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Reading list:

Weathering. Reading list: Brantley, S., and 26 others, 2011, 12 testable hypotheses on the geobiology of weathering, Geobiology, 9, 140-165. Hamblin, W.K. and Dr. Eric H. Christiansen, E.H., 2004, Chapter 10 - Weathering, Earth's Dynamic Systems, Tenth Edition, Prentice Hall.

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Reading list:

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  1. Weathering Reading list: Brantley, S., and 26 others, 2011, 12 testable hypotheses on the geobiology of weathering, Geobiology, 9, 140-165. Hamblin, W.K. and Dr. Eric H. Christiansen, E.H., 2004, Chapter 10 - Weathering, Earth's Dynamic Systems, Tenth Edition, Prentice Hall. Kump, L., Brantley, S., and Arthur, M., 2000, Chemical weathering, atmospheric CO2 and climate, Annual Reviews of Earth and Planetary Science, v. 28, pp. 611-667. Liu, Z., Dreybrodt, W., and Liu, H., 2011, Atmospheric CO2 sink: silicate weathering or carbonate weathering? Applied Geochemistry, v. 26, pp. S292-S294. Riebe, C., Kirchner, J.W., and Finkel, R.C., 2004, Erosional and climatic effects on long-term chemical weathering rates in granitic landscapes spanning diverse climate regimes, Earth and Planetary Science Letters, v. 224, pp. 547-562. L. Hinnov February 17, 2012

  2. PHYSICAL CHEMICAL feedbacks Physical weathering is the mechanical fragmentation of rocks from stress acting on them from Earth surface processes. Chemical weathering involves chemical reactions between Earth surface chemistry (water) and minerals that progressively decompose solid rock. Famous experiment: Griggs, 1936 heated and cooled cubes of granite 140ºC to 30ºC for the equivalent of 240 years of daily fluctuations, but nothing happened. That was dry, but with wetting, in ~2.5 years they fell apart. Major products of weathering: (1) fractured rock (2) regolith (3) ions in solution

  3. Brantley et al. (2011) Hamblin & Christiansen (2004)

  4. CONDITIONS ASSOCIATED WITH CHEMICAL V. PHYSICAL WEATHERING

  5. COMMON MINERALS IN ROCKS Common rock-forming minerals Crustal abundance of minerals Ronov & Yaroshevsky, 1969

  6. COMMON MINERALS IN ROCKS The higher the Si:O ratio, the more resistant a mineral is to chemical weathering:

  7. Goldich Stability Series “Reverse Bowen Reaction Series” High temp. minerals weather first….

  8. CHEMICAL WEATHERING OF ROCKS AND CO2 DRAWDOWN: 1) Congruent-minerals totally dissolve 2) Incongruent-mineral is transformed into another mineral COMMON WEATHERING REACTIONS: carbonation (breakdown by weakly acidic rainwater) hydrolysis (breakdown by water) hydration (breakdown by the absorption of water) oxidation (breakdown by the oxygen in air and water) CARBONATION (DISSOLUTION): Calcite: HYDROLYSIS: Plagioclase (albite): Crustal abundance of minerals Potassium Feldspar: 2KAlSi3O8 + 9H2O + 2CO2 ⇌ Al2Si2O5(OH)4 (kaolinite) + 2HCO3- + 4H4SiO4 + 2K+ 3KAlSi3O8 + 14H2O + 2CO2 ⇌ KAl3Si3O10(OH)2(illite) + 2HCO3- + 6H4SiO4 + 2K+ Depending on K+ content of the solution.

  9. Olivine: Wollastonite: (a pyroxene) CHEMICAL WEATHERING OF ROCKS AND CO2 DRAWDOWN:

  10. DISSOLUTION RATE OF PLAGIOCLASE Brantley et al. (2011) Laboratory rates are order of magnitude faster than natural rates Note: BET analysis = Brunauer-Emmett-Teller (BET) Surface Area Analysis

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