Table 1. Representative reactions.
Carbonate reactions |
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Calcite/aragonite dissolution/precipitation: |
H2O + CO2 + CaCO3 = Ca2+ + 2HCO3- |
Dolomite dissolution/precipitation: |
2H2O + 2CO2 + CaMg(CO3)2 = Ca2+ + Mg2+ + 4HCO3- |
Organic remineralization (redox pathways) |
Suboxic diagenesis: |
Mn and Fe reduction dissolved Mn2+ and Fe2+ increase |
Sulfate reduction: |
(CH2O)106(NH3)16(H3PO4) + 53SO42- 106HCO3- + 53HS- + 16NH3 + H3PO4 + 53H+ |
Silicate reactions |
Low-temperature decomposition (dissolution/hydrolysis) of basaltic basement: |
basaltic glass, plagioclase, and olivine e.g., release of Ca2+ , Mg2+ , Fe2+ , HCO3-, and H4SiO4 (liberated Mg2+, H4SiO4, and Fe2+ rapidly removed via smectite precipitation) |
K-feldspar kaolinite: |
2KAlSi3O8 + 2H+ + 9H2O Al2Si2O5(OH)4 + 2K+ + 4H4SiO4 |
Kaolinite illite: |
5Al2Si2O5(OH)4 + 2K+ + 2HCO3- + 4SiO2(aq) 2KAl5Si7O20(OH)4 + 7H2O + 2CO2 |
Kaolinite Mg-smectite: |
7Al2Si2O5(OH)4 + 8SiO2(aq) + Mg2+ 6[(Al2.00)(Si3.67Al0.33)O10(OH)2]Mg0.167 + 7H2O + 2H+ |
Albite Na-smectite: |
2.33NaAlSi3O8 + 8.64H2O + 2CO2 Na0.33Al2.33Si3.67O10(OH)2 + 2Na+ + 2HCO3- + 3.32H4SiO4 |