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Iron and Manganese - Coggle Diagram

- - - - fe2+ soluble in acidic rain
        
        dissolved fe2+ carried by groundwater
        
        oxidised to form fe3+ which is precipitated
  - - - physical erosion by overflow water
    - - chemical weathering
      - water infiltrates, percolates and oxidises
- - - - old cratonic rocks
    - - Associated with limestones
- - - - Archaean no oxygen due to no photosynthesis
    - - creates redoxcline
    - - Fe3+ precipitates as iron oxide
    - - winter less photosynthesis, less o2, no oxidation, no precipitation
      - more silica rich in winter
  - - - iron oxyhydroxides precipitated on seafloor
      - anoxygenic
      - oxidises iron at iron chemocline
- - - - powder by crushing and grinding
      - hydrophobic solution bubbled through the material
      - waste products stick to surface bubbles
    - - still lots of mixing, good for iron
- - - - iron precipitated
    - - BIFs stop being formed
- - - - Fe silicates and carbonates gel
      - silica gel
        
        no modern silica gel precipitation
        
        silica level in ocean too low for saturation
        
        animals remove silica from seawater to make shells
        
        occurred before organisms existed
      - gels to BIFS through diagenesis and lithification
- - - - upwelling of iron mixes from the deep
      - oxygen-rich
      - iron reacts in water column and precipitates at surface
    - - only Phanerozoic