(Oxygenated conditions).
• The relationship between the microorganisms and the
chemocline.
Fig 1: Schematic Diagram of the Archean environment, modified from Lowe (1994).

20. Fig 1: Schematic diagram of BIF; deposition in the Proterozoic, modified from a
genetic model of the Hamersley Group (-2.5 Ga) from Morris (1993).

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