1. Diagenesis Process of turning sediments into sedimentary rocks  water-rock interactions precipitating minerals Water is pores of sediments –‘fresh’ muds can be >80% water… –Water can be trapped at time of deposition, transported in, or evolved from dehydration reactions of hydrous minerals Also can be significant organic matter –Drive redox reactions – reduce Fe 3+, Mn 4+, SO 4 2- …

2. Diagenesis Muds are compacted to shales – water is expelled, though up to 30% H 2 O can remain associated with clays even at 1 km depth Minerals from water and changing conditions  clays, sulfides, siicates, carbonates

3. Clay Geochemistry Clays can have significant chemical substitution, they undergo phase transitions as diagenesis proceeds Illites  Smectites in shales for example Al 2 Si 4 O 10 (OH) 2 *nH 2 O + KAlSi 3 O 8  KAl 2 (AlSi 3 )O 10 (OH 2 ) + 4 SiO 2(aq) + n H 2 O

4. Sandstone Diagenesis Sandy sediments have high permeability, meaning water flows through them faster The water brings ions, precipitation of calcite and silica occurs – WHY? These minerals cement the sediments Silica becomes a more important cementing material at high T Pressurized pockets can become more concentrated, when the pressure is released they are instantly supersaturated…

5. Carbonate Diagenesis Aragonite and Mg-rich calcite are the major phases associated with shallow sedimentary carbonates Dolomite problem: Dolomite is not the first thing to form typically from a water, why are units of calcite so extensively dolomitized? Reaction requires a higher Mg/Ca ratio – occurring perhaps in sabka (supratidal pools) environments, or at seawater-meteoric water interfaces – where calcite is undersaturated but dolomite is supersaturated

6. How do these ions get to these places and form cement? Transport through water… Diffusion and advection account for the movement of ions

7. Soil soil - (i) The unconsolidated mineral or organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants. (ii) The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics.

8. Soil stratigraphy Soil layers, or Horizons, lettered O  A  E  B  C  R O = organic layer = plant fibers, high organics, leafy A = topsoil = minerals + organics E = leached layer = minerals leached, low organics B = accumulation zone = leached and carried down, lots of clays C = Parent material – partially weather original minerals R = bedrock

9. Soil Components Minerals Organic Material Microorganisms Plants Gas – CO 2, CH 4, H 2 S, etc. Water Soil fabric – spatial arrangement of these things Liquid – 1-35% Chelates – organics that bond metals strongly, solubilizing them (bidentate or polydentate = 2 or 2+ bonds to the metal) –Equilibrium description?

10. Chelators These are key organic compounds which SIGNIFICANTLY affect how much metals get into water and how they can be transported: Cu solubility: Cu 2+ + EDTA  Cu(EDTA) log K = 18 2Cu + + O 2- = Cu 2 O log K = -15